Copywriteroffice

Serp data

Request Result

The request result help you to show your API requests results.

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                            [serp_description] =>  The main driver of climate change is the greenhouse effect. Some gases in the Earth's atmosphere act a bit like the glass in a greenhouse, trapping the sun's heat and stopping it from leaking back into space and causing global warming.
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                            [body] => Causes of climate change Humans are increasingly influencing the climate and the earth's temperature by burning fossil fuels, cutting down forests and farming livestock.This adds enormous amounts of greenhouse gases to those naturally occurring in the atmosphere, increasing the greenhouse effect and global warming. Greenhouse gases. The main driver of climate change is the greenhouse effect. Some gases in the Earth's atmosphere act a bit like the glass in a greenhouse, trapping the sun's heat and stopping it from leaking back into space and causing global warming.Many of these greenhouse gases occur naturally, but human activity is increasing the concentrations of some of them in the atmosphere, in particular:carbon dioxide (CO2)methanenitrous oxidefluorinated gasesCO2 produced by human activities is the largest contributor to global warming. By 2020, its concentration in the atmosphere had risen to 48% above its pre-industrial level (before 1750).Other greenhouse gases are emitted by human activity in smaller quantities. Methane is a more powerful greenhouse gas than CO2, but has a shorter atmospheric lifetime. Nitrous oxide, like CO2, is a long-lived greenhouse gas that accumulates in the atmosphere over decades to centuries.Natural causes, such as changes in solar radiation or volcanic activity are estimated to have contributed less than plus or minus 0.1°C to total warming between 1890 and 2010. Causes for rising emissions. Burning coal, oil and gas produces carbon dioxide and nitrous oxide.Cutting down forests (deforestation). Trees help to regulate the climate by absorbing CO2 from the atmosphere. When they are cut down, that beneficial effect is lost and the carbon stored in the trees is released into the atmosphere, adding to the greenhouse effect.Increasing livestock farming. Cows and sheep produce large amounts of methane when they digest their food.Fertilisers containing nitrogen produce nitrous oxide emissions.Fluorinated gases are emitted from equipment and products that use these gases. Such emissions have a very strong warming effect, up to 23 000 times greater than CO2. Global warming. 2011-2020 was the warmest decade recorded, with global average temperature reaching 1.1°C above pre-industrial levels in 2019. Human-induced global warming is presently increasing at a rate of 0.2°C per decade.An increase of 2°C compared to the temperature in pre-industrial times is associated with serious negative impacts on to the natural environment and human health and wellbeing, including a much higher risk that dangerous and possibly catastrophic changes in the global environment will occur.For this reason, the international community has recognised the need to keep warming well below 2°C and pursue efforts to limit it to 1.5°C. Share this page
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                            [title] => Causes | Facts – Climate Change: Vital Signs of the Planet
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                            [description] => Vital Signs of the Planet: Global Climate Change and Global Warming. What is the “greenhouse effect”? What is causing it? Are humans to blame? What does solar irradiance have to do with it? Answers here
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                                            [title] => What is the greenhouse effect? - NASA Climate Change
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                            [serp_title] => Vital Signs of the Planet - Causes | Facts – Climate Change
                            [serp_description] => The panel also concluded there's a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide ...
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                                                    [text] => https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_summary-for-policymakers.pdf
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                            [body] => Facts The Causes of Climate Change › en español In Brief: . Human activities (primarily the burning of fossil fuels) have fundamentally increased the concentration of greenhouse gases in Earth’s atmosphere, warming the planet. Natural drivers, without human intervention, would push our planet toward a cooling period. Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the "greenhouse effect"1 — warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as "forcing" climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as "feedbacks." Gases that contribute to the greenhouse effect include: Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect. Carbon dioxide (CO2). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Humans have increased atmospheric CO2 concentration by 48% since the Industrial Revolution began. This is the most important long-lived "forcing" of climate change. Methane. A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide, but also one which is much less abundant in the atmosphere. Nitrous oxide. A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning. Chlorofluorocarbons (CFCs). Synthetic compounds entirely of industrial origin used in a number of applications, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. They are also greenhouse gases. Not enough greenhouse effect: The planet Mars has a very thin atmosphere, nearly all carbon dioxide. Because of the low atmospheric pressure, and with little to no methane or water vapor to reinforce the weak greenhouse effect, Mars has a largely frozen surface that shows no evidence of life. Too much greenhouse effect: The atmosphere of Venus, like Mars, is nearly all carbon dioxide. But Venus has about 154,000 times as much carbon dioxide in its atmosphere as Earth (and about 19,000 times as much as Mars does), producing a runaway greenhouse effect and a surface temperature hot enough to melt lead. On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases. The consequences of changing the natural atmospheric greenhouse are difficult to predict, but some effects seem likely: On average, Earth will become warmer. Some regions may welcome warmer temperatures, but others may not. Warmer conditions will probably lead to more evaporation and precipitation overall, but individual regions will vary, some becoming wetter and others dryer. A stronger greenhouse effect will warm the ocean and partially melt glaciers and ice sheets, increasing sea level. Ocean water also will expand if it warms, contributing further to sea level rise. Outside of a greenhouse, higher atmospheric carbon dioxide (CO2) levels can have both positive and negative effects on crop yields. Some laboratory experiments suggest that elevated CO2 levels can increase plant growth. However, other factors, such as changing temperatures, ozone, and water and nutrient constraints, may more than counteract anypotential increase in yield. If optimal temperature ranges for some crops are exceeded, earlier possible gains in yield may be reduced or reversed altogether. Climate extremes, such as droughts, floods and extreme temperatures, can lead to crop losses and threaten the livelihoods of agricultural producers and the food security of communities worldwide. Depending on the crop and ecosystem, weeds, pests, and fungi can also thrive under warmer temperatures, wetter climates, and increased CO2 levels, and climate change will likely increase weeds and pests. Finally, although rising CO2 can stimulate plant growth, research has shown that it can also reduce the nutritional value of most food crops by reducing the concentrations of protein and essential minerals in most plant species. Climate change can cause new patterns of pests and diseases to emerge, affecting plants, animals and humans, and posing new risks for food security, food safety and human health.2 The Role of Human Activity In its Fifth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there's a more than 95 percent probability that human activities over the past 50 years have warmed our planet. The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to about 417 parts per million in the last 151 years. The panel also concluded there's a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane and nitrous oxide have caused much of the observed increase in Earth's temperatures over the past 50-plus years. The panel's full Summary for Policymakers report is online at https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_summary-for-policymakers.pdf. Solar Irradiance. The above graph compares global surface temperature changes (red line) and the Sun's energy that Earth receives (yellow line) in watts (units of energy) per square meter since 1880. The lighter/thinner lines show the yearly levels while the heavier/thicker lines show the 11-year average trends. Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious. The amount of solar energy that Earth receives has followed the Sun’s natural 11-year cycle of small ups and downs with no net increase since the 1950s. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Credit: NASA/JPL-Caltech It's reasonable to assume that changes in the Sun's energy output would cause the climate to change, since the Sun is the fundamental source of energy that drives our climate system. Indeed, studies show that solar variability has played a role in past climate changes. For example, a decrease in solar activity coupled with an increase in volcanic activity is thought to have helped trigger the Little Ice Age between approximately 1650 and 1850, when Greenland cooled from 1410 to the 1720s and glaciers advanced in the Alps. But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun: Since 1750, the average amount of energy coming from the Sun either remained constant or increased slightly. If the warming were caused by a more active Sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. That's because greenhouse gases are trapping heat in the lower atmosphere. Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases. References. IPCC Fifth Assessment Report, 2014 United States Global Change Research Program, "Global Climate Change Impacts in the United States," Cambridge University Press, 2009 Naomi Oreskes, "The Scientific Consensus on Climate Change," Science 3 December 2004: Vol. 306 no. 5702 p. 1686 DOI: 10.1126/science.1103618 U.S. Environmental Protection Agency: "Climate Impacts on Agriculture and Food Supply" Mike Lockwood, “Solar Change and Climate: an update in the light of the current exceptional solar minimum,” Proceedings of the Royal Society A, 2 December 2009, doi 10.1098/rspa.2009.0519; Judith Lean, “Cycles and trends in solar irradiance and climate,” Wiley Interdisciplinary Reviews: Climate Change, vol. 1, January/February 2010, 111-122. Explore Interactives, galleries and apps. . Images of Change Explore a stunning gallery of before-and-after images of Earth from land and space that reveal our home planet in a state of flux. . Climate Time Machine Travel through Earth's recent climate history and see how increasing carbon dioxide, global temperature and sea ice have changed over time. . Eyes on the Earth Track Earth's vital signs from space and fly along with NASA's Earth-observing satellites in an interactive 3D visualization. . Global Ice Viewer Earth's ice cover is shrinking. See how climate change has affected glaciers, sea ice, and continental ice sheets.
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                            [description] => Carbon dioxide, a key greenhouse gas that drives global climate change, continues to rise every month. Find out the dangerous role it and other gases play
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                            [body] => Carbon dioxide levels are at a record high. Here's what you need to know.Carbon dioxide, a key greenhouse gas that drives global climate change, continues to rise every month. Find out the dangerous role it and other gases play.ByChristina NunezPublished May 13, 2019• 6 min readShareTweetEmailBy trapping heat from the sun, greenhouse gases have kept Earth's climate habitable for humans and millions of other species. But those gases are now out of balance and threaten to change drastically which living things can survive on this planet—and where.Atmospheric levels of carbon dioxide—the most dangerous and prevalent greenhouse gas—are at the highest levels ever recorded. Greenhouse gas levels are so high primarily because humans have released them into the air by burning fossil fuels. The gases absorb solar energy and keep heat close to Earth's surface, rather than letting it escape into space. That trapping of heat is known as the greenhouse effect.The roots of the greenhouse effect concept lie in the 19th century, when French mathematician Joseph Fourier calculated in 1824 that the Earth would be much colder if it had no atmosphere. In 1896, Swedish scientist Svante Arrhenius was the first to link a rise in carbon dioxide gas from burning fossil fuels with a warming effect. Nearly a century later, American climate scientist James E. Hansen testified to Congress that “The greenhouse effect has been detected and is changing our climate now."Today, climate change is the term scientists use to describe the complex shifts, driven by greenhouse gas concentrations, that are now affecting our planet’s weather and climate systems. Climate change encompasses not only the rising average temperatures we refer to as global warming but also extreme weather events, shifting wildlife populations and and habitats, rising seas, and a range of other impacts.Governments and organizations around the world such as the Intergovernmental Panel on Climate Change (IPCC), the United Nations body that tracks the latest climate change science, are measuring greenhouse gases, tracking their impacts, and implementing solutions.Major greenhouse gases and sources. Carbon dioxide (CO2): Carbon dioxide is the primary greenhouse gas, responsible for about three-quarters of emissions. It can linger in the atmosphere for thousands of years. In 2018, carbon dioxide levels reached 411 parts per million at Hawaii's Mauna Loa Atmospheric Baseline Observatory, the highest monthly average ever recorded. Carbon dioxide emissions mainly come from burning organic materials: coal, oil, gas, wood, and solid waste.Methane (CH4): The main component of natural gas, methane is released from landfills, natural gas and petroleum industries, and agriculture (especially from the digestive systems of grazing animals). A molecule of methane doesn't stay in the atmosphere as long as a molecule of carbon dioxide—about 12 years—but it is at least 84 times more potent over two decades. It accounts for about 16 percent of all greenhouse gas emissions.Nitrous Oxide (N2O): Nitrous oxide occupies a relatively small share of global greenhouse gas emissions—about six percent—but it is 264 times more powerful than carbon dioxide over 20 years, and its lifetime in the atmosphere exceeds a century, according to the IPCC. Agriculture and livestock, including fertilizer, manure, and burning of agricultural residues, along with burning fuel, are the biggest sources of nitrous oxide emissions.Industrial gases: Fluorinated gases such as hydrofluorocarbons, perfluorocarbons, chlorofluorocarbons, sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3) have heat-trapping potential thousands of times greater than CO2 and stay in the atmosphere for hundreds to thousands of years. Accounting for about 2 percent of all emissions, they're used as refrigerants, solvents, and in manufacturing, sometimes occurring as byproducts.Other greenhouse gases include water vapor and ozone (O3). Water vapor is actually the world's most abundant greenhouse gas, but it is not tracked the same way as other greenhouse gases because it is not directly emitted by human activity and its effects are not well understood. Similarly, ground-level or tropospheric ozone (not to be confused with the protective stratospheric ozone layer higher up) is not emitted directly but emerges from complex reactions among pollutants in the air.Effects of greenhouse gases. Greenhouse gases have far-ranging environmental and health effects. They cause climate change by trapping heat, and they also contribute to respiratory disease from smog and air pollution. Extreme weather, food supply disruptions, and increased wildfires are other effects of climate change caused by greenhouse gases. The typical weather patterns we've grown to expect will change; some species will disappear; others will migrate or grow. (Read more about greenhouse gas effects via climate change here.)How to reduce greenhouse gas emissions. Virtually every sector of the global economy, from manufacturing to agriculture to transportation to power production, contributes greenhouse gases to the atmosphere, so all of them must evolve away from fossil fuels if we are to avoid the worst effects of climate change. Countries around the world acknowledged this reality with the Paris Climate Agreement of 2015. The changes will be most important among the biggest emitters: Twenty countries are responsible for at least three-quarters of the world's greenhouse gas emissions, with China, the United States, and India leading the way.The technologies for ramping down greenhouse gas emissions already exist, for the most part. They include swapping fossil fuels for renewable sources, boosting energy efficiency, and discouraging carbon emissions by putting a price on them. (Read more about such solutions here.)The world technically has only one-fifth of its "carbon budget"—the total is 2.8 trillion metric tons—remaining in order to avoid warming the Earth more than 1.5 degrees Celsius. Halting the trends in motion will require more than just phasing out fossil fuels. In fact, the paths to halting global temperature increases of 1.5 or 2 degrees C, the two goals outlined by the IPCC, rely in some way on adopting methods of sucking CO2 from the sky. Those include planting trees, conserving existing forests and grasslands, and capturing CO2 from power plants and factories.ShareTweetEmailRead This Next. 9 big questions about Omicron explainedScienceCoronavirus Coverage9 big questions about Omicron explained. Why is the CDC changing its isolation guidance? Which type of test is best? And how long should you isolate or quarantine? Experts weigh in to help clear confusion.Cubans turn to natural remedies in midst of drug shortageHistory & CultureCoronavirus CoverageCubans turn to natural remedies in midst of drug shortage. With prescription drugs in short supply in Cuba herbal remedies and other alternative treatments have become increasingly important.Pig brain cells may have cured a sea lion's epilepsySciencePig brain cells may have cured a sea lion's epilepsy. The transplant in an animal named Cronutt points toward a new strategy to treat the disease. But many questions remain.9 must-see stargazing events to watch in 2022Science9 must-see stargazing events to watch in 2022. The year ahead offers many heavenly delights for sky-watchers, including two blood moons, a pair of partial solar eclipses, and multiple planetary meetings.Go Further. Animals. Rescues of rare Philippine eagles soar during the pandemicAnimalsRescues of rare Philippine eagles soar during the pandemicIn Indonesia, orangutan killings often go unpunishedAnimalsWildlife WatchIn Indonesia, orangutan killings often go unpunishedBiologist who coined ‘biological diversity’ dies at 80AnimalsBiologist who coined ‘biological diversity’ dies at 80Tiger King zoo owner now banned from exhibiting animalsAnimalsWildlife WatchTiger King zoo owner now banned from exhibiting animalsNew megadams threaten world’s biggest fishAnimalsNew megadams threaten world’s biggest fishThese ghostly sea creatures make snow glow in the ArcticAnimalsThese ghostly sea creatures make snow glow in the ArcticEnvironment. A rising tide is drowning Indonesian villages—and their deadEnvironmentA rising tide is drowning Indonesian villages—and their deadAn imported tree fuels Patagonia’s terrifying summer firesEnvironmentAn imported tree fuels Patagonia’s terrifying summer firesUnderstand how Hong Kong’s coral communities have declinedPaid ContentUnderstand how Hong Kong’s coral communities have declinedA national 'climate corps'? California is leading the wayEnvironmentPlanet PossibleA national 'climate corps'? California is leading the wayHow small changes to our diet can benefit the planetEnvironmentPlanet PossibleHow small changes to our diet can benefit the planetCould crushed rocks absorb enough carbon to curb global warming?EnvironmentPlanet PossibleCould crushed rocks absorb enough carbon to curb global warming?History & Culture. The mystery of Iran's Luristan BronzesHistory MagazineThe mystery of Iran's Luristan BronzesPlessy v. Ferguson aimed to end segregation—but codified it insteadHistory & CulturePlessy v. Ferguson aimed to end segregation—but codified it insteadThe Lighthouse of Alexandria shone for more than a thousand yearsHistory MagazineThe Lighthouse of Alexandria shone for more than a thousand years3,600-year-old tsunami 'time capsule' discovered in AegeanHistory & Culture3,600-year-old tsunami 'time capsule' discovered in AegeanThe pandemic delivered a surprise to Nordic countries: a baby boomHistory & CultureThe pandemic delivered a surprise to Nordic countries: a baby boomThe new year once started in March—here's whyHistory & CultureThe new year once started in March—here's whyScience. NASA's most powerful space telescope finishes risky unfoldingScienceNASA's most powerful space telescope finishes risky unfoldingSee spectacular fossils from a prehistoric rainforestScienceSee spectacular fossils from a prehistoric rainforestCDC expands booster eligibility to include teens ages 12 to 15ScienceCoronavirus CoverageCDC expands booster eligibility to include teens ages 12 to 159 big questions about Omicron explainedScienceCoronavirus Coverage9 big questions about Omicron explainedPig brain cells may have cured a sea lion's epilepsySciencePig brain cells may have cured a sea lion's epilepsyRichard Leakey, conservationist and fossil hunter, dies at 77ScienceRichard Leakey, conservationist and fossil hunter, dies at 77Travel. Ancient Rome brought to life along Hadrian’s WallTravelWorld HeritageAncient Rome brought to life along Hadrian’s WallDiscover the beauty of U.S. national parks in winterTravelDiscover the beauty of U.S. national parks in winter17 stellar new hotels that embrace their geographyTravel17 stellar new hotels that embrace their geographyThis ancient city of sultans is a 21st-century wonderTravelBest of the WorldThis ancient city of sultans is a 21st-century wonderHow these Japanese prayer plaques became symbols of hopeTravelHow these Japanese prayer plaques became symbols of hopeHere’s the best spot on Earth to see polar bears in the wildTravelHere’s the best spot on Earth to see polar bears in the wildSubscriber Exclusive Content. previousMagazineWhy are people so dang obsessed with Mars?ReadMagazineHow viruses shape our world. ReadAnimalsThe era of greyhound racing in the U.S. is coming to an end. ReadMagazineSee how people have imagined life on Mars through history. ReadMagazineSee how NASA’s new Mars rover will explore the red planet. ExploreMagazineWhy are people so dang obsessed with Mars?ReadMagazineHow viruses shape our world. ReadAnimalsThe era of greyhound racing in the U.S. is coming to an end. ReadMagazineSee how people have imagined life on Mars through history. ReadMagazineSee how NASA’s new Mars rover will explore the red planet. ExploreMagazineWhy are people so dang obsessed with Mars?ReadMagazineHow viruses shape our world. ReadAnimalsThe era of greyhound racing in the U.S. is coming to an end. ReadMagazineSee how people have imagined life on Mars through history. ReadMagazineSee how NASA’s new Mars rover will explore the red planet. Explorenext See MoreLegal. Terms of UsePrivacy PolicyYour California Privacy RightsChildren's Online Privacy PolicyInterest-Based AdsAbout Nielsen MeasurementDo Not Sell My InfoOur Sites. Nat Geo HomeAttend a Live EventBook a TripBuy MapsInspire Your KidsShop Nat GeoVisit the D.C. 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                            [body] => Climate Change Indicators: Greenhouse Gases View Indicators:. Greenhouse gases from human activities are the most significant driver of observed climate change since the mid-20th century.1 The indicators in this chapter characterize emissions of the major greenhouse gases resulting from human activities, the concentrations of these gases in the atmosphere, and how emissions and concentrations have changed over time. When comparing emissions of different gases, these indicators use a concept called “global warming potential” to convert amounts of other gases into carbon dioxide equivalents. Why does it matter? As greenhouse gas emissions from human activities increase, they build up in the atmosphere and warm the climate, leading to many other changes around the world—in the atmosphere, on land, and in the oceans. The indicators in other chapters of this report illustrate many of these changes, which have both positive and negative effects on people, society, and the environment—including plants and animals. Because many of the major greenhouse gases stay in the atmosphere for tens to hundreds of years after being released, their warming effects on the climate persist over a long time and can therefore affect both present and future generations. Summary of Key Points. U.S. Greenhouse Gas Emissions. In the United States, greenhouse gas emissions caused by human activities increased by 2 percent from 1990 to 2019. Since 2005, however, total U.S. greenhouse gas emissions have decreased by 12 percent. Carbon dioxide accounts for most of the nation’s emissions and most of the increase since 1990. Transportation is the largest source of greenhouse gas emissions in the United States, followed by electricity generation. Emissions per person have decreased slightly in the last few years. Sources of Data on U.S. Greenhouse Gas Emissions. EPA has two key programs that provide data on greenhouse gas emissions in the United States: the Inventory of U.S. Greenhouse Gas Emissions and Sinks and the Greenhouse Gas Reporting Program. The programs are complementary, providing both a higher-level perspective on the nation’s total emissions and detailed information about the sources and types of emissions from individual facilities. Global Greenhouse Gas Emissions. Worldwide, net emissions of greenhouse gases from human activities increased by 43 percent from 1990 to 2015. Emissions of carbon dioxide, which account for about three-fourths of total emissions, increased by 51 percent over this period. As with the United States, the majority of the world’s emissions result from transportation, electricity generation, and other forms of energy production and use. Atmospheric Concentrations of Greenhouse Gases. Concentrations of carbon dioxide and other greenhouse gases in the atmosphere have increased since the beginning of the industrial era. Almost all of this increase is attributable to human activities.2 Historical measurements show that the current global atmospheric concentrations of carbon dioxide are unprecedented compared with the past 800,000 years, even after accounting for natural fluctuations. Climate Forcing. Climate forcing refers to a change in the Earth’s energy balance, leading to either a warming or cooling effect over time. An increase in the atmospheric concentrations of greenhouse gases produces a positive climate forcing, or warming effect. From 1990 to 2019, the total warming effect from greenhouse gases added by humans to the Earth’s atmosphere increased by 45 percent. The warming effect associated with carbon dioxide alone increased by 36 percent. Major Long-Lived Greenhouse Gases and Their Characteristics. Greenhouse gas How it's produced Average lifetime in the atmosphere 100-year global warming potential Carbon dioxide Emitted primarily through the burning of fossil fuels (oil, natural gas, and coal), solid waste, and trees and wood products. Changes in land use also play a role. Deforestation and soil degradation add carbon dioxide to the atmosphere, while forest regrowth takes it out of the atmosphere.  see below* 1 Methane Emitted during the production and transport of oil and natural gas as well as coal. Methane emissions also result from livestock and agricultural practices and from the anaerobic decay of organic waste in municipal solid waste landfills.  12.4 years** 28–36 Nitrous oxide Emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.  121 years** 265–298 Fluorinated gases A group of gases that contain fluorine, including hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, among other chemicals. These gases are emitted from a variety of industrial processes and commercial and household uses and do not occur naturally. Sometimes used as substitutes for ozone-depleting substances such as chlorofluorocarbons.  A few weeks to thousands of years Varies (the highest is sulfur hexafluoride at 23,500) This table shows 100-year global warming potentials, which describe the effects that occur over a period of 100 years after a particular mass of a gas is emitted. Global warming potentials and lifetimes come from Table 8.A.1 of the Intergovernmental Panel on Climate Change’s Fifth Assessment Report, Working Group I contribution.3 * Carbon dioxide’s lifetime cannot be represented with a single value because the gas is not destroyed over time, but instead moves among different parts of the ocean–atmosphere–land system. Some of the excess carbon dioxide is absorbed quickly (for example, by the ocean surface), but some will remain in the atmosphere for thousands of years, due in part to the very slow process by which carbon is transferred to ocean sediments. ** The lifetimes shown for methane and nitrous oxide are perturbation lifetimes, which have been used to calculate the global warming potentials shown here. Sources of Data on U.S. Greenhouse Gas Emissions. EPA has two key programs that provide data on greenhouse gas emissions in the United States: the Inventory of U.S. Greenhouse Gas Emissions and Sinks and the Greenhouse Gas Reporting Program. The programs are complementary, providing both a higher-level perspective on the nation’s total emissions and detailed information about the sources and types of emissions from individual facilities. The data in EPA’s U.S. Greenhouse Gas Emissions indicator come from the national inventory. EPA's Inventory of Greenhouse Gas Emissions and Sinks. EPA develops an annual report called the Inventory of U.S. Greenhouse Gas Emissions and Sinks (or the GHG Inventory). This report tracks trends in total annual U.S. emissions by source (or sink), economic sector, and greenhouse gas going back to 1990. EPA uses national energy data, data on national agricultural activities, and other national statistics to provide a comprehensive accounting of total greenhouse gas emissions for all man-made sources in the United States. This inventory fulfills the nation’s obligation to provide an annual emissions report under the United Nations Framework Convention on Climate Change. Learn more about the inventory and explore the data using interactive tools. EPA's Greenhouse Gas Reporting Program. Since 2010, EPA’s Greenhouse Gas Reporting Program has been collecting annual emissions data from industrial sources that directly emit large amounts of greenhouse gases. Generally, facilities that emit more than 25,000 metric tons of carbon dioxide equivalents per year are required to report. The program also collects data from entities known as "suppliers" that supply certain fossil fuels and industrial gases that will emit greenhouse gases into the atmosphere if burned or released—for example, refineries that supply petroleum products such as gasoline. The Greenhouse Gas Reporting Program only requires reporting; it is not an emissions control program. This program helps EPA and the public understand where greenhouse gas emissions are coming from, and will improve our ability to make informed policy, business, and regulatory decisions. Learn more about the Greenhouse Gas Reporting Program and explore data by facility, industry, location, or gas using a data visualization and mapping tool called FLIGHT. You can also review state- or tribal-specific emissions using interactive fact sheets and download detailed data via EPA's Envirofacts database.  References. 1 IPCC (Intergovernmental Panel on Climate Change). 2013. Climate change 2013: The physical science basis. Working Group I contribution to the IPCC Fifth Assessment Report. Cambridge, United Kingdom: Cambridge University Press. www.ipcc.ch/report/ar5/wg1. 2 IPCC (Intergovernmental Panel on Climate Change). 2013. Climate change 2013: The physical science basis. Working Group I contribution to the IPCC Fifth Assessment Report. Cambridge, United Kingdom: Cambridge University Press. www.ipcc.ch/report/ar5/wg1. 3 IPCC (Intergovernmental Panel on Climate Change). 2013. Climate change 2013: The physical science basis. Working Group I contribution to the IPCC Fifth Assessment Report. Cambridge, United Kingdom: Cambridge University Press. www.ipcc.ch/report/ar5/wg1. Climate Change Indicators Greenhouse Gases U.S. Greenhouse Gas Emissions Global Greenhouse Gas Emissions Atmospheric Concentrations of Greenhouse Gases Climate Forcing Weather and Climate Oceans Snow and Ice Health and Society Ecosystems Frequent Questions Contact Us to ask a question, provide feedback, or report a problem.
