Overview Of Greenhouse Gases

Gases that entice heat in the environment are known as greenhouse gases. This part supplies information on emissions and removals of the main greenhouse gases to and from the environment. For extra data on the opposite local weather forcers, corresponding to black carbon, please visit the Climate Change Indicators: Climate Forcing page.

Carbon dioxide (CO2): Carbon dioxide enters the environment by way of burning fossil fuels (coal, natural gas, and oil), solid waste, timber and other biological materials, and in addition because of sure chemical reactions (e.g., cement manufacturing). Carbon dioxide is removed from the ambiance (or "sequestered") when it is absorbed by plants as part of the biological carbon cycle.Methane (CH4): Methane is emitted during the production and transport of coal, pure fuel, and oil. Methane emissions additionally end result from livestock and different agricultural practices, land use, and by the decay of organic waste in municipal stable waste landfills.Nitrous oxide (N2O): Nitrous oxide is emitted throughout agricultural, land use, and industrial actions; combustion of fossil fuels and stable waste; as well as during remedy of wastewater.Fluorinated gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are artificial, powerful greenhouse gases which are emitted from a variety of family, commercial, and industrial functions and processes. Fluorinated gases (particularly hydrofluorocarbons) are typically used as substitutes for stratospheric ozone-depleting substances (e.g., chlorofluorocarbons, hydrochlorofluorocarbons, and halons). Fluorinated gases are usually emitted in smaller portions than other greenhouse gases, but they are potent greenhouse gases. With global warming potentials (GWPs) that usually vary from thousands to tens of hundreds, they are typically known as high-GWP gases as a result of, for a given quantity of mass, they lure considerably more heat than CO2.

Each fuel's effect on local weather change will depend on three predominant factors:

How ample are greenhouse gases within the atmosphere?

Concentration, or abundance, is the quantity of a specific gas within the air. Larger emissions of greenhouse gases lead to higher concentrations in the ambiance. Greenhouse gas concentrations are measured in elements per million, parts per billion, and even components per trillion. One half per million is equivalent to one drop of water diluted into about 13 gallons of liquid (roughly the gasoline tank of a compact car). To study more concerning the rising concentrations of greenhouse gases in the ambiance, go to the Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases page.

How long do greenhouse gases stay in the ambiance?

Each of those gases can stay in the atmosphere for various quantities of time, ranging from a couple of years to thousands of years. All of those gases remain in the ambiance long enough to turn into well mixed, which means that the quantity that is measured within the atmosphere is roughly the identical all over the world, regardless of the source of the emissions.

How strongly do greenhouse gases impact the ambiance?

Some gases are simpler than others at making the planet hotter and "thickening the Earth's atmospheric blanket."

For each greenhouse gasoline, a world Warming Potential (GWP) was developed to allow comparisons of the worldwide warming impacts of various gases. Specifically, it is a measure of how a lot power the emissions of 1 ton of a fuel