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                            [body] => Greenhouse Effect 101 By increasing the concentration of greenhouse gases in the atmosphere, we’re amplifying the planet’s natural greenhouse effect and turning up the dial on global warming. July 16, 2019 Melissa Denchak Jump to Section What Is the Greenhouse Effect? What Causes the Greenhouse Effect? What Are Greenhouse Gases? The Consequences of the Greenhouse Effect The Greenhouse Effect Solution The greenhouse effect is a good thing. It warms the planet to its comfortable average of 59 degrees Fahrenheit (15 degrees Celsius) and keeps life on earth, well, livable. Without it the world would be a frozen, uninhabitable place, more like Mars. The problem is, mankind’s voracious burning of fossil fuels for energy is artificially amping up the natural greenhouse effect. The result? An increase in global warming that is altering the planet’s climate systems in countless ways. Here’s a look at what the greenhouse effect is, what causes it, and how we can temper its contributions to our changing climate. What Is the Greenhouse Effect? Identified by scientists as far back as 1896, the greenhouse effect is the natural warming of the earth that results when gases in the atmosphere trap heat from the sun that would otherwise escape into space. What Causes the Greenhouse Effect? Sunlight makes the earth habitable. While 30 percent of the solar energy that reaches our world is reflected back to space, approximately 70 percent passes through the atmosphere to the earth’s surface, where it is absorbed by the land, oceans, and atmosphere, and heats the planet. This heat is then radiated back up in the form of invisible infrared light. While some of this infrared light continues on into space, the vast majority—indeed, some 90 percent—gets absorbed by atmospheric gases, known as greenhouse gases, and redirected back toward the earth, causing further warming.For most of the past 800,000 years—much longer than human civilization has existed—the concentration of greenhouse gases in our atmosphere was between about 200 and 280 parts per million. (In other words, there were 200 to 280 molecules of the gases per million molecules of air.) But in the past century, that concentration has jumped to more than 400 parts per million, driven up by human activities such as burning fossil fuels and deforestation. The higher concentrations of greenhouse gases—and carbon dioxide in particular—is causing extra heat to be trapped and global temperatures to rise. Michal Bednarski for NRDC What Are Greenhouse Gases? Earth’s greenhouse gases trap heat in the atmosphere and warm the planet. The main gases responsible for the greenhouse effect include carbon dioxide, methane, nitrous oxide, and water vapor (which all occur naturally), and fluorinated gases (which are synthetic). Greenhouse gases have different chemical properties and are removed from the atmosphere, over time, by different processes. Carbon dioxide, for example, is absorbed by so-called carbon sinks such as plants, soil, and the ocean. Fluorinated gases are destroyed only by sunlight in the far upper atmosphere.How much any one greenhouse gas influences global warming depends on three key factors. The first is how much of it exists in the atmosphere. Concentrations are measured in parts per million (ppm), parts per billion (ppb), or parts per trillion (ppt); 1 ppm for a given gas means, for example, that there is one molecule of that gas in every 1 million molecules of air. The second is its lifetime—how long it remains in the atmosphere. The third is how effective it is at trapping heat. This is referred to as its global warming potential, or GWP, and is a measure of the total energy that a gas absorbs over a given period of time (usually 100 years) relative to the emissions of 1 ton of carbon dioxide.Radiative forcing (RF) is another way to measure greenhouse gases (and other climate drivers, such as the sun’s brightness and large volcanic eruptions). Also known as climate forcing, RF quantifies the difference between how much of the sun’s energy gets absorbed by the earth and how much is released into space as a result of any one climate driver. A climate driver with a positive RF value indicates that it has a warming effect on the planet; a negative value represents cooling.What Are Greenhouse Gas Emissions?Since the start of the Industrial Revolution and the advent of coal-powered steam engines, human activities have vastly increased the volume of greenhouse gases emitted into the atmosphere. It is estimated that between 1750 and 2011, atmospheric concentrations of carbon dioxide increased by 40 percent, methane by 150 percent, and nitrous oxide by 20 percent. In the late 1920s, we started adding man-made fluorinated gases like chlorofluorocarbons, or CFCs, to the mix.In recent decades we’ve only picked up the pace. Of all the man-made emissions of carbon dioxide—the most abundant greenhouse gas released by human activities, and one of the longest-lasting—from 1750 to 2010, approximately half were generated in the last 40 years alone, in large part due to fossil fuel combustion and industrial processes. And while global greenhouse gas emissions have occasionally plateaued or dropped from year to year (most recently between 2014 and 2016), they’re accelerating once again. In 2017, carbon emissions rose by 1.6 percent; in 2018 they increased by an estimated 2.7 percent.  Five Major Greenhouse Gases. The most significant gases that cause global warming via the greenhouse effect are the following:Carbon DioxideAccounting for about 76 percent of global human-caused emissions, carbon dioxide (CO2) sticks around for quite a while. Once it’s emitted into the atmosphere, 40 percent still remains after 100 years, 20 percent after 1,000 years, and 10 percent as long as 10,000 years later.MethaneAlthough methane (CH4) persists in the atmosphere for far less time than carbon dioxide (about a decade), it is much more potent in terms of the greenhouse effect. In fact, pound for pound, its global warming impact is 25 times greater than that of carbon dioxide over a 100-year period. Globally it accounts for approximately 16 percent of human-generated greenhouse gas emissions.Nitrous OxideNitrous oxide (N2O) is a powerful greenhouse gas: It has a GWP 300 times that of carbon dioxide on a 100-year time scale, and it remains in the atmosphere, on average, a little more than a century. It accounts for about 6 percent of human-caused greenhouse gas emissions worldwide.Fluorinated GasesEmitted from a variety of manufacturing and industrial processes, fluorinated gases are man-made. There are four main categories: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3).Although fluorinated gases are emitted in smaller quantities than other greenhouse gases (they account for just 2 percent of man-made global greenhouse gas emissions), they trap substantially more heat. Indeed, the GWP for these gases can be in the thousands to tens of thousands, and they have long atmospheric lifetimes, in some cases lasting tens of thousands of years.HFCs are used as a replacement for ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), usually in air conditioners and refrigerators, but some are being phased out because of their high GWP. Replacing these HFCs and properly disposing of them is considered to be one of the most important climate actions the world can take.Water VaporThe most abundant greenhouse gas overall, water vapor differs from other greenhouse gases in that changes in its atmospheric concentrations are linked not to human activities directly, but rather to the warming that results from the other greenhouse gases we emit. Warmer air holds more water. And since water vapor is a greenhouse gas, more water absorbs more heat, inducing even greater warming and perpetuating a positive feedback loop. (It’s worth noting, however, that the net impact of this feedback loop is still uncertain, as increased water vapor also increases cloud cover that reflects the sun’s energy away from the earth.) Big Bend Power Station, a coal-fired power plant in Tampa, Florida Walter via Flickr Where Do Greenhouse Gases Come From?Population size, economic activity, lifestyle, energy use, land use patterns, technology, and climate policy: According to the Intergovernmental Panel on Climate Change (IPCC), these are the broad forcings that drive nearly all human-caused greenhouse gas emissions. Here’s a closer look at greenhouse gas emissions by source.Electricity and Heat ProductionThe burning of coal, oil, and natural gas to produce electricity and heat accounts for one-quarter of worldwide human-driven emissions, making it the largest single source. In the United States it’s the second-largest (behind transportation), responsible for about 27.5 percent of U.S. emissions in 2017, with carbon dioxide the primary gas released (along with small amounts of methane and nitrous oxide), mainly from coal combustion.Agriculture and Land Use ChangesAbout another quarter of global greenhouse gas emissions stem from agriculture and other land-use activities (such as deforestation). In the United States, agricultural activities—primarily the raising of livestock and crops for food—accounted for 8.4 percent of greenhouse gas emissions in 2017. Of those, the vast majority were methane (which is produced as manure decomposes and as beef and dairy cows belch and pass gas) and nitrous oxide (often released with the use of nitrogen-heavy fertilizers).Trees, plants, and soil absorb carbon dioxide from the air. The plants and trees do it via photosynthesis (a process by which they turn carbon dioxide into glucose); the soil houses microbes that carbon binds to. So nonagricultural land-use changes such as deforestation, reforestation (replanting in existing forested areas), and afforestation (creating new forested areas) can either increase the amount of carbon in the atmosphere (as in the case of deforestation) or decrease it via absorption, removing more carbon dioxide from the air than they emit. (When trees or plants are cut down, they no longer absorb carbon dioxide, and when they are burned or decompose, they release carbon dioxide back into the atmosphere.) In the United States, land-use activities currently represent a net carbon sink, absorbing more carbon dioxide from the air than they emit.IndustryAbout one-fifth of global human-driven emissions come from the industrial sector, which includes the manufacturing of goods and raw materials (like cement and steel), food processing, and construction. In 2017, industry accounted for 22.4 percent of U.S. man-made emissions, of which the majority was carbon dioxide, though methane, nitrous oxide, and fluorinated gases were also released. Jingying Zhao/Getty TransportationThe burning of petroleum-based fuels, namely gasoline and diesel, to power the world’s transportation systems accounts for 14 percent of global greenhouse gas emissions. In the United States, with Americans buying larger cars and taking more flights and with low gas prices encouraging drivers to use their cars more, transportation is the largest contributor of greenhouse gases. (It accounted for 28.7 percent of U.S. emissions in 2017.) Carbon dioxide is the primary gas emitted, though fuel combustion also releases small amounts of methane and nitrous oxide, and vehicle air conditioning and refrigerated transport release fluorinated gases too.Nationwide, cars and trucks are responsible for more than 80 percent of transportation-related carbon emissions.BuildingsOperating buildings around the world generates 6.4 percent of global greenhouse gases. In the United States, homes and businesses accounted for about 11 percent of warming emissions. These emissions, made up mostly of carbon dioxide and methane, stem primarily from burning natural gas and oil for heating and cooking, though other sources include managing waste and wastewater and leaking refrigerants from air-conditioning and refrigeration systems.Other SourcesThis category includes emissions from energy-related activities other than fossil fuel combustion, such as the extraction, refining, processing, and transportation of oil, gas, and coal. Globally, this sector accounts for 9.6 percent of emissions.Greenhouse Gas Emissions by Country. Since the start of the Industrial Revolution, more than 2,000 billion tons of carbon dioxide have been released into the atmosphere by human activities, according to the Global Carbon Project. North America and Europe are responsible for approximately half of that total, while the emerging economies of China and India have contributed another 14 percent. For the remainder, 150-plus countries share responsibility.An analysis of carbon dioxide emissions by country today shows that China now leads the pack, responsible for 27 percent of all emissions. Next comes the United States (15 percent), the European Union’s 28 member states including the United Kingdom (10 percent), and India (7 percent) next. Together, these global powers account for almost 60 percent of all emissions.  People receive water from a tanker on a hot day in Allahabad, India. Sanjay Kanojia/AFP/Getty The Consequences of the Greenhouse Effect. Today’s human-caused greenhouse gas emissions are higher than ever, the concentration of greenhouse gases in the atmosphere is rising rapidly, and according to the IPCC, the planet is heating up. Between preindustrial times and now, the earth’s average temperature has increased 1.8 degrees Fahrenheit (1.0 degrees Celsius), with approximately two-thirds of that warming occurring in the last handful of decades alone. According to the IPCC, 1983 to 2012 was likely the warmest 30-year period of the last 1,400 years (in the Northern Hemisphere, where assessment is possible). And all five of the years from 2014 to 2018 were the hottest on record globally. If warming trends continue at the current rate, it’s estimated global warming will reach 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels between 2030 and 2052.Fueled by man-made greenhouse gas emissions, global warming is altering the earth’s climate systems in many ways. It is:Causing more frequent and/or intense extreme weather events, including heat waves, hurricanes, droughts, and floods.Exacerbating precipitation extremes, making wet regions wetter and dry regions drier.Raising sea levels due to melting glaciers and sea ice and an increase in ocean temperatures (warmer water expands, which can contribute to sea level rise).Altering ecosystems and natural habitat, shifting the geographic ranges, seasonal activities, migration patterns, and abundance of land, freshwater, and marine species.These changes pose threats not only to plants and wildlife, but directly to people. Warmer temperatures mean insects that spread diseases like dengue fever and Zika can thrive—and heat waves are getting hotter and more lethal to humans. People could go hungry when our food supply is diminished thanks to droughts and floods—a 2011 National Research Council study found that for every degree Celsius that the planet heats up, crop yields will go down 5 to 15 percent. Food insecurity can lead to mass human migration and political instability. And in January 2019, the Department of Defense released a report that described the threats to U.S. military installations and operations around the world due to flooding, droughts, and other impacts of climate change. A solar array and wind turbine at the National Wind Technology Center in Jefferson County, Colorado Dennis Schroeder/NREL The Greenhouse Effect Solution. The earth has always experienced warm and cool phases, with natural forces—from the sun’s intensity, volcanic eruptions, and natural changes in greenhouse gas concentrations—affecting how much energy from the sun our planet absorbs. Scientists say that as recently as a couple of centuries ago, the planet underwent a “Little Ice Age,” caused by a decrease in solar activity and an increase in volcanic activity. But today’s climatic warming—particularly the increase in temperatures since the mid-20th century—is occurring at a pace that can’t be explained by natural causes alone. According to NASA, “natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades.”In other words, humans are the problem. But we may also be the solution. We have the ability to rein in greenhouse gas emissions, though doing so certainly won’t be easy. Overhauling our energy systems will require transformative, aggressive global action—and now. According to the IPCC, we must decrease greenhouse gas pollution by 45 percent from 2010 levels by 2030 and reach net zero emissions by 2050. To allow global warming to exceed 1.5 degrees Celsius (which the IPCC has identified as the threshold for avoiding climate change’s worst impacts) would mean more intense drought, extreme heat, flooding, and poverty, the decline of species (including a mass die-off of the world’s coral reefs), and the worsening of food shortages and wildfires.Reducing our greenhouse gas emissions will require significant effort at the international, national, and local levels. First and foremost, we must slash fossil fuel production, consumption, and pollution by ramping up our use of clean, renewable energy and energy-efficient technologies and by investing in fuel-efficient and electric vehicles. We must end fossil fuel subsidies and better leverage “cap and invest” programs, carbon pricing, and carbon capture, storage, and utilization technologies (which catch the carbon dioxide from emissions sources like power plants or directly from the air and permanently bury it underground or convert it into other materials). We must protect our carbon-storing forests and reduce food waste and the emissions that go with it. And as individuals, we must commit to taking carbon-cutting actions in our daily lives.Currently the United States faces the additional hurdle of an administration doubling down on fossil fuel use by rolling back standards aimed at reducing emissions from dirty power plants and cars and trucks (in other words, from the electricity and transportation sectors, the nation’s two largest sources of greenhouse gas emissions). President Trump is also working to withdraw the nation from the landmark 2015 Paris climate agreement even though nearly two-thirds of Americans believe we should do more to tackle climate change, not less.Still, decision makers, companies, leaders, and activists across the country and around the world staunchly believe we must act on climate change. For just as the emissions of man-made greenhouse gases long ago are inducing the climate change we see now, the emissions we release today will impact us long into the future. Related Stories. Southwest Dispatch How Austin Plans to Grow—Without Adding More Cars to Its Roads. By tackling transit, ride sharing, and more, the Texas capital hopes to embrace its big-city identity. Q&A Global Warming 101. Everything you wanted to know about our changing climate but were too afraid to ask. Guide Fossil Fuels: The Dirty Facts. Mining, drilling, and burning dirty energy are harming the environment and our health. Here’s everything you need to know about fossil fuels, and why we need to embrace a clean energy future. onEarth Story The “Big Tent” of People Who Want Climate Action Just Keeps Getting Bigger. How much longer can politicians pretend that it’s a divisive issue? onEarth Story Mo Methane, Mo Problems. When it comes to harmful greenhouse gases, methane’s some pretty potent stuff. Here’s why. Drawing Out the Science Less Carbon, More Money . A recent climate assessment raised red flags about a shrinking economy. But maybe it doesn’t have to play out that way for millennials—we can start demanding with our dollars for a green, just economy. onEarth Story Trump’s Pick to Lead His New Climate Change Panel Says CO2 Has Been “Demonized” . The appointment of William Happer shows that as public opinion and government reports increasingly back climate science, deniers (including the president) are getting desperate. Western Dispatch Could Our Farms Become the World’s Great Untapped Carbon Sink? Carbon farming, an agricultural movement taking root in Northern California, aims to improve the soil and help stabilize the climate. Explainer Are the Effects of Global Warming Really that Bad? Short answer: Yes. Even a seemingly slight average temperature rise is enough to cause a dramatic transformation of our planet. Guide The IPCC Climate Change Report: Why It Matters to Everyone on the Planet . The U.N. report warns that dire impacts from climate change will arrive sooner than many expected. Here’s why we need to follow the report’s advice, and why every ton of emissions reductions can make a difference. Support Our Work. Join Us. When you sign up you'll become a member of NRDC's Activist Network. We will keep you informed with the latest alerts and progress reports. © Natural Resources Defense Council 2022 Privacy Policy State Disclosures
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                            [body] => The greenhouse effect Discovering Geology — Climate change Share this articleFacebookTwitterPinterestWhatsAppEmailCopy Link ‘Greenhouse gases’ are crucial to keeping our planet at a suitable temperature for life. Without the natural greenhouse effect, the heat emitted by the Earth would simply pass outwards from the Earth’s surface into space and the Earth would have an average temperature of about -20°C. Greenhouse gases. The greenhouse effect: some of the infrared radiation from the Sun passes through the atmosphere, but most is absorbed and re-emitted in all directions by greenhouse gas molecules and clouds. The effect of this is to warm the Earth’s surface and the lower atmosphere. A greenhouse gas is called that because it absorbs infrared radiation from the Sun in the form of heat, which is circulated in the atmosphere and eventually lost to space. Greenhouse gases also increase the rate at which the atmosphere can absorb short-wave radiation from the Sun, but this has a much weaker effect on global temperatures. The CO2 released from the burning of fossil fuels is accumulating as an insulating blanket around the Earth, trapping more of the Sun’s heat in our atmosphere. Actions carried out by humans are called anthropogenic actions; the anthropogenic release of CO2 contributes to the current enhanced greenhouse effect[1]. Which gases cause the greenhouse effect? . The contribution that a greenhouse gas makes to the greenhouse effect depends on how much heat it absorbs, how much it re-radiates and how much of it is in the atmosphere. In descending order, the gases that contribute most to the Earth’s greenhouse effect are: water vapour (H2O)carbon dioxide (CO2)nitrous oxide(N2O)methane (CH4)ozone (O3) In terms of the amount of heat these gases can absorb and re-radiate (known as their global warming potential or GWP), CH4 is 23 times more effective and N2O is 296 times more effective than CO2. However, there is much more CO2 in the Earth’s atmosphere than there is CH4 or N2O. Not all the greenhouse gas that we emit to the atmosphere remains there indefinitely. For example, the amount of CO2 in the atmosphere and the amount of CO2 dissolved in surface waters of the oceans stay in equilibrium, because the air and water mix well at the sea surface. When we add more CO2 to the atmosphere, a proportion of it dissolves into the oceans. Anthropogenic greenhouse gases . Since the start of the Industrial Revolution in the mid-18th century, human activities have greatly increased the concentrations of greenhouse gases in the atmosphere. Consequently, measured atmospheric concentrations of CO2 are many times higher than pre-industrial levels. Overview of global anthropogenic greenhouse gas emissions in 2017; figures here are expressed in CO2-equivalents. Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2015 (EPA, 2017). Main sources of anthropogenic greenhouse gases . Burning fossil fuels Carbon dioxide levels are substantially higher now than at any time in the last 750 000 years. The burning of fossil fuels has elevated CO2 levels from an atmospheric concentration of approximately 280 parts per million (ppm) in pre-industrial times to over 400 ppm in 2018. This is a 40 per cent increase since the start of the Industrial Revolution. CO2 concentrations are increasing at a rate of about 2–3 ppm/year and are expected to exceed 900 ppm by the end of the 21st century. If this continues, together with rising emissions of CH4 and other greenhouse gases, by 2100 the global average surface temperature could have increased by up to 4.8°C compared to pre-industrial levels. Consequently, some scientists suggest goals to limit concentrations to keep temperature change below +2°C.  This would include substantial cuts in anthropogenic greenhouse gas emissions by the middle of the 21st century through large-scale changes in energy systems and land use. In 2010, the burning of coal, natural gas and oil for electricity and heat was the largest single source of global greenhouse gas emissions (25 per cent). By comparison, in 2010, 14 per cent of global greenhouse gas emissions came from fossil fuels burned for road, rail, air and marine transportation. Agriculture, forestry and other land use Agriculture, deforestation and other changes in land use account for one quarter of net anthropogenic greenhouse gas emissions. According to a United Nations report, livestock is responsible for about 14.5 per cent of this. The main sources of emissions are: feed production and processing (45 per cent) outputs of greenhouse gases during digestion by cows (39 per cent) manure decomposition (10 per cent   The rest is attributable to the processing and transportation of animal products. Higher concentrations of atmospheric CH4 are also caused by changes in land and wetland use, pipeline losses and landfill emissions. The use of fertilisers can also lead to higher N2O concentrations. Agriculture is estimated to be the main driver for around 80 per cent of deforestation worldwide. Source: Pixabay. Cement manufacture Cement manufacture contributes CO2 to the atmosphere when calcium carbonate is heated, producing lime and CO2. Estimates vary, but it is widely accepted that the cement industry produces between five and eight per cent of global anthropogenic CO2 emissions, of which 50 per cent is produced from the chemical process itself and 40 per cent from burning fuel to power that process. The amount of CO2 emitted by the cement industry is more than 900 kg of CO2 for every 1000 kg of cement produced. A cement works in Clitheroe. The cement industry produces around five per cent of global anthropogenic CO2 emissions. © Alan Murray-Rust. Aerosols Aerosols are small particles suspended in the atmosphere that can be produced when we burn fossil fuels. Other anthropogenic sources of aerosols include pollution from cars and factories, chlorofluorocarbons (CFCs) used in refrigeration systems and CFCs and halons used in fire suppression systems and manufacturing processes. Aerosols can also be produced naturally from a number of natural processes e.g. forest fires, volcanoes and isoprene emitted from plants. We know that greenhouse gases provide a warming effect to Earth’s surface, but aerosol pollution in the atmosphere can counteract this warming effect. For example, sulphate aerosols from fossil fuel combustion exert a cooling influence by reducing the amount of sunlight that reaches the Earth. Aerosols also have a detrimental impact on human health and affect other parts of the climate system, such as rainfall. Volcanic ash dunes of Tarvurvur, Papua New Guinea. Sea salt, dust and volcanic ash are three common types of aerosols. Aerosols directly scatter and absorb radiation. The scattering of radiation causes atmospheric cooling, whereas absorption can cause atmospheric warming. Source: © Taro Tayler. You may also be interested in. Discovering Geology. Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages. Show more Climate change. Climate is the pattern of weather of an area averaged over many years. We can only show whether climate change has occurred after decades of careful measurements and analysis. Show more What causes the Earth’s climate to change? Geological records demonstrate that there have been a number of large variations in Earth’s climate in the past. Show more Impacts of climate change. Temperature rises can affect agriculture, sea levels and the frequency of extreme weather incidents. We can study past climate change by looking at the evidence in rocks, fossils and changes in the landscape. Show more The carbon story. The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere into the Earth, then released back into the atmosphere. Show more Understanding carbon capture and storage. Carbon capture and storage involves capturing carbon dioxide at emission sources, such as power stations, then transporting and storing it underground. Show more What are we doing about climate change? BGS is committed to research aimed at slowing down the effects of a changing climate, whilst helping society to become resilient to climate change. Show more Footnotes. 1. Enhanced Greenhouse effect 'Greenhouse gases' are actually crucial to keeping our planet at a habitable temperature, without them the Earth would be about minus 17 degrees! Anthropogenic or human release of carbon dioxide is what is contributing to an additional or enhanced greenhouse effect. Footnote Definition Was this page helpful? Yes No Close Button
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                            [body] => Causes of climate change The evidence is clear: the main cause of climate change is burning fossil fuels such as oil, gas, and coal. When burnt, fossil fuels release carbon dioxide into the air, causing the planet to heat up. What causes climate change? The climate on Earth has been changing since it formed 4.5 billion years ago. Until recently, natural factors have been the cause of these changes. Natural influences on the climate include volcanic eruptions, changes in the orbit of the Earth, and shifts in the Earth's crust (known as plate tectonics). Over the past one million years, the Earth has experienced a series of ice ages, including cooler periods (glacials) and warmer periods (interglacials). Glacial and interglacial periods cycle roughly every 100,000 years, caused by changes in Earth's orbit around the sun. For the past few thousand years, Earth has been in an interglacial period with a constant temperature. However, since the Industrial Revolution in the 1800s, the global temperature has increased at a much faster rate. By burning fossil fuels and changing how we use the land, human activity has quickly become the leading cause of changes to our climate. How does the climate system work? Greenhouse gases and the greenhouse effect. Some gases in the Earth's atmosphere trap heat and stop it escaping into space. We call these 'greenhouse gases'. These gases act as a warming blanket around the Earth, known as the 'greenhouse effect'. Greenhouse gases come from both human and natural sources. Gases like carbon dioxide, methane, and nitrous oxide naturally occur in the atmosphere. Others, such as chlorofluorocarbons (CFCs), are only produced by human activity. When short-wave radiation from the sun reaches Earth, most of it passes straight through and hits the surface. The Earth absorbs most of this radiation and gives off longer-wavelength infrared radiation. The greenhouse gases absorb some of this infrared radiation, instead of it passing straight out into space. The atmosphere then emits radiation in all directions, sending some of it back to the surface, causing the planet to heat up. This process is known as the 'greenhouse effect'. The greenhouse effect is critical to our survival. In fact, without greenhouse gases, Earth would be about 30 degrees colder than it is today. Without greenhouse gases and their warming effect, we wouldn't be able to survive. However, since the Industrial Revolution, we've been adding more and more greenhouse gases into the air, trapping even more heat. Instead of keeping Earth at a warm, stable temperature, the greenhouse effect is heating the planet at a much faster rate. We call this the 'enhanced greenhouse effect' and it's the main cause of climate change. Human causes of climate change. Humans cause climate change by releasing carbon dioxide and other greenhouse gases into the air. Today, there is more carbon dioxide in the atmosphere than there ever has been in at least the past 2 million years. During the 20th and 21st century, the level of carbon dioxide rose by 40%. We produce greenhouse gases in lots of different ways: Burning fossil fuels – Fossil fuels such as oil, gas, and coal contain carbon dioxide that has been 'locked away' in the ground for thousands of years. When we take these out of the land and burn them, we release the stored carbon dioxide into the air. Deforestation – Forests remove and store carbon dioxide from the atmosphere. Cutting them down means that carbon dioxide builds up quicker since there are no trees to absorb it. Not only that, trees release the carbon they stored when we burn them. Agriculture – Planting crops and rearing animals releases many different types of greenhouse gases into the air. For example, animals produce methane, which is 30 times more powerful than carbon dioxide as a greenhouse gas. The nitrous oxide used for fertilisers is ten times worse and is nearly 300 times more potent than carbon dioxide! Cement – Producing cement is another contributor to climate change, causing 2% of our entire carbon dioxide emissions. Natural changes to the climate. The leading cause of climate change is human activity and the release of greenhouse gases. However, there are lots of natural causes that also lead to changes in the climate system. Natural cycles can cause the climate to alternate between warming and cooling. There are also natural factors that force the climate to change, known as 'forcings'. Even though these natural causes contribute to climate change, we know that they are not the primary cause, based on scientific evidence. Some of these natural cycles include: Milankovitch cycles – As Earth travels around the sun, its path and the tilt of its axis can change slightly. These changes, called Milankovitch cycles, affect the amount of sunlight that falls on Earth. This can cause the temperature of Earth to change. However, these cycles take place over tens or hundreds of thousands of years and are unlikely to be causing the changes to the climate that we are seeing today. El Niño Southern Oscillation (ENSO) – ENSO is a pattern of changing water temperatures in the Pacific Ocean. In an 'El Niño' year, the global temperature warms up, and in a 'La Niña' year, it cools down. These patterns can affect the global temperature for a short amount of time (months or years) but cannot explain the persistent warming that we see today. What is El Niño, what does it mean and how does it affect weather around the world? Natural forcings that can contribute to climate change include: Solar irradiance – Changing energy from the sun has affected the temperature of Earth in the past. However, we have not seen anything strong enough to change our climate. Any increase in solar energy would make the entire atmosphere of Earth warm, but we can only see warming in the bottom layer. Volcanic eruptions – Volcanoes have a mixed effect on our climate. Eruptions produce aerosol particles that cool Earth, but they also release carbon dioxide, which warms it. Volcanoes produce 50 times less carbon dioxide than humans do, so we know they are not the leading cause of global warming. On top of this, cooling is the dominant effect of volcanic eruptions, not warming. Are humans responsible for climate change? When looking at all the evidence, there is a large scientific consensus that humans are the leading cause of climate change. In their latest report, the Intergovernmental Panel on Climate Change stated unequivocally that human activity is the cause of global warming. Natural climate cycles can change the temperature of Earth, but the changes we are seeing are happening at a scale and speed that natural cycles cannot explain. These cycles affect the global temperature for years, or sometimes just months, not the 100 years that we have observed. Meanwhile, longer-term changes like Milankovitch cycles and solar irradiance take thousands and thousands of years. There are lots of things that affect climate change, but the evidence is irrefutable. Human activity, such as burning fossil fuels and changing how we use the land, is the leading cause of climate change. Related links. What is climate change? Effects of climate change Climate change questions UK climate Climate science Organisations and reports Help us improve our website. Take our short survey
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                            [body] => Greenhouse gases: Causes, sources and environmental effects By Tiffany Means , Marc Lallanilla published 9 June 21 Greenhouse gases help keep the Earth at a habitable temperature — until there is too much of them. Greenhouse gases are being emitted into the atmosphere with dire consequences. Here, a factory emits a harmful gas. (Image credit: Tatiana Grozetskaya/Shutterstock.com) Jump to: Solar radiation and the "greenhouse effect" Global warming Sources Future outlook Additional resources Behind the phenomena of global warming and climate change lies the increase in greenhouse gases in our atmosphere. A greenhouse gas is any gaseous compound in the atmosphere that is capable of absorbing infrared radiation, thereby trapping and holding heat in the atmosphere. By increasing the heat in the atmosphere, greenhouse gases are responsible for the greenhouse effect, which ultimately leads to global warming.Related: 10 signs that Earth's climate is off the railsSolar radiation and the "greenhouse effect". Global warming isn't a recent scientific concept. The basics of the phenomenon were worked out well over a century ago by Swedish physicist and chemist Svante Arrhenius, in 1896. His paper, published in the Philosophical Magazine and Journal of Science, was the first to quantify the contribution of carbon dioxide to what scientists now call the "greenhouse effect."The greenhouse effect occurs because the sun bombards Earth with enormous amounts of radiation that strike Earth's atmosphere in the form of visible light, plus ultraviolet (UV), infrared (IR) and other types of radiation that are invisible to the human eye. UV radiation has a shorter wavelength and a higher energy level than visible light, while IR radiation has a longer wavelength and a weaker energy level. About 30% of the radiation that strikes Earth is reflected back out to space by clouds, ice and other reflective surfaces. The remaining 70% is absorbed by the oceans, the land and the atmosphere, according to NASA's Earth Observatory.As they heat up, the oceans, land and atmosphere release heat in the form of IR thermal radiation, which passes out of the atmosphere and into space. It's this equilibrium of incoming and outgoing radiation that makes the Earth habitable, with an average temperature of about 59 degrees Fahrenheit (15 degrees Celsius), according to NASA. Without this atmospheric equilibrium, Earth would be as cold and lifeless as its moon, or as blazing hot as Venus. The moon, which has almost no atmosphere, is about minus 243 F (minus 153 C) on its dark side. Venus, on the other hand, has a very dense atmosphere that traps solar radiation; the average temperature on Venus is about 864 F (462 C).The exchange of incoming and outgoing radiation that warms the Earth is often referred to as the greenhouse effect because an agricultural greenhouse works in much the same way. Incoming shortwave UV radiation easily passes through the glass walls of a greenhouse and is absorbed by the plants and hard surfaces inside. Weaker, longwave IR radiation, however, has difficulty passing through the glass walls and is thereby trapped inside, warming the greenhouse.How greenhouse gases cause global warming. The gases in the atmosphere that absorb radiation are known as "greenhouse gases" (abbreviated as GHG) because they are largely responsible for the greenhouse effect. The greenhouse effect, in turn, is one of the leading causes of global warming. The most significant greenhouse gases, according to the Environmental Protection Agency (EPA), are: water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). "While oxygen (O2) is the second most abundant gas in our atmosphere, O2 does not absorb thermal infrared radiation," Michael Daley, an associate professor of environmental science at Lasell College in Massachusetts, told Live Science.Global warming and the greenhouse gases that cause it occur naturally — without them, Earth's average surface temperature would be a gelid zero degrees F (minus 18 C). But the amount of greenhouse gases in the atmosphere has skyrocketed to detrimental levels in recent history. Related: Carbon dioxide soars to record breaking levels not seen in at least 800,000 yearsDuring the 20,000-year period before the Industrial Revolution, atmospheric CO2 fluctuated between about 180 parts per million (ppm) during ice ages and 280 ppm during interglacial warm periods. However, since the beginning of the Industrial Revolution in the 1750s, the amount of CO2 has risen nearly 50%, according to NASA’s Global Climate Change portal. Today, CO2 levels stand at over 410 ppm.Fluorinated gases — gases to which the element fluorine has been added — are created during industrial processes and are also considered greenhouse gases. These include hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. Although they are present in the atmosphere in very small concentrations, they trap heat very effectively, making them high "global warming potential" (GWP) gases.Chlorofluorocarbons (CFCs), once used as refrigerants and aerosol propellants until they were phased out by international agreement, are also greenhouse gases.Related: Global warming vs. solar cooling: The showdown begins in 2020There are three factors that affect the degree to which a greenhouse gas will influence global warming: Its abundance in the atmosphere, how long it stays in the atmosphere and its GWP. For example, water vapor is the most abundant greenhouse gas, but carbon dioxide has a more significant impact on global warming due to its abundance in the atmosphere plus its relatively long atmospheric lifetime of 300 to 1,000 years, according to NASA. Water vapor, on the other hand, has an atmospheric lifetime of no more than 10 days, according to a 2020 study published in the Journal of the Atmospheric Sciences.Methane is about 21 times more efficient at absorbing radiation than CO2, giving it a higher GWP rating, even though it stays in the atmosphere for only about 12 years, according to the United Nations Framework Convention on Climate Change (UNFCCC). Although methane and other GHGs are capable of trapping more heat than CO2, scientists still consider carbon dioxide to be the dominant greenhouse gas because its warming effect outlives the others' effects by centuries.Sources of greenhouse gases. Some greenhouse gases, such as methane, are produced through agricultural practices, in the form of livestock manure, for example. Others, like CO2, largely result from natural processes like respiration, and from the burning of fossil fuels like coal, oil and gas.Another primary source of CO2 is deforestation. When trees are felled to produce goods or heat, they release the carbon that is normally stored for photosynthesis. This process releases up to 4.8 billion metric tons of carbon into the atmosphere every year, according to the World Resources Institute.Forestry and other land-use practices can offset some of these greenhouse gas emissions. "Replanting helps to reduce the buildup of carbon dioxide in the atmosphere as growing trees sequester carbon dioxide through photosynthesis," Daley told Live Science. "However, forests cannot sequester all of the carbon dioxide we are emitting to the atmosphere through the burning of fossil fuels, and a reduction in fossil fuel emissions is still necessary to avoid buildup in the atmosphere."Worldwide, the output of greenhouse gases is a source of grave concern. According to NOAA’s Climate.gov, over the past 60 years, atmospheric CO2 has increased at an annual rate that's 100 times faster than previous natural increases. The last time global atmospheric CO2 amounts were this high was 3 million years ago, when temperatures were up to 5.4 degrees F (3 degrees C) higher than during the pre-industrial era. As a result of modern-day CO2-induced global warming, 2016 was the warmest year on record, with 2019 and 2020 ranking as the next warmest, respectively. In fact, the six hottest years on record have all occurred since 2015, according to the World Meteorological Organization."The warming we observe affects atmospheric circulation, which impacts rainfall patterns globally," said Josef Werne, an associate professor in the Department of Geology and Planetary Science at the University of Pittsburgh. "This will lead to big environmental changes, and challenges, for people all across the globe."Our planet's future. If current trends continue, scientists, government officials and a growing number of citizens fear that the worst effects of global warming — extreme weather, rising sea levels, plant and animal extinctions, ocean acidification, major shifts in climate and unprecedented social upheaval — will be inevitable.In an effort to combat GHG-induced global warming, the U.S. government created a climate action plan in 2013. And in April 2016, representatives from 73 countries signed the Paris Agreement, an international pact to combat climate change by investing in a sustainable, low-carbon future, according to the UNFCCC. Although the U.S. withdrew from the Paris Agreement in 2017, it rejoined in late-January 2021. President Biden's administration has also set a target of reducing U.S. emissions by 50-52% of 2005 levels by the year 2030. (Emissions are routinely compared to those in 2005 — the year U.S. emissions of CO2 peaked at nearly 6 billion tons.)In 2020, global carbon dioxide emissions fell 6.4% (13% in the U.S. alone) — the first time in decades the annual rate hasn’t climbed, Nature reported. This was in part due to the decrease in fossil fuel combustion resulting from the switch to natural gas from coal, but largely because of the forced standstill in economic, social and transportation activities in response to the COVID-19 pandemic. Scientists expected the annual emissions decline to actually be larger than it was, but emissions rebounded as restrictions were lifted in some nations and activities recovered toward the end of 2020. Related: Global carbon emissions dropped an unprecedented 17% during the coronavirus lockdown — and it changes nothingIn order to limit global warming to the 2.7 degree F (1.5 degree C) target set by the Paris Agreement, the world still needs to cut its CO2 emissions by 7.6% for the next decade, according to the UN Environment Programme. Researchers around the world continue to work toward finding ways to lower greenhouse gas emissions and mitigate their effects. One potential solution scientists are examining is to suck some of the carbon dioxide out of the atmosphere and bury it underground indefinitely. Advocates argue that carbon capture and storage is technologically feasible, but market forces have prevented widespread adoption. Whether or not removing already-emitted carbon from the atmosphere is feasible, preventing future warming requires stopping the emissions of greenhouse gases. The most ambitious effort to forestall warming thus far is the 2016 Paris Agreement. This nonbinding international treaty aims to keep warming "well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius," according to the United Nations. Each signatory to the treaty agreed to set their own voluntary greenhouse gas emission limits and to make them stricter over time. Climate scientists said that the emissions limits committed under the agreement wouldn't keep warming as low as 1.5 or even 2 degrees C, but that it would be an improvement over the "business-as-usual" scenario.Additional resources. Find out the latest research and policy updates regarding global warming via NOAA's Climate.gov portal.Learn more about the Global Carbon Project.Read more about the impact of COVID-19 on 2020 CO2 emissions, according to Carbon Brief. Tiffany Means Tiffany Means is a meteorologist turned science writer based in the Blue Ridge mountains of North Carolina. Her work has appeared in Yale Climate Connections, The Farmers' Almanac, and other publications. Tiffany has a bachelor's degree in atmospheric science from the University of North Carolina, Asheville, and she is earning a master's in science writing at Johns Hopkins University. 
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                            [body] => Energy and the environment explained Greenhouse gases and the climate Basics +Menu What is energy? Units and calculators U.S. energy facts Use of energy Energy and the environment Close Also in What is energy? What is energy? Forms of energy Sources of energy Laws of energy Close Also in Units and calculators explained. Units and calculators Energy conversion calculators British thermal units (Btu) Degree days Close Also in U.S. energy facts explained. U.S. energy facts State and U.S. territory data Close Also in Use of energy explained. Use of energy Energy use in industry Energy use for transportation Energy use in homes Energy use in commercial buildings Energy efficiency and conservation Close Also in Energy and the environment explained. Energy and the environment Greenhouse gases Greenhouse gases and the climate Where greenhouse gases come from Outlook for future emissions Recycling and energy Nonrenewable sources Oil and petroleum products Gasoline Diesel fuel Heating oil Close Also in Oil and petroleum products explained. Oil and petroleum products Refining crude oil Where our oil comes from Imports and exports Offshore oil and gas Use of oil Prices and outlook Oil and the environment Close Also in Gasoline explained. Gasoline Octane in depth Where our gasoline comes from Use of gasoline Prices and outlook Factors affecting gasoline prices Regional price differences Price fluctuations History of gasoline Gasoline and the environment Close Also in Diesel fuel explained. Diesel fuel Where our diesel comes from Use of diesel Prices and outlook Factors affecting diesel prices Diesel fuel surcharges Diesel and the environment Close Also in Heating oil explained. Heating oil Where our heating oil comes from Use of heating oil Prices and outlook Factors affecting heating oil prices Hydrocarbon Gas Liquids Natural gas Coal Nuclear Close Also in Hydrocarbon gas liquids explained. Hydrocarbon gas liquids Where do hydrocarbon gas liquids come from? Transporting and storing Uses of hydrocarbon gas liquids Imports and exports Prices Close Also in Natural gas explained. Natural gas Delivery and storage Natural gas pipelines Liquefied natural gas Where our natural gas comes from Imports and exports How much gas is left Use of natural gas Prices Factors affecting natural gas prices Natural gas and the environment Customer choice programs Close Also in Coal explained. Coal Mining and transportation Where our coal comes from Imports and exports How much coal is left Use of coal Prices and outlook Coal and the environment Close Also in Nuclear explained. Nuclear Nuclear power plants The nuclear fuel cycle Where our uranium comes from U.S. nuclear industry Nuclear power and the environment Renewable sources Renewable energy Hydropower Biomass Biofuels: Ethanol and Biomass-based diesel Close Also in Renewable energy explained. Renewable energy Types & usages Incentives Portfolio standards Close Also in Hydropower explained. Hydropower Where hydropower is generated Hydropower and the environment Tidal power Wave power Ocean thermal energy conversion Close Also in Biomass explained. Biomass Wood and wood waste Waste-to-energy (MSW) Landfill gas and biogas Biomass and the environment Close Also in Biofuels explained. Biofuels Ethanol Use and supply of ethanol Ethanol and the environment Biomass-based diesel fuels Use of biomass-based diesel fuel Biomass-based diesel and the environment Wind Geothermal Solar Close Also in Wind explained. Wind Electricity generation from wind Where wind power is harnessed Types of wind turbines History of wind power Wind energy and the environment Close Also in Geothermal explained. Geothermal Where geothermal energy is found Use of geothermal energy Geothermal power plants Geothermal heat pumps Geothermal energy and the environment Close Also in Solar explained. Solar Photovoltaics and electricity Where solar is found and used Solar thermal power plants Solar thermal collectors Solar energy and the environment Secondary sources Electricity Hydrogen Close Also in Electricity explained. Electricity The science of electricity Magnets and electricity Batteries, circuits, and transformers Measuring electricity How electricity is generated Electricity in the United States Generation, capacity, and sales Delivery to consumers Use of electricity Prices and factors affecting prices Electricity and the environment Close Also in Hydrogen explained. Hydrogen Production of hydrogen Use of hydrogen Greenhouse gas emissions and atmospheric concentrations have increased over the past 150 years. Emissions of several important greenhouse gases that result from human activity have increased substantially since large-scale industrialization began in the mid-1800s. Most of these human-caused (anthropogenic) greenhouse gas emissions were carbon dioxide (CO2) from burning fossil fuels. Concentrations of CO2 in the atmosphere are naturally regulated by many processes that are part of the global carbon cycle. The flux, or movement, of carbon between the atmosphere and the earth's land and oceans is dominated by natural processes like plant photosynthesis. Although these natural processes can absorb some of the anthropogenic CO2 emissions produced each year (measured in carbon equivalent terms), starting in about 1950, CO2 emissions began exceeding the capacity of these processes to absorb carbon. This imbalance between greenhouse gas emissions and the ability for natural processes to absorb those emissions has resulted in a continued increase in atmospheric concentrations of greenhouse gases. Concentrations of CO2 in the atmosphere have increased by about 43% since 1850. Click to enlarge Greenhouse gases warm the planet. Scientists know with virtual certainty that increasing greenhouse gas concentrations tend to warm the planet. In computer-based models, rising concentrations of greenhouse gases produce an increase in the average surface temperature of the earth over time. Rising temperatures may produce changes in precipitation patterns, storm severity, and sea level. Collectively, this is commonly referred to as climate change. Assessments by the Intergovernmental Panel on Climate Change (IPCC) suggest that the earth’s climate warmed 0.85 degrees Centigrade (1.53 degrees Fahrenheit) between 1880 and 2012 and that human activity affecting the atmosphere is likely an important driving factor. The IPCC’s Fifth Assessment Report (Summary for Policymakers) states, "Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century." did youknow? In 2019, fossil fuels were the source of about 80% of U.S. primary energy consumption, 94% of total U.S. carbon dioxide emissions, and 80% of total U.S. greenhouse gas emissions resulting from human activity. The report later states, "It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together." The report also states, "Concentrations of CO2, CH4, and N2O now substantially exceed the highest concentrations recorded in ice cores during the past 800,000 years. The mean rates of increase in atmospheric concentrations over the past century are, with very high confidence, unprecedented in the last 22,000 years." Last updated: December 8, 2021 Also in Energy and the environment explained. Energy and the environment Greenhouse gases Greenhouse gases and the climate Where greenhouse gases come from Outlook for future emissions Recycling and energy Learn more. International Energy Statistics, World Carbon Dioxide Emissions Carbon Dioxide Information Analysis Center Atmospheric carbon dioxide concentrations data Global CO2 Emissions from Fossil-Fuel Burning, Cement Manufacture, and Gas Flaring: 1751-2014 Carbon dioxide emissions from U.S. energy consumption Greenhouse Gas (GHG) Emissions Overview of Greenhouse Gases Articles on greenhouse gases Also on Energy Explained. U.S. energy facts Use of coal Use of natural gas Use of oil Frequently asked questions. What are the energy-related carbon dioxide emissions by source and sector for the United States? How much carbon dioxide is produced when different fuels are burned? What are the sources of energy-related carbon dioxide emissions by type of fuel for the United States and the world?
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                            [title] => Climate change: evidence and causes | Royal Society
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                            [title] => Frontiers | Climate Change and the Impact of Greenhouse Gasses: CO2 and NO, Friends and Foes of Plant Oxidative Stress | Plant Science
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                            [description] => Here, we review information on how plants face redox imbalance caused by climate change, and focus on the role of nitric oxide (NO) in this response. Life on Earth is possible thanks to greenhouse effect. Without it, temperature on Earth's surface would be around −19°C, instead of the current average of 14°C. Greenhouse effect is produced by greenhouse gases (GHG) like water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxides (NxO) and ozone (O3). GHG have natural and anthropogenic origin. However, increasing GHG provokes extreme climate changes such as floods, droughts and heat, which induce reactive oxygen species (ROS) and oxidative stress in plants. The main sources of ROS in stress conditions are: augmented photorespiration, NADPH oxidase (NOX) activity, β-oxidation of fatty acids and disorders in the electron transport chains of mitochondria and chloroplasts. Plants have developed an antioxidant machinery that includes the activity of ROS detoxifying enzymes [e.g. superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX), and peroxiredoxin (PRX)], as well as antioxidant molecules such as ascorbic acid (ASC) and glutathione (GSH) that are present in almost all subcellular compartments. CO2 and NO help to maintain the redox equilibrium. Higher CO2 concentrations increase the photosynthesis through the CO2-unsaturated Rubisco activity. But Rubisco photorespiration and NOX activities could also augment ROS production. NO regulate the ROS concentration preserving balance among ROS, GSH, GSNO and ASC. When ROS are in huge concentration, NO induces transcription and activity of SOD, APX, and CAT. However, when ROS are necessary (e.g. for pathogen resistance), NO may inhibit APX, CAT and NOX activity by the S-nitrosylation of cysteine residues, favoring cell death. NO also regulates GSH concentration in several ways. NO may react with GSH to form GSNO, the NO cell reservoir and main source of S-nitrosylation. GSNO could be decomposed by the GSNO reductase (GSNOR) to GSSG which, in turn, is reduced to GSH by glutathione reductase (GR). GSNOR may be also inhibited by S-nitrosylation and GR activated by NO. In conclusion, NO plays a central role in the tolerance of plants to climate change
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Is+nitric+oxide+toxic+or+protective%B4&journal=Trends+Plant+Sci%2E&author=Beligni+M.+V.&author=and+Lamattina+L.&publication_year=1999a&volume=4&pages=299-300
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+protects+against+cellular+damage+produced+by+methylviologen+herbicides+in+potato+plants%2E&journal=Nitric+Oxide&author=Beligni+M.+V.&author=and+Lamattina+L.&publication_year=1999b&volume=3&pages=199-208
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Europe-wide+reduction+in+primary+productivity+caused+by+the+heat+and+drought+in+2003%2E&journal=Nature&author=Ciais+P.&author=Reichstein+M.&author=Viovy+N.&author=Granier+A.&author=Ogée+J.&author=Allard+V.&publication_year=2005&volume=437&pages=529-533
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+inhibition+of+tobacco+catalase+and+ascorbate+peroxidase%2E&journal=Mol%2E+Plant%2E+Microbe%2E++Interact%2E&author=Clark+D.&author=Durner+J.&author=Navarre+D.+A.&author=and+Klessig+D.+F.&publication_year=2000&volume=13&pages=1380-1384
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Will+plant+movements+keep+up+with+climate+change%B4&journal=Trends+Ecol%2E+Evol%2E&author=Corlett+R.+T.&author=and+Westcott+D.+A.&publication_year=2013&volume=28&pages=482-488
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Current+overview+of+S-nitrosoglutathione+%28GSNO%29+in+higher+plants%2E&journal=Front%2E+Plant+Sci%2E&author=Corpas+F.+J.&author=Alché+J.+D.&author=and+Barroso+J.+B.&publication_year=2013
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Auxin+induces+redox+regulation+of+ascorbate+peroxidase+1+activity+by+S-nitrosylation%2Fdenitrosylation+balance+resulting+in+changes+of+root+growth+pattern+in+Arabidopsis%2E&journal=J%2E+Exp%2E+Bot%2E&author=Correa-Aragunde+N.&author=Foresi+N.&author=Delledonne+M.&author=and+Lamattina+L.&publication_year=2013&volume=64&pages=3339-3349
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+is+a+ubiquitous+signal+for+maintaining+redox+balance+in+plant+cells%3A+regulation+of+ascorbate+peroxidase+as+a+case+study%2E&journal=J%2E++Exp%2E++Bot%2E&author=Correa-Aragunde+N.&author=Foresi+N.&author=and+Lamattina+L.&publication_year=2015&volume=66&pages=2913-2921
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Ascorbate+and+glutathione%3A+the+heart+of+the+redox+hub%2E&journal=Plant+Physiol%2E&author=Foyer+C.+H.&author=and+Noctor+G.&publication_year=2011&volume=155&pages=2-18
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                                                )

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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Ultraviolet-B-radiation-mediated+responses+in+plants%2E++Balancing+damage+and+protection%2E&journal=Plant+Physiol%2E&author=Frohnmeyer+H.&author=and+Staiger+D.&publication_year=2003&volume=133&pages=1420-1428
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+regulates+K%2B+and+Cl-channels+in+guard+cells+through+a+subset+of+abscisic+acid-evoked+signaling+pathways%2E&journal=Proc%2E+Natl%2E+Acad%2E++Sci%2E+U%2ES%2EA%2E&author=García-Mata+C.&author=Gay+R.&author=Sokolovski+S.&author=Hills+A.&author=Lamattina+L.&author=and+Blatt+M.+R.&publication_year=2003&volume=100&pages=11116-11121
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                                                )

                                            [109] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Gasotransmitters+are+emerging+as+new+guard+cell+signaling+molecules+and+regulators+of+leaf+gas+exchange%2E&journal=Plant+Sci%2E&author=García-Mata+C.&author=and+Lamattina+L.&publication_year=2013&volume=202&pages=66-73
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Urbanization+effects+on+tree+growth+in+the+vicinity+of+New+York+City%2E&journal=Nature&author=Gregg+J.&author=Jones+C.&author=and+Dawson+T.&publication_year=2003&volume=424&pages=183-187
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Phytochelatins%2C+the+heavy-metal-binding+peptides+of+plants%2C+are+synthesized+from+glutathione+by+a+specific+gamma-glutamylcysteine+dipeptidyl+transpeptidase+%28phytochelatin+synthase%29%2E&journal=Proc%2E+Natl%2E+Acad%2E+Sci%2E+U%2ES%2EA%2E&author=Grill+E.&author=Löffler+S.&author=Winnacker+E.+L.&author=and+Zenk+M.+H.&publication_year=1989&volume=86&pages=6838-6842
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Reactive+nitrogen+species+in+mitochondria+and+their+implications+in+plant+energy+status+and+hypoxic+stress+tolerance%2E&journal=Front%2E+Plant+Sci%2E&author=Gupta+K.+J.&author=and+Igamberdiev+A.+U.&publication_year=2016
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                                            [120] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Soil+N2O+and+NO+emissions+from+an+arid%2C+urban+ecosystem%2E&journal=J%2E+Geophys%2E+Res%2E&author=Hall+S.&author=Huber+D.&author=and+Grimm+N.&publication_year=2008
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                                            [123] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Physiological%2C+biochemical%2C+and+molecular+mechanisms+of+heat+stress+tolerance+in+plants%2E&journal=Int%2E+J%2E+Mol%2E+Sci%2E&author=Hasanuzzaman+M.&author=Nahar+K.&author=Alam+M.+M.&author=Roychowdhury+R.&author=and+Fujita+M.&publication_year=2013&volume=14&pages=9643-9684
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Differential+inhibition+of+Arabidopsis+superoxide+dismutases+by+peroxynitrite-mediated+tyrosine+nitration%2E&journal=J%2E+Exp%2E+Bot%2E&author=Holzmeister+C.&author=Gaupels+F.&author=Geerlof+A.&author=Sarioglu+H.&author=Sattler+M.&author=Durner+J.&publication_year=2015&volume=66&pages=989-999
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Climate+Change+2014%3A+Mitigation+of+Climate+Change%2E++Contribution+of+Working+Group+III+to+the+Fifth+Assessment+Report+of+the+Intergovernmental+Panel+on+Climate+Change&publication_year=2014
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Elevated+carbon+dioxide+improves+plants+iron+nutrition+through+enhancing+the+iron-deficiency-induced+responses+under+iron-limited+conditions+in+tomato%2E&journal=Plant+Physiol%2E&author=Jin+C.+W.&author=Du+S.+T.&author=Chen+W.+W.&author=Li+G.+X.&author=Zhang+Y.+S.&author=and+Zheng+S.+J.&publication_year=2009&volume=150&pages=272-280
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Modern+global+climate+change%2E&journal=Science&author=Karl+T.+R.&author=and+Trenberth+K.+E.&publication_year=2003&volume=302&pages=1719-1723
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+in+marine+photosynthetic+organisms%2E&journal=Nitric+Oxide&author=Kumar+A.&author=Castellano+I.&author=Patti+F.+P.&author=Palumbo+A.&author=and+Buia+M.+C.&publication_year=2015&volume=47&pages=34-39
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=%22Historical+overview+of+climate+change+science%2C%22+in&journal=Climate++change+2007%3A+The+physical+science+basis%2E+Contribution+of+Working+Group+I+to+the+Fourth+Assessment+Report+of+the+Intergovernmental+Panel+on+Climate+Change&author=Le+Treut+H.&author=Somerville+R.&author=Cubasch+U.&author=Ding+Y.&author=Mauritzen+C.&author=Mokssit+A.&publication_year=2007
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=NO+signals+in+the+haze%3A+nitric+oxide+signalling+in+plant+defence%2E&journal=Curr%2E+Opin%2E++Plant+Biol%2E&author=Leitner+M.&author=Vandelle+E.&author=Gaupels+F.&author=Bellin+D.&author=and+Delledonne+M.&publication_year=2009&volume=12&pages=451-458
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Food+for+thought%3A+lower-than-expected+crop+yield+stimulation+with+rising+CO2+concentrations%2E&journal=Science&author=Long+S.&author=Ainsworth+E.&author=Leakey+A.&author=Nösberger+J.&author=and+Ort+D.&publication_year=2006&volume=312&pages=1918-1921
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Abscisic+acid+improves+drought+tolerance+of+triploid+bermudagrass+and+involves+H2O2-+and+NO-induced+antioxidant+enzyme+activities%2E&journal=Plant+Physiol%2E++Biochem%2E&author=Lu+S.&author=Su+W.&author=Li+H.&author=and+Guo+Z.&publication_year=2009&volume=7&pages=132-138
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=A+burst+of+plant+NADPH+oxidases%2E&journal=Trends+Plant+Sci%2E&author=Marino+D.&author=Dunand+C.&author=Puppo+A.&author=and+Pauly+N.&publication_year=2012&volume=17&pages=9-15
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Transcriptional+reprogramming+and+stimulation+of+leaf+respiration+by+elevated+CO2+concentration+is+diminished%2C+but+not+eliminated%2C+under+limiting+nitrogen+supply%2E&journal=Plant+Cell+Environ%2E&author=Markelz+R.++J.&author=Lai+L.++X.&author=Vosseler+L.++N.&author=and+Leakey+A.++D.&publication_year=2014&volume=37&pages=886-988
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Does+ozone+increase+ABA+levels+by+non-enzymatic+synthesis+causing+stomata+to+close%B4&journal=Plant+Cell+Environ%2E&author=McAdam+E.+L.&author=Brodribb+T.+J.&author=and+McAdam+S.+A.&publication_year=2017&volume=40&pages=741-747
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=A+review+of+soil+NO+transformation%3A+associated+processes+and+possible+physiological+significance+on+organisms%2E&journal=Soil+Biol%2E+Biochem%2E&author=Medinets+S.&author=Skiba+U.&author=Rennenberg+H.&author=and+Butterbach-Bahl+K.&publication_year=2015&volume=80&pages=92-117
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Is+nitrate+reductase+a+major+player+in+the+plant+NO+%28nitric+oxide%29+game%B4&journal=Photosynth%2E+Res%2E&author=Meyer+C.&author=Lea+U.++S.&author=Provan+F.&author=Kaiser+W.++M.&author=and+Lillo+C.&publication_year=2005&volume=83&pages=181-189
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Regulation+of+nitric+oxide+%28NO%29+production+by+plant+nitrate+reductase+in+vivo+and+in+vitro%2E&journal=J%2E+Exp%2E+Bot%2E&author=Rockel+P.&author=Strube+F.&author=Rockel+A.&author=Wildt+J.&author=and+Kaiser+W.+M.&publication_year=2002&volume=53&pages=103-110
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Anion+channels%3A+master+switches+of+stress+responses%2E&journal=Trends+Plant+Sci%2E&author=Roelfsema+M.++R.&author=Hedrich+R.&author=and+Geiger+D.&publication_year=2012&volume=17&pages=221-229
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                                            [217] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Proteomic+analysis+of+S-nitrosylated+proteins+in+Arabidopsis+thaliana+undergoing+hypersensitive+response%2E&journal=Proteomics&author=Romero-Puertas+M.++C.&author=Campostrini+N.&author=Mattè+A.&author=Righetti+P.++G.&author=Perazzolli+M.&author=Zolla+L.&publication_year=2008&volume=8&pages=1459-1469
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                                                )

                                            [220] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=S-nitrosylation+of+peroxiredoxin+II+E+promotes+peroxynitrite-mediated+tyrosine+nitration%2E&journal=Plant+Cell&author=Romero-Puertas+M.+C.&author=Laxa+M.&author=Mattè+A.&author=Zaninotto+F.&author=Finkemeier+I.&author=Jones+A.++M.++E.&publication_year=2007&volume=19&pages=4120-4130
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                                                )

                                            [223] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=The+role+of+glutathione+in+photosynthetic+organisms%3A+emerging+functions+for+glutaredoxins+and+glutathionylation%2E&journal=Annu%2E+Rev%2E+Plant+Biol%2E&author=Rouhier+N.&author=Lemaire+S.++D.&author=and+Jacquot+J.-P.&publication_year=2008&volume=59&pages=143-166
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+induces+specific+isoforms+of+antioxidant+enzymes+in+soybean+leaves+subjected+to+enhanced+ultraviolet-B+radiation%2E&journal=J%2E++Photochem%2E+Photobiol%2E+B&author=Santa-Cruz+D.&author=Pacienza+N.&author=Zilli+C.&author=Tomaro+M.&author=Balestrasse+K.&author=and+Yannarelli+G.&publication_year=2014&volume=141&pages=202-209
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=The+broad+footprint+of+climate+change+from+genes+to+biomes+to+people%2E&journal=Science&author=Scheffers+B.+R.&author=De+Meester+L.&author=Bridge+T.+C.&author=Hoffmann+A.+A.&author=Pandolfi+J.++M.&author=Corlett+R.+T.&publication_year=2016
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                                            [231] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Attribution+of+the+present-day+total+greenhouse+effect%2E&journal=J%2E++Geophys%2E++Res%2E&author=Schmidt+G.++A.&author=Ruedy+R.++A.&author=Miller+R.++L.&author=and+Lacis+A.++A.&publication_year=2010
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                                            [234] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Guard+cell+hydrogen+peroxide+and+nitric+oxide+mediate+elevated+CO2-induced+stomatali+movement+in+tomato%2E&journal=New+Phytol%2E&author=Shi+K.&author=Li+X.&author=Zhang+H.&author=Zhang+G.&author=Liu+Y.&author=Zhou+Y.&publication_year=2015&volume=208&pages=342-353
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                                                )

                                            [237] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Exogenous+nitric+oxide+protect+cucumber+roots+against+oxidative+stress+induced+by+salt+stress%2E&journal=Plant+Physiol%2E+Biochem%2E&author=Shi+Q.&author=Ding+F.&author=Wang+X.&author=and+Wei+M.&publication_year=2007&volume=45&pages=542-550
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                                                    [isOutbound] => 1
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                                                )

                                            [240] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Protective+effect+of+nitric+oxide+against+oxidative+stress+under+ultraviolet-B+radiation%2E&journal=Nitric+Oxide&author=Shi+S.&author=Wang+G.&author=Wang+Y.&author=Zhang+L.&author=and+Zhang+L.&publication_year=2005&volume=13&pages=1-9
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                                            [243] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Mechanism+of+superoxide+dismutase%2FH2O2-mediated+nitric+oxide+release+from+S-nitrosoglutathione-role+of+glutamate%2E&journal=Arch%2E+Biochem%2E+Biophys%2E&author=Singh+R.&author=Hogg+N.&author=Goss+S.&author=Antholine+W.&author=and+Kalyanaraman+B.&publication_year=1999&volume=372&pages=8-15
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                                                    [hrefDomain] => doi.org
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                                                )

                                            [246] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Plant+respiration+and+photosynthesis+in+global-scale+models%3A+incorporating+acclimation+to+temperature+and+CO2%2E&journal=Glob%2E++Change+Biol%2E&author=Smith+N.+G.&author=and+Dukes+J.+S.&publication_year=2013&volume=19&pages=45-63
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                                                )

                                            [249] => stdClass Object
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                                                    [text] => Google Scholar
                                                    [href] => http://scholar.google.com/scholar_lookup?&title=The+radiative+signature+of+upper+tropospheric+moistening%2E&journal=Science&author=Soden+B.+J.&author=Jackson+D.+L.&author=Ramaswamy+V.&author=Schwarzkopf+M.+D.&author=and+Huang+X.&publication_year=2005&volume=310&pages=841-844
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                                                )

                                            [252] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+protects+against+oxidative+stress+under+heat+stress+in+the+calluses+from+two+ecotypes+of+reed%2E&journal=Plant+Sci%2E&author=Song+L.&author=Ding+W.&author=Zhao+M.&author=Sun+B.&author=and+Zhang+L.&publication_year=2006&volume=171&pages=449-458
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                                            [255] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Behind+the+scenes%3A+the+roles+of+reactive+oxygen+species+in+guard+cells%2E&journal=New+Phytol%2E&author=Song+Y.&author=Miao+Y.&author=and+Song+C.+P.&publication_year=2014&volume=201&pages=1121-1140
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Contemporary+evolution+meets+conservation%2E&journal=Trends+Ecol%2E++Evol%2E&author=Stockwell+C.&author=Hendry+A.&author=and+Kinnison+M.&publication_year=2003&volume=18&pages=94-101
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                                                )

                                            [260] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=An+increase+in+the+concentration+of+abscisic+acid+is+critical+for+nitric+oxide-mediated+plant+adaptive+responses+to+UV-B+irradiation%2E&journal=New+Phytol%2E&author=Tossi+V.&author=Lamattina+L.&author=and+Cassia+R.&publication_year=2009&volume=181&pages=871-879
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                                                )

                                            [262] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Effects+of+hydrogen+peroxide+and+nitric+oxide+on+both+salt+and+heat+stress+tolerance+in+rice%2E&journal=Plant+Sci%2E&author=Uchida+A.&author=Jagendorf+A.+T.&author=Hibino+T.&author=Takabe+T.&author=and+Takabe+T.&publication_year=2002&volume=163&pages=515-523
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                                                )

                                            [265] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Plant+signalling+in+acute+ozone+exposure%2E&journal=Plant+Cell+Environ%2E&author=Vainonen+J.+P.&author=and+Kangasjärvi+J.&publication_year=2015&volume=38&pages=240-252
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                                            [268] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Flood+adaptive+traits+and+processes%3A+an+overview%2E&journal=New+Phytol%2E&author=Voesenek+L.++A.&author=and+Bailey-Serres+J.&publication_year=2015&volume=206&pages=57-73
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                                            [270] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Elevated+carbon+dioxide+induces+stomatal+closure+of+Arabidopsis+thaliana+%28L%2E%29+heynh%2E++through+an+increased+production+of+nitric+oxide%2E&journal=J%2E+Plant+Growth+Regul%2E&author=Wang+H.&author=Xiao+W.&author=Niu+Y.&author=Chai+R.&author=Jin+C.&author=and+Zhang+Y.&publication_year=2015&volume=34&pages=372-380
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                                            [271] => stdClass Object
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                                                    [href] => https://doi.org/10.1016/S0012-8252(01)00062-9
                                                    [hrefDomain] => doi.org
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                                                )

                                            [272] => stdClass Object
                                                (
                                                    [text] => Google Scholar
                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Atmospheric+methane+and+global+change%2E&journal=Earth+Sci%2E+Rev%2E&author=Wuebbles+D.+J.&author=and+Hayhoe+K.&publication_year=2002&volume=57&pages=177-210
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                                                    [isOutbound] => 1
                                                )

                                            [273] => stdClass Object
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                                                    [href] => https://doi.org/10.1104/pp.114.237925
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                                                )

                                            [275] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Reactive+oxygen+species-dependent+nitric+oxide+production+contributes+to+hydrogen-promoted+stomatal+closure+in+Arabidopsis%2E&journal=Plant+Physiol%2E&author=Xie+Y.&author=Mao+Y.&author=Zhang+W.&author=Lai+D.&author=Wang+Q.&author=and+Shen+W.&publication_year=2014&volume=165&pages=759-773
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                                                )

                                            [278] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Elevated-CO2+response+of+stomata+and+its+dependence+on+environmental+factors%2E&journal=Front%2E+Plant+Sci%2E&author=Xu+Z.&author=Jiang+Y.&author=Jia+B.&author=and+Zhou+G.&publication_year=2016
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                                                    [isOutbound] => 1
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                                                    [hrefDomain] => doi.org
                                                    [isOutbound] => 1
                                                )

                                            [281] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Response+and+adaptation+of+photosynthesis%2C+respiration%2C+and+antioxidant+systems+to+elevated+CO2+with+environmental+stress+in+plants%2E&journal=Front%2E++Plant+Sci%2E&author=Xu+Z.&author=Jiang+Y.&author=and+Zhou+G.&publication_year=2015
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                                                    [isOutbound] => 1
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                                                    [isOutbound] => 1
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                                                    [hrefDomain] => doi.org
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                                                )

                                            [284] => stdClass Object
                                                (
                                                    [text] => Google Scholar
                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Nitric+oxide+alleviates+oxidative+damage+induced+by+enhanced+ultraviolet-B+radiation+in+cyanobacterium%2E&journal=Curr%2E+Microbiol%2E&author=Xue+L.&author=Li+S.&author=Sheng+H.&author=Feng+H.&author=Xu+S.&author=and+An+L.&publication_year=2007&volume=55&pages=294-301
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                                                    [isOutbound] => 1
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                                                    [isOutbound] => 1
                                                )

                                            [287] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Contrasting+responses+of+leaf+stomatal+characteristics+to+climate+change%3A+a+considerable+challenge+to+predict+carbon+and+water+cycles%2E&journal=Glob%2E+Chang%2E+Biol%2E&author=Yan+W.&author=Zhong+Y.&author=and+Shangguan+Z.&publication_year=2017&volume=23&pages=3781-3793
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                                                )

                                            [290] => stdClass Object
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=S+-Nitrosylation+positively+regulates+ascorbate+peroxidase+activity+during+plant+stress+responses%2E&journal=Plant+Physiol%2E&author=Yang+H.&author=Mu+J.&author=Chen+L.&author=Feng+J.&author=Hu+J.&author=Li+L.&publication_year=2015&volume=167&pages=1604-1615
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                                                )

                                            [293] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=S-nitrosylation+of+NADPH+oxidase+regulates+cell+death+in+plant+immunity%2E&journal=Nature&author=Yun+B.-W.&author=Feechan+A.&author=Yin+M.&author=Saidi+N.+B.&author=Le+Bihan+T.&author=Yu+M.&publication_year=2011&volume=478&pages=264-268
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Increased+abscisic+acid+levels+in+transgenic+tobacco+over-expressing+9+cis-epoxycarotenoid+dioxygenase+influence+H2O2+and+NO+production+and+antioxidant+defenses%2E&journal=Plant+Cell+Environ%2E&author=Zhang+Y.&author=Tan+J.&author=Guo+Z.&author=Lu+S.&author=He+S.&author=Shu+W.&publication_year=2009&volume=32&pages=509-519
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                                            [299] => stdClass Object
                                                (
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                                                    [href] => http://scholar.google.com/scholar_lookup?&title=Physiological%2C+biochemical%2C+and+genome-wide+transcriptional+analysis+reveals+that+elevated+CO2+mitigates+the+impact+of+combined+heat+wave+and+drought+stress+in+Arabidopsis+thaliana+at+multiple+organizational+levels%2E&journal=Glob%2E+Chang%2E+Biol%2E&author=Zinta+G.&author=AbdElgawad+H.&author=Domagalska+M.+A.&author=Vergauwen+L.&author=Knapen+D.&author=Nijs+I.&publication_year=2014&volume=20&pages=3670-3685
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                                    Plant Abiotic Stress


                                
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                            [body] => Frontiers in Plant Science Plant Abiotic Stress . Articles Suggest a Research Topic > REVIEW article . Front. Plant Sci., 01 March 2018 | https://doi.org/10.3389/fpls.2018.00273 Climate Change and the Impact of Greenhouse Gasses: CO2 and NO, Friends and Foes of Plant Oxidative Stress Raúl Cassia*, Macarena Nocioni, Natalia Correa-Aragunde and Lorenzo Lamattina Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata-Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Argentina Here, we review information on how plants face redox imbalance caused by climate change, and focus on the role of nitric oxide (NO) in this response. Life on Earth is possible thanks to greenhouse effect. Without it, temperature on Earth’s surface would be around -19∘C, instead of the current average of 14∘C. Greenhouse effect is produced by greenhouse gasses (GHG) like water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxides (NxO) and ozone (O3). GHG have natural and anthropogenic origin. However, increasing GHG provokes extreme climate changes such as floods, droughts and heat, which induce reactive oxygen species (ROS) and oxidative stress in plants. The main sources of ROS in stress conditions are: augmented photorespiration, NADPH oxidase (NOX) activity, β-oxidation of fatty acids and disorders in the electron transport chains of mitochondria and chloroplasts. Plants have developed an antioxidant machinery that includes the activity of ROS detoxifying enzymes [e.g., superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX), and peroxiredoxin (PRX)], as well as antioxidant molecules such as ascorbic acid (ASC) and glutathione (GSH) that are present in almost all subcellular compartments. CO2 and NO help to maintain the redox equilibrium. Higher CO2 concentrations increase the photosynthesis through the CO2-unsaturated Rubisco activity. But Rubisco photorespiration and NOX activities could also augment ROS production. NO regulate the ROS concentration preserving balance among ROS, GSH, GSNO, and ASC. When ROS are in huge concentration, NO induces transcription and activity of SOD, APX, and CAT. However, when ROS are necessary (e.g., for pathogen resistance), NO may inhibit APX, CAT, and NOX activity by the S-nitrosylation of cysteine residues, favoring cell death. NO also regulates GSH concentration in several ways. NO may react with GSH to form GSNO, the NO cell reservoir and main source of S-nitrosylation. GSNO could be decomposed by the GSNO reductase (GSNOR) to GSSG which, in turn, is reduced to GSH by glutathione reductase (GR). GSNOR may be also inhibited by S-nitrosylation and GR activated by NO. In conclusion, NO plays a central role in the tolerance of plants to climate change. Introduction. Life on Earth, as it is, relies on the natural atmospheric greenhouse effect. This is the result of a process in which a planet’s atmosphere traps the sun radiation and warms the planet’s surface. Greenhouse effect occurs in the troposphere (the lower atmosphere layer), where life and weather occur. In the absence of greenhouse effect, the average temperature on Earth’s surface is estimated around -19°C, instead of the current average of 14°C (Le Treut et al., 2007). Greenhouse effect is produced by greenhouse gasses (GHG). GHG are those gaseous constituents of the atmosphere that absorb and emit radiation in the thermal infrared range (IPCC, 2014). Traces of GHG, both natural and anthropogenic, are present in the troposphere. The most abundant GHG in increasing order of importance are: water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxides (NxO) and ozone (O3) (Kiehl and Trenberth, 1997). GHG percentages vary daily, seasonally, and annually. GHG Contribute Differentially to Greenhouse Effect. Water Vapor. Water is present in the troposphere both as vapor and clouds. Water vapor was reported by Tyndal in 1861 as the most important gaseous absorber of variations in infrared radiation (cited in Held and Souden, 2000). Further accurate calculation estimate that water vapor and clouds are responsible for 49 and 25%, respectively, of the long wave (thermal) absorption (Schmidt et al., 2010). However, atmospheric lifetime of water vapor is short (days) compared to other GHG as CO2 (years) (IPCC, 2014). Water vapor concentrations are not directly influenced by anthropogenic activity and vary regionally. However, human activity increases global temperatures and water vapor formation indirectly, amplifying the warming in a process known as water vapor feedback (Soden et al., 2005). Carbon Dioxide (CO2). Carbon dioxide is responsible for 20% of the thermal absorption (Schmidt et al., 2010). Natural sources of CO2 include organic decomposition, ocean release and respiration. Anthropogenic CO2 sources are derived from activities such as cement manufacturing, deforestation, fossil fuels combustion such as coal, oil and natural gas, etc. Surprisingly, 24% of direct CO2 emission comes from agriculture, forestry and other land use, and 21% comes from industry (IPCC, 2014). Atmospheric CO2 concentrations climbed up dramatically in the past two centuries, rising from around 270 μmol.mol-1 in 1750 to present concentrations higher than 385 μmol.mol-1 (Mittler and Blumwald, 2010; IPCC, 2014). Around 50% of cumulative anthropogenic CO2 emissions between 1750 and 2010 have taken place since the 1970s (IPCC, 2014). It is calculated that the temperature rise produced by high CO2 concentrations, plus the water positive feedback, would increase by 3–5°C the global mean surface temperature in 2100 (IPCC, 2014). Methane (CH4). Methane (CH4) is the main atmospheric organic trace gas. CH4 is the primary component of natural gas, a worldwide fuel source. Significant emissions of CH4 result from cattle farming and agriculture, but mainly as a consequence of fossil fuel use. Concentrations of CH4 were multiplied by two since the pre-industrial era. The present worldwide-averaged concentration is of 1.8 μmol.mol-1 (IPCC, 2014). Although its concentration represents only 0.5% that of CO2, concerns arise regarding a jump in CH4 atmospheric release. Indeed, it is 30 times more powerful than CO2 as GHG (IPCC, 2014). CH4 generates O3 (see below), and along with carbon monoxide (CO), contributes to control the amount of OH in the troposphere (Wuebbles and Hayhoe, 2002). Nitrous Oxides (NxO). Nitrous oxide (N2O) and nitric oxide (NO) are GHG. During the last century, their global emissions have rised, due mainly to human intervention (IPCC, 2014). The soil emits both N2O and NO. N2O is a strong GHG, whereas NO contributes indirectly to O3 synthesis. As GHG, N2O is potentially 300 times stronger than CO2. Once in the stratosphere, the former catalyzes the elimination of O3 (IPCC, 2014). In the atmosphere, N2O concentrations are climbing up due mainly to microbial activity in nitrogen (N)-rich soils related with agricultural and fertilization practices (Hall et al., 2008). Anthropogenic emissions (from combustion of fossil fuels) and biogenic emissions from soils are the main sources of NO in the atmosphere (Medinets et al., 2015). In the troposphere, NO quickly oxidizes to nitrogen dioxide (NO2). NO and NO2 (termed as NOx) may react with volatile organic compounds (VOCs) and hydroxyl, resulting in organic nitrates and nitric acid, respectively. They access ecosystems through atmospheric deposition that has an impact on the N cycle as a result of acidification or N enrichment (Pilegaard, 2013). NO Sources and Chemical Reactions in Plants. Two major pathways for NO production have been described in plants: the reductive and the oxidative pathways. The reductive pathway involves the reduction of nitrite to NO by NR under conditions such as acidic pH, anoxia, or an increase in nitrite levels (Rockel et al., 2002; Meyer et al., 2005). NR-dependent NO formation has been involved in processes such as stomatal closure, root development, germination and immune responses. In plants, nitrite may also be reduced enzymatically by other molybdenum enzymes such as, xanthine oxidase, aldehyde oxidase, and sulfite oxidase, in animals (Chamizo-Ampudia et al., 2016) or via the electron transport system in mitochondria (Gupta and Igamberdiev, 2016). The oxidative pathway produces NO through the oxidation of organic compounds such as polyamines, hydroxylamine and arginine. In animals, NOS catalyzes arginine oxidation to citrulline and NO. Many efforts were made to find the arginine-dependent NO formation in plants, as well as of plant NOS (Frohlich and Durner, 2011). The identification of NOS in the green alga Ostreococcus tauri (Foresi et al., 2010) led to high-throughput bioinformatic analysis in plant genomes. This study shows that NOS homologs were not present in over 1,000 genomes of higher plants analyzed, but only in few photosynthetic microorganisms, such as algae and diatoms (Di Dato et al., 2015; Kumar et al., 2015; Jeandroz et al., 2016). In summary, although an arginine-dependent NO production is found in higher plants, the specific enzyme/s involved in the oxidative pathways remain elusive. Ozone (O3). Ozone (O3) is mainly found in the stratosphere, but a little amount is generated in the troposphere. Stratospheric ozone (namely the ozone layer) is formed naturally by chemical reactions involving solar ultraviolet (UV) radiation and O2. Solar UV radiation breaks one O2 molecule, producing two oxygen atoms (2 O). Then, each of these highly reactive atoms combines with O2 to produce an (O3) molecule. Almost 99% of the Sun’s medium-frequency UV light (from about 200 to 315 nm wavelength) is absorbed by the (O3) layer. Otherwise, they could damage exposed life forms near the Earth surface1. The majority of tropospheric O3 appears when NOx, CO and VOCs, react in the presence of sunlight. However, it was reported that NOx may scavenge O3 in urban areas (Gregg et al., 2003). This dual interaction between NOx and O3 is influenced by light, season, temperature and VOC concentration (Jhun et al., 2015). Besides, the oxidation of CH4 by OH in the troposphere gives way to formaldehyde (CH2O), CO, and O3, in the presence of high amounts of NOx1. Tropospheric O3 is harmful to both plants and animals (including humans). O3 affects plants in several ways. Stomata are the cells, mostly on the underside of the plant leaves, that allow CO2 and water to diffuse into the tissue. High concentrations of O3 cause plants to close their stomata (McAdam et al., 2017), slowing down photosynthesis and plant growth. O3 may also provoke strong oxidative stress, damaging plant cells (Vainonen and Kangasjärvi, 2015). Global Climate Change: an Integrative Balance of the Impact on Plants. Anthropogenic activity alters global climate by interfering with the flows of energy through changes in atmospheric gasses composition, more than the actual generation of heat due to energy usage (Karl and Trenberth, 2003). Short-term consequences of GHG increase in plants are mainly associated with the rise in atmospheric CO2. Plants respond directly to elevated CO2 increasing net photosynthesis, and decreasing stomatal opening (Long et al., 2004). To a lesser extent, O3 uptake by plants may reduce photosynthesis and induce oxidative stress. In the middle and long term, prognostic consensus about climate change signal a rise in CO2 concentration and temperature on the Earth’s surface, unexpected variations in rainfall, and more recurrent and intense weather conditions, e.g., heat waves, drought and flooding events (Mittler and Blumwald, 2010; IPCC, 2014). These brief episodes bring plants beyond their capacity of adaptation; decreasing crop and tree yield (Ciais et al., 2005; Zinta et al., 2014). Here we will not discuss plants capacity of adaptation to novel environmental conditions when considering large scales and long-term periods. Ecosystems are being affected by climate change at all levels (terrestrial, freshwater, and marine), and it was already reported that species are under evolutionary adaptation to human-caused climate change (for a review see Scheffers et al., 2016). Migration and plasticity are two biological mechanisms to cope with these changes. Data indicate that each population of a species has limited tolerance to sharp climate variations, and they could migrate to find more favorable environments. Habitat fragmentation limits plant movement, being other big threat for adaptation (Stockwell et al., 2003; Leimu et al., 2010). Despite the fact that individual plants are immobile, plant populations move when seeds are dispersed, resulting in differences in the general distribution of the species (Corlett and Westcott, 2013). In this sense, anthropogenic activities also contribute to seed dispersal. Plasticity is a characteristic related to phenology and phenotype. Phenology is the timing of phases occurrence in the life cycle, and phenotypic plasticity is the range of phenotypes that a single genotype may express depending on its environment (Nicotra et al., 2010). Plasticity is adaptive when the phenotype changes occur in a direction favored by selection in the new environment. Climate Change and ROS. Reactive Oxygen Species (ROS) are continuously generated by plants under normal conditions. However, they are increased in response to different abiotic stresses. One of the most important effects of climate change-related stresses at the molecular level is the increase of ROS inside the cells (Farnese et al., 2016). Among ROS, the most studied are superoxide anion (O2•–), H2O2 and the hydroxyl radical (⋅OH-). Reactive Oxygen Species cause damage to proteins, lipids and DNA, affecting cell integrity, morphology, physiology, and, consequently, the growth of plants (Frohnmeyer and Staiger, 2003). The main sources of ROS in stress conditions are: augmented photorespiration, NADPH oxidase (NOX) activity, β-oxidation of fatty acids and disorders in the electron transport chains of mitochondrias and chloroplasts (Apel and Hirt, 2004; AbdElgawad et al., 2015). Hence, higher plants have evolved in the presence of ROS and have acquired pathways to protect themselves from its toxicity. Plant antioxidant system (AS) includes the activity of ROS detoxifying enzymes [e.g., superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione peroxidase (GPX), and peroxiredoxin (PRX)], as well as antioxidant molecules such as ascorbic acid (ASC) and glutathione (GSH) that are present in almost all subcellular compartments (reviewed by Choudhury et al., 2017). In this context, plants have also developed a tight interaction between ROS and NO as a mechanism to reduce the deleterious consequences of these ROS-induced oxidative injuries. NO orchestrates a wide range of mechanisms leading to the preservation of redox homeostasis in plants. Consequently, NO at low concentration is considered a broad-spectrum anti-stress molecule (Lamattina et al., 2003; Tossi et al., 2009; Correa-Aragunde et al., 2015). Figure 1 shows the relationship among the different GHG and their impact on plants. FIGURE 1 FIGURE 1. Simplified scheme showing greenhouse gasses (GHG) and their effects on plants. GHG (H2O vapor, clouds, CO2, CH4, N2O, and NO) have both natural and anthropogenic origin, contributing to greenhouse effect. Short-term effects of GHG increase is mainly CO2 rise, that activates photosynthesis (PS) and inhibits stomatal opening (SO). Long-term effects of GHG increase are extreme climate changes such as floods, droughts, heat. All of them induce the generation of reactive oxygen species (ROS) and oxidative stress in plants. Nitric oxide (NO) could alleviate oxidative stress by scavenging ROS and/or regulating the antioxidant system (AS). GHG and volatile organic compounds (VOC) react in presence of sunlight (E#) to give tropospheric O3. Although tropospheric O3 is prejudicial for life, stratospheric O3 is beneficial, because filters harmful UV-B radiation. The size of arrows are representative of the GHG concentration. CO2 and NO Contribute to Regulate Redox Homeostasis in Plants. CO2 Increasing: Advantages and Disadvantages. Increased CO2 was suggested to have a “fertilization” effect, because crops would increase their photosynthesis and stomatal conductance in response to elevated CO2. This belief was supported by studies performed in greenhouses, laboratory controlled-environment chambers, and transparent field chambers, where emitted CO2 may be held back and readily controlled (Drake et al., 1997; Markelz et al., 2014). However, more realistic results, obtained by Free-Air Concentration Enrichment (FACE) technology, suggest that the fertilization response due to CO2 increase is probably dependent on genetic and environmental factors, and the duration of the study (Smith and Dukes, 2013). An extensive review of the literature in this field made by Xu et al. (2015) concluded that augmented CO2 normally increases photosynthesis in C3 species such as rice, soybean and wheat. On the other hand, they pointed out that a negative feedback of photosynthesis could take place in augmented CO2, as a result of overload of chemical and reactive generated substrates, leading to an imbalance in the sink:source carbon ratio. Moreover, the energetic cost of carbohydrate exportation increases in elevated CO2 level. The most important photosynthetic enzyme is the ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO). Rubisco is located in mesophyll cells of C3 plants, in direct contact with the intercellular air space linked to the atmosphere by epidermal stomatal pores. Photosynthesis increases at high CO2, because Rubisco is not CO2 saturated and CO2 inhibits the oxygenation reactions and photorespiration (Long et al., 2006). However, long-term high concentration of CO2 may down regulate Rubisco activity because ribulose-1,5-bisphosphate is not regenerated. Hexokinase (HXK), a sensor of extreme photosynthate, may participate in the down regulation of Rubisco concentration (Xu et al., 2015). Moreover, severe abiotic stresses, such as temperature and drought, may restrain Rubisco carboxylation and foster oxygenation (Xu et al., 2015). In C4 crops, such as maize and sorghum, the elevated concentration of CO2 inside the bundle sheath cells could prevent a large increase of Rubisco activity at higher atmospheric CO2 and, thereby, photosynthetic activity is not augmented. However, at high CO2 levels, the water status of C4 plants under drought conditions is improved, increasing photosynthesis and biomass accumulation (Long et al., 2006; Mittler and Blumwald, 2010). That envisages potential advantages for the C4 species in future climatic change scenarios, particularly in arid and semiarid areas. In addition, high CO2 has the benefit of reducing stomatal conductance, decreasing 10% evapotranspiration in both C3 and C4 plants. Simultaneously, the cooling decreased resulting from reduced transpiration causes elevated canopy temperatures of around 0.7°C for most crops. Biomass and yield rise due to high CO2 in all C3 plants, but not in C4 plants exception made when water is a restraint. Yields of C3 grain crops jump around 19% on average at high CO2 (Kimball, 2016). Some reports analyze the contribution of CO2 in the responses of plants to the combination of multiple stresses. For Arabidopsis thaliana, the combination of heat and drought induces photosynthesis inhibition of 62% under ambient CO2, but the drop in photosynthesis is just 40% at high CO2. Moreover, the protein oxidation increases significantly during a heat wave and drought, and this effect is repressed by increased CO2. Photorespiration is also reduced by high CO2 (Zinta et al., 2014). Studying grasses (Lolium perenne, Poa pratensis) and legumes (Medicago lupulina, Lotus corniculatus) exposed to drought, high temperature and augmented CO2, AbdElgawad et al. (2015) demonstrated that drought suppresses plant growth, photosynthesis and stomatal conductance, and promotes in all species the synthesis of osmolytes and antioxidants. Instead, oxidative damage is more markedly observed in legumes than in grasses. In general, warming amplifies drought consequences. In contrast, augmented CO2 diminishes stress impact. Reduction in photosynthesis and chlorophyll, as a result of drought and elevated temperature, were avoided by high CO2 in the grasses. Noxious effects of oxidative stress, i.e., lipid peroxidation, are phased down in all species by augmented CO2. Normally, a reduced impact of oxidative stress is due to decreased photorespiration and diminished NOX activity. In legumes, a rise in levels of antioxidant molecules (flavonoids and tocopherols) contribute as well to the stress mitigation caused by augmented CO2. The authors draw the conclusion that these different responses point at an unequal future impact of climate change on the production of agricultural-scale legumes and grass crops. Kumari et al. (2015) assessed the impact of various levels of CO2, ambient (382 ppm) and augmented (570 ppm), and O3, ambient (50 ppb) and augmented (70 ppb) on the potato physiological and biochemical responses (Solanum tuberosum). They observed that augmented CO2 cut down O3 uptake, enhanced carbon assimilation, and curbed oxidative stress. Elevated CO2 also mitigated the noxious effect of high O3 on photosynthesis. Although some molecular mechanisms underpinning CO2 actions are unknown, the results presented highlight the importance of CO2 as a regulator that mitigates the potential climate change-induced deleterious consequences in plants. Recent reports suggest that some CO2-associated responses may be mediated by NO. Du et al. (2016) determined that 800 μmol.mol-1 of CO2 increased the NO concentration in Arabidopsis leaves, through a mechanism related to nitrate availability. Moreover, NO increase, as a consequence of high CO2 levels, was reported as a general procedure to improve iron (Fe) nutrition in response to Fe deficiency in tomato roots (Jin et al., 2009). The gas exchange between the atmosphere and plants is mainly regulated by stomata. But structure and physiology of stomata are also influenced by gasses (García-Mata and Lamattina, 2013). Elevated CO2 regulate stomatal density and conductance. Moreover, there is increasing evidence that this response is modified by interaction of CO2 with other environmental factors (Xu et al., 2016; Yan et al., 2017). Wang et al. (2015) reported that 800 μmol.mol-1 of CO2 increases the NO concentration in A. thaliana guard cells, inducing stomatal closure. Both NR and NO synthase (NOS)-like activities are necessary for CO2-induced NO accumulation. Comprehensive pharmacological and genetic results obtained in Arabidopsis by Chater et al. (2015), show that when CO2 concentration is around 700–1000 ppm, stomatal density and closure are reduced. They also illustrate that those elements necessary for this process are: activation of both ABA biosynthesis genes and the PYR/RCAR ABA receptor, and ROS increase. However, Shi et al. (2015) provide genetic and pharmacological evidence that high CO2 concentration induces stomatal closure by an ABA-independent mechanism in tomato. They show that 800 μmol.mol-1 of CO2 increase the expression of the protein kinase OPEN STOMATA 1 (OST1), NOX, and nitrate reductase (NR) genes. They also show that the sequential production of NOX-dependent H2O2 and NR-produced NO are mainly dependent of OST1, and are involved in the CO2-induced stomatal closure. In ABA-dependent mechanisms, ABA is increased by CO2. The binding of ABA to its receptor (PYR/RCAR) inactivates PP2C, activating OST1. In ABA-independent mechanism, OST1 will be transcriptionally induced by CO2. Once activated, OST1 along with Ca2+, activates NOX, increasing ROS (Kim et al., 2010). The rise of guard cells ROS enhances NO, cytosolic free Ca2+, and pH (Song et al., 2014; Xie et al., 2014). ROS and NO release Ca2+ from internal reservoirs, or influx external Ca2+ through plasma membrane Ca2+in channels. Cytosolic free Ca2+ inactivate inward K+ channels (K+in) to prevent K+ uptake and activate outward K+ channels (K+out) and Cl- (anion) channels (Cl-) at the plasma membrane (Blatt, 2000; García-Mata et al., 2003). Ca2+ also activates slow anion channel homolog 3 (SLAH3), slow anion channel-associated 1 (SLAC1) and aluminum activated malate transporters (ALMT) (Roelfsema et al., 2012). The consequence of the regulation of cation/anion channels is the net efflux of K+/Cl-/malate and influx of Ca2+, making guard cells lose turgor by water outlet, causing stomatal closure. All together, the results discussed here suggest that CO2-induced NO increase is a common plant physiological response to oxidative stresses. Figure 2 shows the importance of CO2 and NO in these processes. FIGURE 2 FIGURE 2. Interplay between CO2 and NO in plant redox physiology: CO2 enters to the leaves by stomata. Once in mesophyll cells, CO2 increase photosynthesis (PS) through the CO2-unsaturated Rubisco activity. When plants are in stress environments, ROS could be augmented by Rubisco-induced photorespiration and NADPH oxidase (NOX) activities. NOX- induced O2•–, in the apoplast is immediately transformed to H2O2 by the superoxide dismutase (SOD). Plasma membrane is permeable to H2O2. CO2 moderates oxidative stress in mesophyll cells by inhibiting both Rubisco photorespiration (PR) and NOX activities. Besides, NO is induced by CO2 and ROS, alleviating the consequences of oxidative stress by scavenging ROS and activating or inhibiting the antioxidant system (AS). In guard cells, CO2 increases the expression and activity of OPEN STOMATA 1 (OST1), in both ABA-dependent and independent mechanisms. OST1 activates NOX, producing ROS and consequently NO increase by nitrate reductase (NR), and NOS-like activities. NO prevents ROS increase by direct scavenging, and inhibiting NOX. NO-dependent Ca2+ regulated ion channels induces stomatal closure, modulating O3 and CO2 uptake, decreasing evapotranspiration, and rising leaf temperature. Abiotic Stress, ROS Generation, and Redox Balance: The Key Role of NO. Reactive oxygen species are generated in apoplast, plasma membrane, chloroplasts, mitochondria, and peroxisomes (Farnese et al., 2016). It was proposed that each stress produces its own “ROS signature” (Choudhury et al., 2017). For instance, drought may reduce the activity of Rubisco, decreasing CO2 fixation and NADP+ regeneration by the Calvin cycle. As a consequence, chloroplast electron transport is altered, generating ROS by electron leakage to O2 (Carvalho, 2008). In drought stress, ROS increase is produced by NOX activity (Farnese et al., 2016). In flooding, ROS generation is an ethylene-promoted process that involves calcium (Ca2+) flux, and NOX activity (Voesenek and Bailey-Serres, 2015). In heat stress, a NOX-dependent transient ROS rise is an early event (Königshofer et al., 2008). Then, endogenous ROS are sensed through histidine kinases, and an Arabidopsis heat stress factor (HsfA4a) appears to sense exogenous ROS. As a result, the MAPK signal pathway is activated (Qu et al., 2013). Moreover, functional decrease in photosynthetic light reaction induces ROS concentration by high electron leakage from the thylakoid membrane (Hasanuzzaman et al., 2013). In this process, O2 is the acceptor, generating O2•–. Thus, individual stresses or their different combinations may produce particular “ROS signatures.” Besides their deleterious effects, ROS are recognized as a signal in the plant reaction to biotic and abiotic stressors. ROS may induce programed cell death (PCD) to avoid pathogen spread (Mur et al., 2008), trigger a systemic defense response signal (Dubiella et al., 2013), or avoid the chloroplast antenna overloading by electrons divert (Choudhury et al., 2017). Whatever the origin and function, ROS concentration must be adequately regulated to avoid excessive concentration and consequent cellular damages. Depending on NO and ROS concentrations, NO has the dual capacity to activate or inhibit the ROS production, and is a key molecule for keeping cellular redox homeostasis under control (Beligni and Lamattina, 1999a; Correa-Aragunde et al., 2015). NO has a direct ROS-scavenging activity because it holds an unpaired electron, reaching elevated reactivity with O2, O2•–, and redox active metals. NO can mitigate OH formation by scavenging either Fe or O2•– (Lamattina et al., 2003). However, NO reacting with ROS (mainly O2•–) may generate reactive nitrogen species (RNS). An excess of RNS originates a nitrosative stress (Corpas et al., 2011). To avoid the toxicity of nitrosative stress, NO is stored as GSNO in the cell. GSH as a Redox Buffer. GSNO as NO Reservoir. SNO and S-Nitrosylation. Glutathione (GSH) is a small peptide with the sequence γ-l-glutamyl-l-cysteinyl-glycine that has a cell redox homeostatic impact in most plant tissues. It is a soluble small thiol considered a non-enzymatic antioxidant. It exists in the reduced (GSH) or oxidized state (GSSG), in which two GSH molecules are joined by a disulfide bond (Rouhier et al., 2008). GSH alleviates oxidative damages in plants generated by abiotic stresses, including salinity, drought, higher, low temperature, and heavy metals. GSH is precursor of phytochelatins, polymers that chelate toxic metals and transport them to the vacuole (Grill et al., 1989). Studies shown that GSH contributes to tolerate nickel, cadmium, zinc, mercury, aluminum and arsenate heavy metals in plants (Asgher et al., 2017). Moreover, GSH has a role in the detoxification of ROS both directly, interacting with them, or indirectly, participating of enzymatic pathways. GSH is involved in glutathionylation, a posttranslational modification that causes a mixed disulfide bond between a Cys residue and GSH. GSH can be oxidized to GSSG by H2O2 and can react with NO to form the nitrosoglutathione (GSNO) derivative. GSNO is an intracellular NO reservoir. It is also a vehicle of NO throughout the cell and organs, spreading NO biological function. GSNO is the largest low-molecular-mass S-nitrosothiol (SNO) in plant cells (Corpas et al., 2013). GSNO metabolism and its reaction with other molecules involve S-nitrosylation and S-transnitrosation which consist of the binding of a NO molecule to a cysteine residue in proteins. Thioredoxin produces protein denitrosylation (Correa-Aragunde et al., 2013). GSNO could be decomposed by the GSNO reductase (GSNOR) to GSSG which, in turn, is reduced to GSH by glutathione reductase (GR). Glutathione also participates in the GSH/ASC cycle, a series of enzymatic reactions that degrade H2O2. APX degrades H2O2 using ASC, the other major antioxidant in plants, as cofactor. The oxidized ASC is reduced by monodehydroascorbate reductase (MDHAR) in an NAD(P)H-dependent manner and by dehydroascorbate reductase (DHAR) employing GSH as electron donor. The resulting GSSG is reduced in turn to GSH by GR (Foyer and Noctor, 2011). Different Effects of NO in the Regulation of Antioxidant Enzymes. The application of NO donors alleviates oxidative stress in plants challenged to abiotic and/or biotic stresses (Laxalt et al., 1997; Beligni and Lamattina, 1999b, 2002; Shi et al., 2007; Xue et al., 2007; Leitner et al., 2009). Besides the direct ROS-scavenging activity of NO, its beneficial effect is exerted by the regulation of the antioxidant enzymes activity that controls toxic levels of ROS and RNS (Uchida et al., 2002; Shi et al., 2005; Song et al., 2006; Romero-Puertas et al., 2007; Bai et al., 2011). NO can modulate cell redox balance in plants through the regulation of gene expression, posttranslational modification or by its binding to the heme prosthetic group of some antioxidant enzymes. SOD catalyzes the dismutation of stress-generated O2•– in one of two less harmful species: either molecular oxygen (O2) or hydrogen peroxide (H2O2). APX and CAT are the most important enzymes degrading H2O2 in plants. They transform H2O2 to H2O and O2. APX isoforms are primarily found in the cytosol and chloroplasts, while the CAT isoforms are found in peroxisomes. APX has strong affinity for H2O2 and uses ASC as an electron donor. In contrast, CAT removes H2O2 generated in the peroxisomal respiratory pathway without the need to reduce power. Even though CAT affinity for H2O2 is low, its elevated rate of reaction offers an effective way to detoxify H2O2 inside the cell. PRX may reduce both hydroperoxide and peroxynitrite. Many reports on different plant species demonstrate that NO induces the transcription and activity of antioxidative enzymes in response to oxidative stress. The tolerance to drought and salt-induced oxidative stress in tobacco is related to the ABA-triggered production of H2O2 and NO. In turn, they induce transcripts and activities of SOD, CAT, APX, and GR (Zhang et al., 2009). UV-B-produced oxidative stress in Glycine max was alleviated by NO donors, which induced transcription and activities of SOD, CAT, and APX (Santa-Cruz et al., 2014). Furthermore, in bean leaves, SOD, CAT, and APX activities are increased by NO donors, and protected from the oxidative stress generated by UV-B irradiation (Shi et al., 2005). Drought tolerance in bermudagrass is improved by ABA-dependent SOD and CAT activities. This effect is regulated by H2O2 and NO, NO acting downstream H2O2 (Lu et al., 2009). Several antioxidant enzymes have been identified as target of S-nitrosylation, resulting in a change of their biological activity (Romero-Puertas et al., 2008; Bai et al., 2011; Fares et al., 2011). For instance, NO reinforces recalcitrant seed desiccation tolerance in Antiaris toxicaria by activating the ascorbate-glutathione cycle through S-nitrosylation to control H2O2 accumulation. Desiccation treatment reduced the level of S-nitrosylated APX, GR, and DHAR proteins. Instead, NO gas exposure activated them by S-nitrosylation (Bai et al., 2011). Furthermore, APX was S-nitrosylated at Cys32 during saline stress and biotic stress, enhancing its enzymatic activity (Begara-Morales et al., 2014; Yang et al., 2015). In addition, auxin-induced denitrosylation of cytosolic APX provoked inhibition of its activity, followed by an increase of H2O2 concentration and the consequent lateral root formation in Arabidopsis (Correa-Aragunde et al., 2013). Moreover, an inhibitory impact of S-nitrosylation on APX activity was also reported during programmed cell death in Arabidopsis (de Pinto et al., 2013). CAT was identified to be S-nitrosylated in a proteomic study of isolated peroxisomes (Ortega-Galisteo et al., 2012). A decrease of S-nitrosylated CAT under Cd treatment was reported. In addition, in vitro experiments demonstrated a reversible inhibitory effect of APX and CAT activities by NO binding to the Fe of the heme cofactor (Brown, 1995; Clark et al., 2000). In addition, NOXs have been involved in plant defense, development, hormone biosynthesis and signaling (Marino et al., 2012). Whereas S-nitrosylation did not affect SOD activities, nitration inhibited Mn-SOD1, Fe-SOD3, and CuZn-SOD3 activity to different degrees (Holzmeister et al., 2015). SOD isoforms could also regulate endogenous NO availability by competing for the common substrate, O2•–, and it was demonstrated that bovine SOD may release NO from GSNO (Singh et al., 1999). When GSNO is decomposed by GSNOR, it produces GSSG. GSNOR is also regulated by NO. Frungillo et al. (2014) demonstrated that NO-derived from nitrate assimilation in Arabidopsis inhibited GSNOR1 by S-nitrosylation, preventing GSNO degradation. They proposed that (S)NO controls its own generation and scavenging by modulating nitrate assimilation and GSNOR1 activity. It was also shown that chilling treatment in poplar increased S-nitrosylation of NR, along with a significant decrease of its activity (Cheng et al., 2015). The dual activity of Prx, suggests a role for this enzyme both in ROS and RNS regulation. S-nitrosylation of Arabidopsis PrxIIE inhibits its peroxynitrite activity, increasing peroxynitrite-mediated tyrosine nitration (Romero-Puertas et al., 2007). Pea mitochondrial PrxIIF was S-nitrosylated under salt stress, and its peroxidase activity was reduced by 5 mM GSNO (Camejo et al., 2013). An interesting study demonstrated that NO controls hypersensitive response (HR) through S-nitrosylation of NOX, inhibiting ROS synthesis. This triggers a feedback loop limiting HR (Yun et al., 2011). Other proteins related to abiotic stress response are regulated by S-nitrosylation (For a review see Fancy et al., 2017). Figure 3 is a simplified diagram that illustrates the main oxidative and nitrosative effects that modulate the activities of key cell components, thus maintaining cell redox balance. Note the feedback and positive-negative regulatory processes occurring in the main pathways. They involve posttranslational modifications that activate and inhibit the components involved in cell antioxidant system. FIGURE 3 FIGURE 3. Molecules and mechanisms involved in NO-mediated redox balance. H2O2 is generated mainly by NOX and SOD as a response to (a)biotic stress. APX and CAT are the main H2O2-degrading enzymes. NO is increased by H2O2 through the induction of NR/NOS-like activities, and may scavenge ROS or induce both the transcription and activity of SOD, CAT, and APX. In parallel, NO is combined with GSH to form nitrosoglutathione GSNO. GSNO regulates many enzymatic activities by the posttranslational modification of cysteine residues through S-Nitrosylation. NOX and CAT activities are inhibited by S-nitrosylation, whereas APX is either activated or inhibited by S-nitrosylation. NO also inhibits APX by binding to heme group. GSNO is degraded by GSNOR, which could be inhibited by H2O2 and S-nitrosylation.NR could be inhibited by S-nitrosylation. GR reduces GSSG to GSH, and it is activated by S-nitrosylation. Ascorbate (ASC) is a cofactor of APX. Reduced ASC is generated by MDHAR and DHAR, using GSH as electron donor. Both enzymes are inhibited by S-nitrosylation. Reactive Nitrogen Species (RNS) may be originated by NO and O2•– reaction. SOD regulate RNS dismutating O2•–. Peroxiredoxins (Prx) reduce both ROS AND RNS. RNS are degraded by PrxIIe, and H2O2 by PrxIIF. Both enzymes are inhibited by S-nitrosylation. Red lines: H2O2-regulated reactions. Purple lines: NO-regulated reactions. Green lines: GSNO-regulated reactions. Conclusions and Perspectives. The accelerating rate of climate change, together with habitat fragmentation caused by human activity, are part of the selective pressures building a new Earth’s landscape. Climate change is a multidimensional and simultaneous variation in duration, frequency and intensity of parameters like temperature and precipitation, altering the seasons and life on the Earth. In this scenario, plant species with increased adaptive plasticity will be better equipped to tolerate changes in the frequency of extreme weather events. GHG are one of the forces driving climate change. However, CO2 and NO may contribute to maintaining the cell redox homeostasis, regulating the amount of ROS, GSH, GSNO, and SNO. In this manuscript, we summarize the available evidence supporting the presence of broad spectrum anti-stress molecules, as NO in plants, for coping with unprecedented changes in environmental conditions. Future research should focus in better understanding the influence of GHG on plant physiology. Author Contributions. RC conceived the project and wrote the manuscript. MN drew figures and collaborated in writing the manuscript. NC-A and LL supervised and complemented the drafting. All the persons entitled to authorship have been named and have approved the final version of the submitted manuscript. Funding. This work was supported by grants from the Consejo Nacional de Investigaciones Cientificas y Tecnicas, the Agencia Nacional de Promoción Científica y Tecnológica, and the Universidad Nacional de Mar del Plata, Argentina. NC-A, LL, and RC are permanent members of the Scientific Research career of CONICET. MN is doctoral fellow of the ANPCYT. Conflict of Interest Statement. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer MCR-P and handling Editor declared their shared affiliation. Acknowledgments. We thank ANPCYT for MN fellowship. We also thank Marta Terrazo for helping with the language revision of the manuscript. Footnotes. ^ https://ozonewatch.gsfc.nasa.gov/facts/ozone.html References. AbdElgawad, H., Farfan-Vignolo, E. R., de Vos, D., and Asard, H. (2015). Elevated CO2 mitigates drought and temperature-induced oxidative stress differently in grasses and legumes. Plant Sci. 231, 1–10. doi: 10.1016/j.plantsci.2014.11.001 PubMed Abstract | CrossRef Full Text | Google Scholar Apel, K., and Hirt, H. (2004). Reactive oxygen species: metabolism, oxidative stress, and signal transduction. Annu. Rev. Plant Biol. 55, 373–399. doi: 10.1146/annurev.arplant.55.031903.141701 PubMed Abstract | CrossRef Full Text | Google Scholar Asgher, M., Per, T. S., Anjum, S., Khan, M., Masood, A., Verna, S., et al. (2017). “Contribution of glutathione in heavy metal stress tolerance in plants,” in Reactive Oxygen Species and Antioxidant Systems in Plants: Role and Regulation under Abiotic Stress, eds M. Khan and N. Khan (Singapore: Springer), doi: 10.1007/978-981-10-5254-5_12 CrossRef Full Text | Google Scholar Bai, X., Yang, L., Tian, M., Chen, J., Shi, J., Yang, Y., et al. (2011). Nitric oxide enhances desiccation tolerance of recalcitrant Antiaris toxicaria seeds via protein S-nitrosylation and carbonylation. PLoS One 6:e20714. doi: 10.1371/journal.pone.0020714 PubMed Abstract | CrossRef Full Text | Google Scholar Begara-Morales, J. C., Sánchez-Calvo, B., Chaki, M., Valderrama, R., Mata-Pérez, C., López-Jaramillo, J., et al. (2014). Dual regulation of cytosolic ascorbate peroxidase (APX) by tyrosine nitration and S -nitrosylation. J. Exp. Bot. 65, 527–538. doi: 10.1093/jxb/ert396 PubMed Abstract | CrossRef Full Text | Google Scholar Beligni, M. V., and Lamattina, L. (1999a). Is nitric oxide toxic or protective? Trends Plant Sci. 4, 299–300. doi: 10.1016/S1360-1385(99)01451-X CrossRef Full Text | Google Scholar Beligni, M. V., and Lamattina, L. (1999b). Nitric oxide protects against cellular damage produced by methylviologen herbicides in potato plants. Nitric Oxide 3, 199–208. doi: 10.1006/niox.1999.0222 PubMed Abstract | CrossRef Full Text | Google Scholar Beligni, M. V., and Lamattina, L. (2002). Nitric oxide interferes with plant photo-oxidative stress by detoxifying reactive oxygen species. Plant Cell Environ. 25, 737–748. doi: 10.1046/j.1365-3040.2002.00857.x CrossRef Full Text | Google Scholar Blatt, M. R. (2000). Cellular signaling and volume control in stomatal movements in plants. Annu. Rev. Cell Dev. Biol. 16, 221–241. doi: 10.1146/annurev.cellbio.16.1.221 CrossRef Full Text | Google Scholar Brown, G. C. (1995). Reversible binding and inhibition of catalase by nitric oxide. Eur. J. Biochem. 232, 188–191. doi: 10.1111/j.1432-1033.1995.tb20798.x CrossRef Full Text | Google Scholar Camejo, D., Romero-Puertas, M. D. C., Rodríguez-Serrano, M., Sandalio, L. M., Lázaro, J. J., Jiménez, A., et al. (2013). Salinity-induced changes in S-nitrosylation of pea mitochondrial proteins. J. Proteomics 79, 87–99. doi: 10.1016/j.jprot.2012.12.003 PubMed Abstract | CrossRef Full Text | Google Scholar Carvalho, M. H. C. (2008). Drought stress and reactive oxygen species. Plant Signal. Behav. 3, 156–165. doi: 10.4161/psb.3.3.5536 CrossRef Full Text | Google Scholar Chamizo-Ampudia, A., Sanz-Luque, E., Llamas, A., Ocana-Calahorro, F., Mariscal, V., Carreras, A., et al. (2016). A dual system formed by the ARC and NR molybdoenzymes mediates nitrite-dependent NO production in Chlamydomonas. Plant Cell Environ. 39, 2097–2107. doi: 10.1111/pce.12739 PubMed Abstract | CrossRef Full Text | Google Scholar Cheng, T., Chen, J., Ef, A. A., Wang, P., Wang, G., Hu, X., et al. (2015). Quantitative proteomics analysis reveals that S-nitrosoglutathione reductase (GSNOR) and nitric oxide signaling enhance poplar defense against chilling stress. Planta 242, 1361–1390. doi: 10.1007/s00425-015-2374-5 PubMed Abstract | CrossRef Full Text | Google Scholar Choudhury, F. K., Rivero, R. M., Blumwald, E., and Mittler, R. (2017). Reactive oxygen species, abiotic stress and stress combination. Plant J. 90, 856–867. doi: 10.1111/tpj.13299 PubMed Abstract | CrossRef Full Text | Google Scholar Ciais, P., Reichstein, M., Viovy, N., Granier, A., Ogée, J., Allard, V., et al. (2005). Europe-wide reduction in primary productivity caused by the heat and drought in 2003. Nature 437, 529–533. doi: 10.1038/nature03972 PubMed Abstract | CrossRef Full Text | Google Scholar Clark, D., Durner, J., Navarre, D. A., and Klessig, D. F. (2000). Nitric oxide inhibition of tobacco catalase and ascorbate peroxidase. Mol. Plant. Microbe. Interact. 13, 1380–1384. doi: 10.1006/niox.1999.0222 PubMed Abstract | CrossRef Full Text | Google Scholar Corlett, R. T., and Westcott, D. A. (2013). Will plant movements keep up with climate change? Trends Ecol. Evol. 28, 482–488. doi: 10.1016/j.tree.2013.04.003 PubMed Abstract | CrossRef Full Text | Google Scholar Corpas, F. J., Alché, J. D., and Barroso, J. B. (2013). Current overview of S-nitrosoglutathione (GSNO) in higher plants. Front. Plant Sci. 4:126. doi: 10.3389/fpls.2013.00126 PubMed Abstract | CrossRef Full Text | Google Scholar Corpas, F. J., Leterrier, M., Valderrama, R., Airaki, M., Chaki, M., Palma, J. M., et al. (2011). Nitric oxide imbalance provokes a nitrosative response in plants under abiotic stress. Plant Sci. 181, 604–611. doi: 10.1016/j.plantsci.2011.04.005 PubMed Abstract | CrossRef Full Text | Google Scholar Correa-Aragunde, N., Foresi, N., Delledonne, M., and Lamattina, L. (2013). Auxin induces redox regulation of ascorbate peroxidase 1 activity by S-nitrosylation/denitrosylation balance resulting in changes of root growth pattern in Arabidopsis. J. Exp. Bot. 64, 3339–3349. doi: 10.1093/jxb/ert172 PubMed Abstract | CrossRef Full Text | Google Scholar Correa-Aragunde, N., Foresi, N., and Lamattina, L. (2015). Nitric oxide is a ubiquitous signal for maintaining redox balance in plant cells: regulation of ascorbate peroxidase as a case study. J. Exp. Bot. 66, 2913–2921. doi: 10.1093/jxb/erv073 PubMed Abstract | CrossRef Full Text | Google Scholar Chater, C., Peng, K., Movahedi, M., Dunn, J. A., Walker, H. J., Liang, Y. K., et al. (2015). Elevated CO2-induced responses in stomata require ABA and ABA signaling. Curr. Biol. 25, 2709–2716. doi: 10.1016/j.cub.2015.09.013 PubMed Abstract | CrossRef Full Text | Google Scholar de Pinto, M. C., Locato, V., Sgobba, A., Romero-Puertas, M. D. C., Gadaleta, C., Delledonne, M., et al. (2013). S-Nitrosylation of ascorbate peroxidase is part of programmed cell death signaling in tobacco bright yellow-2 cells. Plant Physiol. 163, 1766–1775. doi: 10.1093/jxb/ert172 PubMed Abstract | CrossRef Full Text | Google Scholar Di Dato, V., Musacchia, F., Petrosino, G., Patil, S., Montresor, M., Sanges, R., et al. (2015). Transcriptome sequencing of three Pseudo-nitzschia species reveals comparable gene sets and the presence of nitric oxide synthase genes in diatoms. Sci. Rep. 5:12329. doi: 10.1038/srep12329 PubMed Abstract | CrossRef Full Text | Google Scholar Drake, B. G., Gonzalez-Meler, M. A., and Long, S. P. (1997). More efficient plants: a consequence of rising atmospheric CO2? Annu. Rev. Plant Physiol. Plant Mol. Biol. 48, 609–639. doi: 10.1146/annurev.arplant.48.1.609 PubMed Abstract | CrossRef Full Text | Google Scholar Du, S., Zhang, R., Zhang, P., Liu, H., Yan, M., Chen, N., et al. (2016). Elevated CO2-induced production of nitric oxide (NO) by NO synthase differentially affects nitrate reductase activity in Arabidopsis plants under different nitrate supplies. J. Exp. Bot. 67, 893–904. doi: 10.1093/jxb/erv506 PubMed Abstract | CrossRef Full Text | Google Scholar Dubiella, U., Seybold, H., Durian, G., Komander, E., Lassig, R., Witte, C. P., et al. (2013). Calcium-dependent protein kinase/NADPH oxidase activation circuit is required for rapid defense signal propagation. Proc. Natl. Acad. Sci. U.S.A. 110, 8744–8749. doi: 10.1073/pnas.1221294110 PubMed Abstract | CrossRef Full Text | Google Scholar Fancy, N. N., Bahlmann, A. K., and Loake, G. J. (2017). Nitric oxide function in plant abiotic stress. Plant Cell Environ. 40, 462–472. doi: 10.1111/pce.12707 PubMed Abstract | CrossRef Full Text | Google Scholar Fares, A., Rossignol, M., and Peltier, J. (2011). Proteomics investigation of endogenous S-nitrosylation in Arabidopsis. Biochem. Biophys. Res. Commun. 416, 331–336. doi: 10.1038/srep12329 PubMed Abstract | CrossRef Full Text | Google Scholar Farnese, F. S., Menezes-Silva, P. E., Gusman, G. S., and Oliveira, J. A. (2016). When bad guys become good ones: the key role of reactive oxygen species and Nitric Oxide in the plant responses to abiotic stress. Front. Plant Sci. 7:471. doi: 10.3389/fpls.2016.00471 PubMed Abstract | CrossRef Full Text | Google Scholar Foresi, N., Correa-Aragunde, N., Parisi, G., Calo, G., Salerno, G., and Lamattina, L. (2010). Characterization of a nitric oxide synthase from the plant kingdom: NO generation from the green alga Ostreococcus tauri is light irradiance and growth phase dependent. Plant Cell 22, 3816–3830. doi: 10.1105/tpc.109.073510 PubMed Abstract | CrossRef Full Text | Google Scholar Foyer, C. H., and Noctor, G. (2011). Ascorbate and glutathione: the heart of the redox hub. Plant Physiol. 155, 2–18. doi: 10.1038/srep12329 PubMed Abstract | CrossRef Full Text | Google Scholar Frohlich, A., and Durner, J. (2011). The hunt for plant nitric oxide synthase (NOS): Is one really needed? Plant Sci. 181, 401–404. doi: 10.1016/j.plantsci.2011.07.014 PubMed Abstract | CrossRef Full Text | Google Scholar Frohnmeyer, H., and Staiger, D. (2003). Ultraviolet-B-radiation-mediated responses in plants. Balancing damage and protection. Plant Physiol. 133, 1420–1428. doi: 10.1104/pp.103.030049 PubMed Abstract | CrossRef Full Text | Google Scholar Frungillo, L., Skelly, M. J., Loake, G. J., Spoel, S. H., and Salgado, I. (2014). S-nitrosothiols regulate nitric oxide production and storage in plants through the nitrogen assimilation pathway. Nat. Commun. 5:5401. doi: 10.1038/ncomms6401 PubMed Abstract | CrossRef Full Text | Google Scholar García-Mata, C., Gay, R., Sokolovski, S., Hills, A., Lamattina, L., and Blatt, M. R. (2003). Nitric oxide regulates K+ and Cl-channels in guard cells through a subset of abscisic acid-evoked signaling pathways. Proc. Natl. Acad. Sci. U.S.A. 100, 11116–11121. doi: 10.1073/pnas.1434381100 PubMed Abstract | CrossRef Full Text | Google Scholar García-Mata, C., and Lamattina, L. (2013). Gasotransmitters are emerging as new guard cell signaling molecules and regulators of leaf gas exchange. Plant Sci. 201-202, 66–73. doi: 10.3389/fpls.2016.00277 PubMed Abstract | CrossRef Full Text | Google Scholar Gregg, J., Jones, C., and Dawson, T. (2003). Urbanization effects on tree growth in the vicinity of New York City. Nature 424, 183–187. doi: 10.1038/nature01728 PubMed Abstract | CrossRef Full Text | Google Scholar Grill, E., Löffler, S., Winnacker, E. L., and Zenk, M. H. (1989). Phytochelatins, the heavy-metal-binding peptides of plants, are synthesized from glutathione by a specific gamma-glutamylcysteine dipeptidyl transpeptidase (phytochelatin synthase). Proc. Natl. Acad. Sci. U.S.A. 86, 6838–6842. doi: 10.1038/srep12329 PubMed Abstract | CrossRef Full Text | Google Scholar Gupta, K. J., and Igamberdiev, A. U. (2016). Reactive nitrogen species in mitochondria and their implications in plant energy status and hypoxic stress tolerance. Front. Plant Sci. 7:369. doi: 10.3389/fpls.2016.00369 PubMed Abstract | CrossRef Full Text | Google Scholar Hall, S., Huber, D., and Grimm, N. (2008). Soil N2O and NO emissions from an arid, urban ecosystem. J. Geophys. Res. 113:G01016. doi: 10.1029/2007JG000523 CrossRef Full Text | Google Scholar Hasanuzzaman, M., Nahar, K., Alam, M. M., Roychowdhury, R., and Fujita, M. (2013). Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants. Int. J. Mol. Sci. 14, 9643–9684. doi: 10.3390/ijms14059643 PubMed Abstract | CrossRef Full Text | Google Scholar Held, I., and Souden, B. (2000). Water vapor feedback and global warming. Annu. Rev. Energy Environ. 25, 441–475. doi: 10.1146/annurev.energy.25.1.441 CrossRef Full Text | Google Scholar Holzmeister, C., Gaupels, F., Geerlof, A., Sarioglu, H., Sattler, M., Durner, J., et al. (2015). Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration. J. Exp. Bot. 66, 989–999. doi: 10.1093/jxb/eru458 PubMed Abstract | CrossRef Full Text | Google Scholar IPCC (2014). Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, eds O. R. Edenhofer, Y. Pichs-Madruga, E. Sokona, S. Farahani, K. Kadner, A. Seyboth, et al. Cambridge: Cambridge University Press. Google Scholar Jeandroz, S., Wipf, D., Stuehr, D. J., Lamattina, L., Melkonian, M., Tian, Z., et al. (2016). Occurrence, structure, and evolution of nitric oxide synthase-like proteins in the plant kingdom. Sci. Signal. 9:re2. doi: 10.1126/scisignal.aad4403 PubMed Abstract | CrossRef Full Text | Google Scholar Jhun, I., Coull, B. A., Zanobetti, A., and Koutrakis, P. (2015). The impact of nitrogen oxides concentration decreases on ozone trends in the USA. Air Qual. Atmos. Health 8, 283–292. doi: 10.1088/1748-9326/10/8/084009 PubMed Abstract | CrossRef Full Text | Google Scholar Jin, C. W., Du, S. T., Chen, W. W., Li, G. X., Zhang, Y. S., and Zheng, S. J. (2009). Elevated carbon dioxide improves plants iron nutrition through enhancing the iron-deficiency-induced responses under iron-limited conditions in tomato. Plant Physiol. 150, 272–280. doi: 10.1104/pp.109.136721 PubMed Abstract | CrossRef Full Text | Google Scholar Karl, T. R., and Trenberth, K. E. (2003). Modern global climate change. Science 302, 1719–1723. doi: 10.1126/science.1090228 PubMed Abstract | CrossRef Full Text | Google Scholar Kiehl, J., and Trenberth, K. (1997). Earth’s annual global mean energy budget. Bull. Amer. Meteor. Soc. 78, 197–208. Google Scholar Kim, T., Böhmer, M., Hu, H., Nishimura, N., and Schroeder, J. I. (2010). Guard cell signal transduction network: advances in understanding abscisic acid, CO2, and Ca2+ signaling. Annu. Rev. Plant Biol. 61, 561–591. doi: 10.1146/annurev-arplant-042809-112226 PubMed Abstract | CrossRef Full Text | Google Scholar Kimball, B. (2016). Crop responses to elevated CO2 and interactions with H2O, N, and temperature. Curr. Opin. Plant Biol. 31, 36–43. doi: 10.1016/j.pbi.2016.03.006 PubMed Abstract | CrossRef Full Text | Google Scholar Königshofer, H., Tromballa, H. W., and Löppert, H. G. (2008). Early events in signaling high-temperature stress in tobacco BY2 cells involve alterations in membrane fluidity and enhanced hydrogen peroxide production. Plant Cell Environ. 31, 1771–1780. doi: 10.1111/j.1365-3040.2008.01880.x PubMed Abstract | CrossRef Full Text | Google Scholar Kumar, A., Castellano, I., Patti, F. P., Palumbo, A., and Buia, M. C. (2015). Nitric oxide in marine photosynthetic organisms. Nitric Oxide 47, 34–39. doi: 10.1038/srep12329 PubMed Abstract | CrossRef Full Text | Google Scholar Kumari, S., Agrawal, M., and Singh, A. (2015). Effects of ambient and elevated CO2 and ozone on physiological characteristics, antioxidative defense system and metabolites of potato in relation to ozone flux. Environ. Exp. Bot. 109, 276–287. doi: 10.1016/j.envexpbot.2014.06.015 CrossRef Full Text | Google Scholar Lamattina, L., García-Mata, C., Graziano, M., and Pagnussat, G. (2003). Nitric oxide: the versatility of an extensive signal molecule. Annu. Rev. Plant Biol. 54, 109–136. doi: 10.1146/annurev.arplant.54.031902.134752 PubMed Abstract | CrossRef Full Text | Google Scholar Laxalt, A. M., Beligni, M. V., and Lamattina, L. (1997). Nitric oxide preserves the level of chlorophyll in potato leaves infected by Phytophthora infestans. Eur. J. Plant Pathol. 103, 643–651. doi: 10.1023/A:1008604410875 CrossRef Full Text | Google Scholar Le Treut, H., Somerville, R., Cubasch, U., Ding, Y., Mauritzen, C., Mokssit, A., et al. (2007). “Historical overview of climate change science,” in Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, eds S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K. B. Averyt, et al. (Cambridge: Cambridge University Press). Google Scholar Leimu, R., Vergeer, P., Angeloni, F., and Ouborg, N. (2010). Habitat fragmentation, climate change, and inbreeding in plants. Ann. N. Y. Acad. Sci. 1195, 84–98. doi: 10.1111/j.1749-6632.2010.05450.x PubMed Abstract | CrossRef Full Text | Google Scholar Leitner, M., Vandelle, E., Gaupels, F., Bellin, D., and Delledonne, M. (2009). NO signals in the haze: nitric oxide signalling in plant defence. Curr. Opin. Plant Biol. 12, 451–458. doi: 10.1016/j.pbi.2009.05.012 PubMed Abstract | CrossRef Full Text | Google Scholar Long, S., Ainsworth, E., Leakey, A., Nösberger, J., and Ort, D. (2006). Food for thought: lower-than-expected crop yield stimulation with rising CO2 concentrations. Science 312, 1918–1921. doi: 10.1126/science.1114722 PubMed Abstract | CrossRef Full Text | Google Scholar Long, S., Ainsworth, E., Rogers, A., and Ort, D. (2004). Rising atmospheric carbon dioxide: plants FACE the future. Annu. Rev. Plant Biol. 55, 591–628. doi: 10.1146/annurev.arplant.55.031903.141610 PubMed Abstract | CrossRef Full Text | Google Scholar Lu, S., Su, W., Li, H., and Guo, Z. (2009). Abscisic acid improves drought tolerance of triploid bermudagrass and involves H2O2- and NO-induced antioxidant enzyme activities. Plant Physiol. Biochem. 7, 132–138. doi: 10.1016/j.plaphy.2008.10.006 PubMed Abstract | CrossRef Full Text | Google Scholar Marino, D., Dunand, C., Puppo, A., and Pauly, N. (2012). A burst of plant NADPH oxidases. Trends Plant Sci. 17, 9–15. doi: 10.1016/j.tplants.2011.10.001 PubMed Abstract | CrossRef Full Text | Google Scholar Markelz, R. J., Lai, L. X., Vosseler, L. N., and Leakey, A. D. (2014). Transcriptional reprogramming and stimulation of leaf respiration by elevated CO2 concentration is diminished, but not eliminated, under limiting nitrogen supply. Plant Cell Environ. 37, 886–988. doi: 10.1111/pce.12205 PubMed Abstract | CrossRef Full Text | Google Scholar McAdam, E. L., Brodribb, T. J., and McAdam, S. A. (2017). Does ozone increase ABA levels by non-enzymatic synthesis causing stomata to close? Plant Cell Environ. 40, 741–747. doi: 10.1111/pce.12893 PubMed Abstract | CrossRef Full Text | Google Scholar Medinets, S., Skiba, U., Rennenberg, H., and Butterbach-Bahl, K. (2015). A review of soil NO transformation: associated processes and possible physiological significance on organisms. Soil Biol. Biochem. 80, 92–117. doi: 10.1016/j.soilbio.2014.09.025 CrossRef Full Text | Google Scholar Meyer, C., Lea, U. S., Provan, F., Kaiser, W. M., and Lillo, C. (2005). Is nitrate reductase a major player in the plant NO (nitric oxide) game? Photosynth. Res. 83, 181–189. doi: 10.1016/j.tplants.2011.10.001 PubMed Abstract | CrossRef Full Text | Google Scholar Mittler, R., and Blumwald, E. (2010). Genetic engineering for modern agriculture: challenges and perspectives. Annu. Rev. Plant Biol. 61, 443–462. doi: 10.1146/annurev-arplant-042809-112116 PubMed Abstract | CrossRef Full Text | Google Scholar Mur, L. A., Kenton, P., Lloyd, A. J., Ougham, H., and Prats, E. (2008). The hypersensitive response; the centenary is upon us but how much do we know? J. Exp. Bot. 59, 501–520. doi: 10.1093/jxb/erm239 PubMed Abstract | CrossRef Full Text | Google Scholar Nicotra, A., Atkin, O., Bonser, S., Davidson, A., Finnegan, E., Mathesius, U., et al. (2010). Plant phenotypic plasticity in a changing climate. Trends Plant Sci. 15, 684–692. doi: 10.1016/j.tplants.2010.09.008 PubMed Abstract | CrossRef Full Text | Google Scholar Ortega-Galisteo, A. P., Rodríguez-Serrano, M., Pazmiño, D. M., Gupta, D. K., Sandalio, L. M., and Romero-Puertas, M. C. (2012). S-Nitrosylated proteins in pea (Pisum sativum L.) leaf peroxisomes: changes under abiotic stress. J. Exp. Bot. 63, 2089–2103. doi: 10.1016/j.tplants.2011.10.001 PubMed Abstract | CrossRef Full Text | Google Scholar Pilegaard, K. (2013). Processes regulating nitric oxide emissions from soils. Philos. Trans. R. Soc. Lond. B Biol. Sci. 368:20130126. doi: 10.1098/rstb.2013.0126 PubMed Abstract | CrossRef Full Text | Google Scholar Qu, A. L., Ding, Y. F., Jiang, Q., and Zhu, C. (2013). Molecular mechanisms of the plant heat stress response. Biochem. Biophys. Res. Commun. 432, 203–207. doi: 10.1016/j.bbrc.2013.01.104 PubMed Abstract | CrossRef Full Text | Google Scholar Rockel, P., Strube, F., Rockel, A., Wildt, J., and Kaiser, W. M. (2002). Regulation of nitric oxide (NO) production by plant nitrate reductase in vivo and in vitro. J. Exp. Bot. 53, 103–110. doi: 10.1093/jexbot/53.366.103 CrossRef Full Text | Google Scholar Roelfsema, M. R., Hedrich, R., and Geiger, D. (2012). Anion channels: master switches of stress responses. Trends Plant Sci. 17, 221–229. doi: 10.1016/j.tplants.2012.01.009 PubMed Abstract | CrossRef Full Text | Google Scholar Romero-Puertas, M. C., Campostrini, N., Mattè, A., Righetti, P. G., Perazzolli, M., Zolla, L., et al. (2008). Proteomic analysis of S-nitrosylated proteins in Arabidopsis thaliana undergoing hypersensitive response. Proteomics 8, 1459–1469. doi: 10.1002/pmic.200700536 PubMed Abstract | CrossRef Full Text | Google Scholar Romero-Puertas, M. C., Laxa, M., Mattè, A., Zaninotto, F., Finkemeier, I., Jones, A. M. E., et al. (2007). S-nitrosylation of peroxiredoxin II E promotes peroxynitrite-mediated tyrosine nitration. Plant Cell 19, 4120–4130. doi: 10.1105/tpc.107.055061 PubMed Abstract | CrossRef Full Text | Google Scholar Rouhier, N., Lemaire, S. D., and Jacquot, J.-P. (2008). The role of glutathione in photosynthetic organisms: emerging functions for glutaredoxins and glutathionylation. Annu. Rev. Plant Biol. 59, 143–166. doi: 10.1146/annurev.arplant.59.032607.092811 PubMed Abstract | CrossRef Full Text | Google Scholar Santa-Cruz, D., Pacienza, N., Zilli, C., Tomaro, M., Balestrasse, K., and Yannarelli, G. (2014). Nitric oxide induces specific isoforms of antioxidant enzymes in soybean leaves subjected to enhanced ultraviolet-B radiation. J. Photochem. Photobiol. B 141, 202–209. doi: 10.1016/j.jphotobiol.2014.09.019 PubMed Abstract | CrossRef Full Text | Google Scholar Scheffers, B. R., De Meester, L., Bridge, T. C., Hoffmann, A. A., Pandolfi, J. M., Corlett, R. T., et al. (2016). The broad footprint of climate change from genes to biomes to people. Science 354:aaf7671. doi: 10.1126/science.aaf7671 PubMed Abstract | CrossRef Full Text | Google Scholar Schmidt, G. A., Ruedy, R. A., Miller, R. L., and Lacis, A. A. (2010). Attribution of the present-day total greenhouse effect. J. Geophys. Res. 115:D20106. doi: 10.1029/2010JD014287 CrossRef Full Text | Google Scholar Shi, K., Li, X., Zhang, H., Zhang, G., Liu, Y., Zhou, Y., et al. (2015). Guard cell hydrogen peroxide and nitric oxide mediate elevated CO2-induced stomatali movement in tomato. New Phytol. 208, 342–353. doi: 10.1111/nph.13621 PubMed Abstract | CrossRef Full Text | Google Scholar Shi, Q., Ding, F., Wang, X., and Wei, M. (2007). Exogenous nitric oxide protect cucumber roots against oxidative stress induced by salt stress. Plant Physiol. Biochem. 45, 542–550. doi: 10.1016/j.plaphy.2007.05.005 PubMed Abstract | CrossRef Full Text | Google Scholar Shi, S., Wang, G., Wang, Y., Zhang, L., and Zhang, L. (2005). Protective effect of nitric oxide against oxidative stress under ultraviolet-B radiation. Nitric Oxide 13, 1–9. doi: 10.1016/j.niox.2005.04.006 PubMed Abstract | CrossRef Full Text | Google Scholar Singh, R., Hogg, N., Goss, S., Antholine, W., and Kalyanaraman, B. (1999). Mechanism of superoxide dismutase/H2O2-mediated nitric oxide release from S-nitrosoglutathione–role of glutamate. Arch. Biochem. Biophys. 372, 8–15. doi: 10.1006/abbi.1999.1447 PubMed Abstract | CrossRef Full Text | Google Scholar Smith, N. G., and Dukes, J. S. (2013). Plant respiration and photosynthesis in global-scale models: incorporating acclimation to temperature and CO2. Glob. Change Biol. 19, 45–63. doi: 10.1111/j.1365-2486.2012.02797.x PubMed Abstract | CrossRef Full Text | Google Scholar Soden, B. J., Jackson, D. L., Ramaswamy, V., Schwarzkopf, M. D., and Huang, X. (2005). The radiative signature of upper tropospheric moistening. Science 310, 841–844. doi: 10.1126/science.1115602 PubMed Abstract | CrossRef Full Text | Google Scholar Song, L., Ding, W., Zhao, M., Sun, B., and Zhang, L. (2006). Nitric oxide protects against oxidative stress under heat stress in the calluses from two ecotypes of reed. Plant Sci. 171, 449–458. doi: 10.1016/j.plantsci.2006.05.002 PubMed Abstract | CrossRef Full Text | Google Scholar Song, Y., Miao, Y., and Song, C. P. (2014). Behind the scenes: the roles of reactive oxygen species in guard cells. New Phytol. 201, 1121–1140. doi: 10.1111/nph.12565 PubMed Abstract | CrossRef Full Text | Google Scholar Stockwell, C., Hendry, A., and Kinnison, M. (2003). Contemporary evolution meets conservation. Trends Ecol. Evol. 18, 94–101. doi: 10.1016/S0169-5347(02)00044-7 CrossRef Full Text | Google Scholar Tossi, V., Lamattina, L., and Cassia, R. (2009). An increase in the concentration of abscisic acid is critical for nitric oxide-mediated plant adaptive responses to UV-B irradiation. New Phytol. 181, 871–879. doi: 10.1111/j.1469-8137.2008.02722.x PubMed Abstract | CrossRef Full Text | Google Scholar Uchida, A., Jagendorf, A. T., Hibino, T., Takabe, T., and Takabe, T. (2002). Effects of hydrogen peroxide and nitric oxide on both salt and heat stress tolerance in rice. Plant Sci. 163, 515–523. doi: 10.1016/S0168-9452(02)00159-0 CrossRef Full Text | Google Scholar Vainonen, J. P., and Kangasjärvi, J. (2015). Plant signalling in acute ozone exposure. Plant Cell Environ. 38, 240–252. doi: 10.1111/pce.12273 PubMed Abstract | CrossRef Full Text | Google Scholar Voesenek, L. A., and Bailey-Serres, J. (2015). Flood adaptive traits and processes: an overview. New Phytol. 206, 57–73. doi: 10.1111/nph.13209 PubMed Abstract | CrossRef Full Text | Google Scholar Wang, H., Xiao, W., Niu, Y., Chai, R., Jin, C., and Zhang, Y. (2015). Elevated carbon dioxide induces stomatal closure of Arabidopsis thaliana (L.) heynh. through an increased production of nitric oxide. J. Plant Growth Regul. 34, 372–380. doi: 10.1007/s00344-014-9473-6 CrossRef Full Text | Google Scholar Wuebbles, D. J., and Hayhoe, K. (2002). Atmospheric methane and global change. Earth Sci. Rev. 57, 177–210. doi: 10.1016/S0012-8252(01)00062-9 CrossRef Full Text | Google Scholar Xie, Y., Mao, Y., Zhang, W., Lai, D., Wang, Q., and Shen, W. (2014). Reactive oxygen species-dependent nitric oxide production contributes to hydrogen-promoted stomatal closure in Arabidopsis. Plant Physiol. 165, 759–773. doi: 10.1104/pp.114.237925 PubMed Abstract | CrossRef Full Text | Google Scholar Xu, Z., Jiang, Y., Jia, B., and Zhou, G. (2016). Elevated-CO2 response of stomata and its dependence on environmental factors. Front. Plant Sci. 7:657. doi: 10.3389/fpls.2016.00657 PubMed Abstract | CrossRef Full Text | Google Scholar Xu, Z., Jiang, Y., and Zhou, G. (2015). Response and adaptation of photosynthesis, respiration, and antioxidant systems to elevated CO2 with environmental stress in plants. Front. Plant Sci. 6:701. doi: 10.3389/fpls.2015.00701 PubMed Abstract | CrossRef Full Text | Google Scholar Xue, L., Li, S., Sheng, H., Feng, H., Xu, S., and An, L. (2007). Nitric oxide alleviates oxidative damage induced by enhanced ultraviolet-B radiation in cyanobacterium. Curr. Microbiol. 55, 294–301. doi: 10.1007/s00284-006-0621-5 PubMed Abstract | CrossRef Full Text | Google Scholar Yan, W., Zhong, Y., and Shangguan, Z. (2017). Contrasting responses of leaf stomatal characteristics to climate change: a considerable challenge to predict carbon and water cycles. Glob. Chang. Biol. 23, 3781–3793. doi: 10.1111/gcb.13654 PubMed Abstract | CrossRef Full Text | Google Scholar Yang, H., Mu, J., Chen, L., Feng, J., Hu, J., Li, L., et al. (2015). S -Nitrosylation positively regulates ascorbate peroxidase activity during plant stress responses. Plant Physiol. 167, 1604–1615. doi: 10.1104/pp.114.255216 PubMed Abstract | CrossRef Full Text | Google Scholar Yun, B.-W., Feechan, A., Yin, M., Saidi, N. B., Le Bihan, T., Yu, M., et al. (2011). S-nitrosylation of NADPH oxidase regulates cell death in plant immunity. Nature 478, 264–268. doi: 10.1038/nature10427 PubMed Abstract | CrossRef Full Text | Google Scholar Zhang, Y., Tan, J., Guo, Z., Lu, S., He, S., Shu, W., et al. (2009). Increased abscisic acid levels in transgenic tobacco over-expressing 9 cis-epoxycarotenoid dioxygenase influence H2O2 and NO production and antioxidant defenses. Plant Cell Environ. 32, 509–519. doi: 10.1111/j.1365-3040.2009.01945.x PubMed Abstract | CrossRef Full Text | Google Scholar Zinta, G., AbdElgawad, H., Domagalska, M. A., Vergauwen, L., Knapen, D., Nijs, I., et al. (2014). Physiological, biochemical, and genome-wide transcriptional analysis reveals that elevated CO2 mitigates the impact of combined heat wave and drought stress in Arabidopsis thaliana at multiple organizational levels. Glob. Chang. Biol. 20, 3670–3685. doi: 10.1111/gcb.12626 PubMed Abstract | CrossRef Full Text | Google Scholar Keywords: climate change, greenhouse effect, oxidative stress, nitric oxide, plants Citation: Cassia R, Nocioni M, Correa-Aragunde N and Lamattina L (2018) Climate Change and the Impact of Greenhouse Gasses: CO2 and NO, Friends and Foes of Plant Oxidative Stress. Front. Plant Sci. 9:273. doi: 10.3389/fpls.2018.00273 Received: 18 November 2017; Accepted: 16 February 2018;Published: 01 March 2018. Edited by: Luisa M. Sandalio, Consejo Superior de Investigaciones Científicas (CSIC), Spain Reviewed by: María C. Romero-Puertas, Consejo Superior de Investigaciones Científicas (CSIC), Spain Diana Bellin, University of Verona, Italy Copyright © 2018 Cassia, Nocioni, Correa-Aragunde and Lamattina. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. *Correspondence: Raúl Cassia, [email protected] COMMENTARY ORIGINAL ARTICLE People also looked at Suggest a Research Topic >
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                            [body] => MSU Extension Greenhouse gases: Their impact on climate change Terry Gibb, Michigan State University Extension - December 21, 2015 Tweet Print Email Many scientists are predicting the Earth is heading toward a global warming danger zone and humans are responsible for most of it by upsetting the balance in the natural ecosystem. Climate change has been debated for a while on whether it’s real or a myth. With the signing of the Paris climate agreement this month, it appears that everyone finally agrees it’s real and we need start working on it before the planet reaches the danger zone from where it can’t recover. But what is causing most of this climate change? In a word: Humans, or more precisely, the human actions that increase greenhouse gas emissions. How does burning coal, driving our cars and cutting down trees for development result in melting glaciers, rising water levels and warmer water temperatures? Greenhouse gases are gases in the Earth's atmosphere that produce the greenhouse effect. Changes in the concentration of certain greenhouse gases, from human activity (such as burning fossil fuels), increase the risk of global climate change. Greenhouse gases include water vapor, carbon dioxide (CO2), methane, nitrous oxide, halogenated fluorocarbons, ozone, perfluorinated carbons, and hydro fluorocarbons.  These gases surround and insulate the Earth like a blanket. They allow the sun to reach and warm the Earth’s surface then block the warmth from escaping back into space. Human activities, including those mentioned above, have continued to increase and have upset the balance of the natural system for several greenhouse gases: methane, nitrous oxide, fluorinated gases and especially carbon dioxide. As these gases continue to be emitted into the atmosphere, they form a thicker layer. And just like the blanket, the thicker it is, the more heat it holds. The United States and China are the biggest contributors of these gases with the European Union coming in third. The major culprit of gas emissions is the burning of fossil fuels (coal, oil and natural gas). Other pollution activities include agriculture, deforestation and livestock breeding. Carbon dioxide is the biggest contributor to the problem. It occurs naturally from a number of sources. In the natural system, CO2 can be absorbed by oceans and plants taking it in during photosynthesis. The man made increases of CO2 have tipped the balance and these natural intake sources cannot absorb these additional amounts. Some CO2 can remain in the atmosphere for thousands of year. Even if the oceans could absorb more CO2 from the atmosphere, it increases the acidity of the oceans and turns it into carbonic acid. This acid uses up the carbonate in the water so it’s not available for sea creatures who need it for skeleton and shell building and coral reefs. Methane is the second largest culprit of the greenhouse gases. In addition to the same industrial sources that emit CO2, landfills and rice cultivation are additional sources of methane gas. While methane does not last as long in the atmosphere as CO2, it is much better at trapping heat. Nitrous oxide (N2O), another greenhouse gas, is part of the Earth’s nitrogen cycle. Unfortunately 40 percent of the nitrous oxide worldwide comes from human activities, including fossil fuel burning, agriculture and wastewater management. It can last in the atmosphere approximately 114 years before it is removed or destroyed by chemical reaction. According the U.S. EPA, “the impact of 1 pound of N2O on warming the atmosphere is almost 300 times that of 1 pound of carbon dioxide.” Since weather information has been accurately recorded, the temperature trend has been increasing. For example, the ten warmest years on record have occurred since 1998 and so far 2015 is the hottest year on record and with only a few weeks left in the year, it should end that way. Unfortunately, it appears the blanket is doing its job. For more information on the Paris agreement, see the Michigan State University Extension news article “Paris climate agreement” For more information on greenhouse gases, visit the U.S. EPA website.  This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464). Did you find this article useful? Please tell us why Submit climate changeclimate change and variabilitycommunityenergyforestrygovernmentmsu extensionnatural resourcespublic policy Join the MSU Forestry Community! Apply Today Check out the Forestry B.S. program! Learn More You Might Also Be Interested In. Paris climate agreement. Extension will be key partner in USDA climate hubs. Celebrating 100 years of Michigan State University Extension in Alcona County. Marquette Area Climate and Health Adaptation Guidebook - Volume III: Prioritizing and Implementing Recommendations. Should local governments regulate outdoor wood boilers? – Part 2. Sources of Information for Forest Products Exporting (E2616). Close « Previous Next » Search Menu View information by type. Articles Classes Events People Podcasts Publications Recipes Videos MSU Extension .
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                            [body] => Climate Basics » Climate Science Share Main Greenhouse Gases. Main Greenhouse Gases. Multiple gases contribute to the greenhouse effect that sets Earth’s temperature over geologic time. Small changes in the atmospheric concentration of these gases can lead to changes in temperature that make the difference between ice ages when mastodons roamed the Earth, and the sweltering heat in which the dinosaurs lived. Two characteristics of atmospheric gases determine the strength of their greenhouse effect. The first is their ability to absorb energy and radiate it (their “radiative efficiency”).  The second is the atmospheric lifetime, which measures how long the gas stays in the atmosphere before natural processes (e.g., chemical reactions) remove it. These characteristics are incorporated in the Global Warming Potential (GWP), a measure of the radiative effect (i.e. the strength of their greenhouse effect) of each unit of gas (by weight) over a specified period of time, expressed relative to the radiative effect of carbon dioxide (CO2). This is often calculated over 100 years, though it can be done for any time period. Gases with high GWPs will warm the Earth more than an equal amount of CO2 over the same time period. A gas with a long lifetime, but relatively low radiative efficiency, may end up exerting more warming influence than a gas that leaves the atmosphere faster than the time window of interest but has a comparatively high radiative efficiency, and this would be reflected in a higher GWP. The table below presents atmospheric lifetime and GWP values for major greenhouse gases from the Fifth IPCC Assessment Report (AR5) released in 2014. These values are periodically updated by the scientific community as new research refines estimates of radiative properties and atmospheric removal mechanisms (sinks) for each gas. Despite carbon dioxide’s comparatively low GWP among major greenhouse gases, the large human-caused increase in its atmospheric concentration has caused the majority of global warming. Likewise, methane is responsible for a large portion of recent warming despite having a GWP much lower than several other greenhouse gases because emissions have increased drastically. Source Fifth Assessment Report (Intergovernmental Panel on Climate Change, 2014). Greenhouse gas Chemical formula Global Warming Potential, 100-year time horizon Atmospheric Lifetime (years) Global Warming Potential and Atmospheric Lifetime for Major Greenhouse Gases Carbon Dioxide CO2 1 100* Methane CH4 25 12 Nitrous Oxide N2O 265 121 Chlorofluorocarbon-12 (CFC-12) CCl2F2 10,200 100 Hydrofluorocarbon-23 (HFC-23) CHF3 12,400 222 Sulfur Hexafluoride SF6 23,500 3,200 Nitrogen Trifluoride NF3 16,100 500 * No single lifetime can be given for carbon dioxide because it moves throughout the earth system at differing rates. Some carbon dioxide will be absorbed very quickly, while some will remain in the atmosphere for thousands of years. The table below shows the relative concentrations of these major greenhouse gases and their sources. Some gases (like CO2) are made by both natural and manmade processes, while others (like hydrofluorocarbons) are only the result of human industrial activity. CO2 is typically measured in parts per million because it is 1,000 times more prevalent than the other gases, but is shown as parts per billion in the table for consistency. Notes Atmospheric concentrations are all shown in parts per billion (ppb). Source Fifth Assessment Report (Intergovernmental Panel on Climate Change IPCC, 2014) Greenhouse gas Major sources Pre-industrial concentration (ppb) 2011 concentration (ppb) Sources and Concentrations of Major Greenhouse Gases Carbon Dioxide Fossil fuel combustion; Deforestation; Cement production 278,000 390,000 Methane Fossil fuel production; Agriculture; Landfills 722 1,803 Nitrous Oxide Fertilizer application; Fossil fuel and biomass combustion; Industrial processes 271 324 Chlorofluorocarbon-12 (CFC-12) Refrigerants 0 0.527 Hydrofluorocarbon-23 (HFC-23) Refrigerants 0 0.024 Sulfur Hexafluoride Electricity transmission 0 0.0073 Nitrogen Trifluoride Semiconductor manufacturing 0 0.00086 The Rise of Atmospheric Carbon Dioxide. Notes This figure shows the monthly mean carbon dioxide measurements at the Mauna Loa Observatory in Hawaii since 1958. The red line shows the monthly mean while the black line shows the same after correcting for the average seasonal cycle. The small up and down saw-tooth pattern reflects seasonal changes in the release and uptake of carbon dioxide by plants. Source Source: Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends) and Dr. Ralph Keeling, Scripps Institution of Oceanography (scrippsco2.ucsd.edu).   *Carbon dioxide is quite stable in Earth’s atmosphere, but individual carbon dioxide molecules are in near constant flux from difference reservoirs, such as the surface ocean, land biota, and the atmosphere. A commonly used estimate for CO2 lifetime is 100 years, but this really only reflects the lifetime of a portion of the atmospheric carbon dioxide reservoir. Some portion has a lifetime of up to 1,000 years (IPCC 2007, FAQs). Related Content. Press Release Nat Keohane on the IPCC Working Group I findings August 9, 2021 Tags View Climate Science Q&A Tags ScienceExtreme Weather View Short-lived Climate Pollutants Tags ScienceEmissionsMontreal ProtocolEnergy View Load More ✕
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                            [description] => climate change - climate change - Greenhouse gases: Greenhouse gases are gas molecules that have the property of absorbing infrared radiation (net heat energy) emitted from Earth’s surface and reradiating it back to Earth’s surface, thus contributing to the phenomenon known as the greenhouse effect. Carbon dioxide, methane, and water vapour are the most important greenhouse gases, and they have a profound effect on the energy budget of the Earth system despite making up only a fraction of all atmospheric gases. Concentrations of greenhouse gases have varied substantially during Earth’s history, and these variations have driven substantial climate changes at a wide range of timescales. In general, greenhouse
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                            [body] => Greenhouse gases Greenhouse gases are gas molecules that have the property of absorbing infrared radiation (net heat energy) emitted from Earth’s surface and reradiating it back to Earth’s surface, thus contributing to the phenomenon known as the greenhouse effect. Carbon dioxide, methane, and water vapour are the most important greenhouse gases, and they have a profound effect on the energy budget of the Earth system despite making up only a fraction of all atmospheric gases. Concentrations of greenhouse gases have varied substantially during Earth’s history, and these variations have driven substantial climate changes at a wide range of timescales. In general, greenhouse gas concentrations have been particularly high during warm periods and low during cold phases. A number of processes influence greenhouse gas concentrations. Some, such as tectonic activities, operate at timescales of millions of years, whereas others, such as vegetation, soil, wetland, and ocean sources and sinks, operate at timescales of hundreds to thousands of years. Human activities—especially fossil-fuel combustion since the Industrial Revolution—are responsible for steady increases in atmospheric concentrations of various greenhouse gases, especially carbon dioxide, methane, ozone, and chlorofluorocarbons (CFCs).greenhouse effect on EarthThe greenhouse effect on Earth. Some incoming sunlight is reflected by Earth's atmosphere and surface, but most is absorbed by the surface, which is warmed. Infrared (IR) radiation is then emitted from the surface. Some IR radiation escapes to space, but some is absorbed by the atmosphere's greenhouse gases (especially water vapour, carbon dioxide, and methane) and reradiated in all directions, some to space and some back toward the surface, where it further warms the surface and the lower atmosphere.Encyclopædia Britannica, Inc. Feedback. Perhaps the most intensively discussed and researched topic in climate variability is the role of interactions and feedbacks among the various components of the Earth system. The feedbacks involve different components that operate at different rates and timescales. Ice sheets, sea ice, terrestrial vegetation, ocean temperatures, weathering rates, ocean circulation, and greenhouse gas concentrations are all influenced either directly or indirectly by the atmosphere; however, they also all feed back into the atmosphere, thereby influencing it in important ways. For example, different forms and densities of vegetation on the land surface influence the albedo, or reflectivity, of Earth’s surface, thus affecting the overall radiation budget at local to regional scales. At the same time, the transfer of water molecules from soil to the atmosphere is mediated by vegetation, both directly (from transpiration through plant stomata) and indirectly (from shading and temperature influences on direct evaporation from soil). This regulation of latent heat flux by vegetation can influence climate at local to global scales. As a result, changes in vegetation, which are partially controlled by climate, can in turn influence the climate system. Vegetation also influences greenhouse gas concentrations; living plants constitute an important sink for atmospheric carbon dioxide, whereas they act as sources of carbon dioxide when they are burned by wildfires or undergo decomposition. These and other feedbacks among the various components of the Earth system are critical for both understanding past climate changes and predicting future ones.Adirondack MountainsMixed evergreen and hardwood forest on the slopes of the Adirondack Mountains near Keene Valley, New York.Jerome WyckoffalbedoSurface reflectance (albedo) of solar energy under different patterns of land use. (Left) In a preagricultural landscape, large forest-covered areas of low surface albedo alternate with large open areas of high albedo. (Right) In an agricultural landscape, a patchwork of smaller forested and open areas exists, each with its characteristic albedo.Encyclopædia Britannica, Inc. Britannica Quiz Winter Weather Quiz Winter is a time of extreme weather and unusual words to describe that weather. These quiz questions, courtesy of Merriam-Webster, will make you yearn for summer. Human activities. Recognition of global climate change as an environmental issue has drawn attention to the climatic impact of human activities. Most of this attention has focused on carbon dioxide emission via fossil-fuel combustion and deforestation. Human activities also yield releases of other greenhouse gases, such as methane (from rice cultivation, livestock, landfills, and other sources) and chlorofluorocarbons (from industrial sources). There is little doubt among climatologists that these greenhouse gases affect the radiation budget of Earth; the nature and magnitude of the climatic response are a subject of intense research activity. Paleoclimate records from tree rings, coral, and ice cores indicate a clear warming trend spanning the entire 20th century and the first decade of the 21st century. In fact, the 20th century was the warmest of the past 10 centuries, and the decade 2011–20 was the warmest decade since the beginning of modern instrumental record keeping. Many climatologists have pointed to this warming pattern as clear evidence of human-induced climate change resulting from the production of greenhouse gases.decline in Arctic sea-ice coverageSea-ice loss in the Arctic since the end of the 20th century has lowered the region's albedo (that is, fraction of light that is reflected by a body or surface), decreasing the region's ability to reflect incoming sunlight while increasing its ability to absorb energy from sunlight.Encyclopædia Britannica, Inc./Kenny Chmielewski A second type of human impact, the conversion of vegetation by deforestation, afforestation, and agriculture, is receiving mounting attention as a further source of climate change. It is becoming increasingly clear that human impacts on vegetation cover can have local, regional, and even global effects on climate, due to changes in the sensible and latent heat flux to the atmosphere and the distribution of energy within the climate system. The extent to which these factors contribute to recent and ongoing climate change is an important, emerging area of study.tropical forests and deforestationTropical forests and deforestation in the early 21st century.Encyclopædia Britannica, Inc. Load Next Page
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                            [title] => Greenhouse effect | Climate Change Connection
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                            [h1] => Climate changeGreenhouse effect and climate change: scientific basis and overview
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                                                    [text] => https://doi.org/10.1016/0960-1481(93)90108-S
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                            [body] => Climate changeGreenhouse effect and climate change: scientific basis and overviewAuthor links open overlay panelP.C.JainShow moreShareCitehttps://doi.org/10.1016/0960-1481(93)90108-SGet rights and contentAbstract. Climate change due to ‘enhanced greenhouse effect’, arising as a result of human activities is considered a major global environmental threat to mankind. A review of the topic including the physics of the greenhouse effect is given. The Earth provides a unique life-supporting environment. Solar radiation has been responsible for maintaining the Earth's climatic system, the biosphere and fuelling the present technological age. Earth's temperature is a result of the equilibrium between the solar energy absorbed by the Earth and the long wave (infra-red) radiation from the Earth escaping into space. The natural greenhouse effect arises due to some of the trace gases, called the greenhouse gases, which are nearly transparent to solar radiation but strongly absorb the infra-red radiation emitted by the Earth. This results in a warming of the Earth by about 30°C and makes it habitable. Since industrialization, human activities have resulted in steadily increasing concentrations of the greenhouse gases—carbon dioxide, methane, nitrous oxide and chlorofluorocarbons—in the atmosphere, leading to fears of the ‘enhanced greenhouse effect’. Carbon dixoide alone contributes roughly two-thirds to the ‘enhanced greenhouse effect’.Past records suggest that the Earth has warmed by 0.5°C and the global sea level has increased by 15 cm since the beginning of this century. Climate models predict a further warming of 0.3°C per decade if no efforts are made to decrease emissions of greenhouse gases. This warming rate is higher than that at any time during the past 10 000 years and is likely to cause global changes in agricultural patterns, precipitation, water resources, rise in sea levels and inundation of coastal areas, occurrence of more frequent and intense extreme events such as droughts and hurricanes. African nations will be particularly vulnerable to some of these changes. Uncertainties do remain in the predictions of climate change at regional level and the scale and timing of such changes.Limitation and adaptation strategies need to be developed and implemented. Decreasing use of fossil fuels and increasing use of alternative sources of energy—solar, wind, hydro, biomass—coupled with energy conservation strategies are needed to reduce emissions of greenhouse gases. Reducing deforestation and embarking on reforestation programs is needed to increase the sinks of carbon dioxide. More research is needed to enable better understanding of climate processes and decrease uncertainties in climate predictions. Climate data, analyses and information need to be utilised in planning processes.Previous article in issueNext article in issueRecommended articlesCiting articles (0)View full textCopyright © 1993 Published by Elsevier Ltd.
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                            [title] => Fossil fuels and climate change: the facts | ClientEarth
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                            [body] => Fossil fuels and climate change: the facts Fossil fuel companies spend millions on glossy ad campaigns about clean energy, while they continue to increase production of oil and gas, which release emissions that have a devastating impact on our planet. The science is clear – we’re in a climate emergency that fossil fuels are helping to create. Here are the facts:What are fossil fuels?Fossil fuels are formed from the decomposition of buried carbon-based organisms that died millions of years ago. They create carbon-rich deposits that are extracted and burned for energy. They are non-renewable and currently supply around 80% of the world’s energy. They are also used to make plastic, steel and a huge range of products. There are three types of fossil fuel – coal, oil and gas.Learn more about our work moving beyond fossil fuels What is the impact of fossil fuels on our planet?When fossil fuels are burned, they release large amounts of carbon dioxide, a greenhouse gas, into the air. Greenhouse gases trap heat in our atmosphere, causing global warming. Already the average global temperature has increased by 1C. Warming above 1.5°C risks further sea level rise, extreme weather, biodiversity loss and species extinction, as well as food scarcity, worsening health and poverty for millions of people worldwide.Subscribe to our emails and join the fight to protect life on EarthHow big is the impact of fossil fuels on climate change and our planet?The Intergovernmental Panel on Climate Change (IPCC) has found that emissions from fossil fuels are the dominant cause of global warming. In 2018, 89% of global CO2 emissions came from fossil fuels and industry.Coal is the dirtiest of the fossil fuels and responsible for over 0.3C of the 1C increase in global average temperatures – making it the single largest source of global temperature rise.Oil releases a huge amount of carbon when burned - approximately a third of the world’s total carbon emissions. There have also been a number of oil spills in recent years that have a devastating impact on our ocean’s ecosystem.Natural gas is often promoted as a cleaner energy source than coal and oil. However, it is still a fossil fuel and accounts for a fifth of the world’s total carbon emissions.Can we continue to burn fossil fuels?The IPCC warns that fossil fuel emissions must be halved within 11 years if global warming is to be limited to 1.5°C above pre-industrial levels.In 2015, the world’s governments signed up to the Paris Agreement committing to reduce carbon emissions. However, a recent report by the UN Environment Programme shows that globally, we are on track to produce more than double the amount of coal, oil and gas by 2030 than we can burn if we are to limit global warming by 1.5C. So more needs to be done.What’s the role of fossil fuel companies in the future of our planet?Fossil fuel companies remain huge polluters, producing and selling fossil fuel products while scientists say we need a mass switch to renewable energy and efficiency. In 2019, BP spent millions on an advertising campaign about its low-carbon energy and cleaner natural gas. While its advertising focused on clean energy, in reality, more than 96% of BP’s annual expenditure is still on oil and gas. And it is definitely not just BP – it’s an industry-wide problem.That’s why, in December of 2019, we lodged a complaint with the UK National Contact Point about BP’s adverts. We also launched a campaign calling for a ban on fossil fuel advertising unless it comes with a tobacco-style health warning. Because the public should know the whole truth about fossil fuels.In February 2020, BP withdrew its advertisements and its CEO Bernard Looney said they would not be replaced under the company’s new policy promising an end to ‘corporate reputation advertising’. He also committed BP to redirecting its advertising resources towards advocating for progressive climate policies.Read the Greenwashing Files to uncover the truth behind fossil fuel company greenwashingMore to explore. Clean energyEUClimate24 June 2020Replacing fossil fuels with green energy Fossil fuelsPlasticsEUClimate10 June 2020Big Oil's Plan B: Plastic ClimateFossil fuels16 May 2019Coal in Europe: it's time to stop diggingWe use cookies to personalise content and ads, to provide social media features and to analyse our traffic. You can read our privacy policy here.Click 'Continue' if you consent to use all non-essential cookies.Continue
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                            [body] => Carbon Dioxide, Methane, Nitrous Oxide, and the Greenhouse Effect Home » Get Started » Learn » Carbon Dioxide, Methane, Nitrous Oxide, and the Greenhouse Effect The greenhouse effect is a natural process where atmospheric gases trap heat – a phenomena that allows the Earth to retain enough solar heat to be livable. Without the greenhouse effect, the Earth would not support most forms of life. How Does the Greenhouse Effect Work? Although the process is complex, the greenhouse effect can be described fairly simply: Sunlight passes through the atmosphere. Clouds, ice caps and other light-colored surfaces reflect some light back into space, but most of the incoming energy reaches the planet’s surface. The Earth radiates heat back toward space. Greenhouse gases in the atmosphere absorb that heat, bouncing some back to the Earth’s surface and releasing some into the atmosphere. Greater concentrations of greenhouse gases mean more solar radiation is trapped within the Earth’s atmosphere, making temperatures rise. Source: W. Elder, NPS. What are Greenhouse Gases? Greenhouse gases include carbon dioxide, methane, nitrous oxide and other gases that accumulate in the atmosphere and create the heat-reflective layer that keeps the Earth at a livable temperature. These gases form the insulation that keeps the planet warm enough to support life. Some of the most common — and worrisome — greenhouse gases are: Carbon dioxide, which is emitted whenever coal, oil, natural gas and other carbon-rich fossil fuels are burned. Although carbon dioxide is not the most powerful greenhouse gas, it is the largest contributor to climate change because it is so common. In order to reduce carbon dioxide emissions, we need to reduce the amount of fuel we use in our cars, homes, and lives. Methane is caused by the decomposition of plant matter, and is released from landfills, swamps, rice paddies. Cattle also release methane. Although methane emissions are lower than carbon dioxide emissions, it is considered a major greenhouse gas because each methane molecule has 25 times the global warming potential of a carbon dioxide molecule. Nitrous oxide is released from bacteria in soil. Modern agricultural practices — tilling and soil cultivation, livestock waste management, and the use of nitrogen-rich fertilizers — contribute significantly to nitrous oxide emissions. A single nitrous oxide molecule has 298 times the global warming potential of a carbon dioxide molecule. Additional greenhouse gases include hydrofluorocarbons (1,430-14,800 time the global warming potential of carbon dioxide), sulfur hexafluoride (22,800 times the global warming potential of carbon dioxide), and water vapor. Learn more about “climate forcing” greenhouse gases. Of the twenty greenhouse gases, carbon dioxide accounts for by far the largest share of radiative forcing since 1990, and its contribution continues to grow at a steady rate. Source: US EPA. If the Greenhouse Effect is Natural, Then What’s the Problem with Greenhouse Gases? Modern climate change is caused by an excess of greenhouse gases. This, in turn, over-insulates the planet. As a result, temperatures rise. Imagine wearing a winter parka in the tropics. The effect is similar — too much insulation causes the planet to overheat, which has already begun to change the climate. Learn more about the impacts of climate change. Since the Industrial Era began, humans have had an increasing effect on climate, particularly by adding billions of tons of heat-trapping greenhouse gases to the atmosphere. Source: US EPA. Case Study CategoriesAdaptation Carbon Finance Education and Outreach Mitigation Browse By Land TypeCoastal Lands Designated Areas Forest Lands Grasslands, Shrublands, Savannas, and Deserts Water Resources Working Lands Working Lands – Agriculture Working Lands – Aquaculture Working Lands – Forests Browse By ImpactChanging Ocean Systems Acidification Rising Sea Levels Strengthening Storms Changing Water Regimes Altered Precipitation Altered Water Levels Greater Flood Risk Impacts to Species and Habitats Coral Bleaching and Reef Degradation Habitat Shifts Shifting Seasons Changing Temperatures Extreme Temperature Change: Air Temperatures Extreme Temperature Change: Water Temperatures Relevant Termsadapt adaptation adaptation planning adaptive management altered precipitation biodiversity carbon sequestration climate change climate change impacts coastal lands communications designated areas easements ecosystem services education fire flooding / inundation forests funding geo-spatial tools grasslands green infrastructure habitat inspire mitigation Natural climate solutions prepare renewable energy resilience restoration sea level rise smart growth stakeholder engagement strategic conservation targeted management uncertainty urban visualization tools vulnerability warming warming temperatures water resources wetlands working lands working waters Land Trust Alliance Press Room Learning Center Privacy Policy Sitemap Contact Us [email protected] 202.638.4725 Copyright © 2021, Land Trust Alliance. All rights reserved.
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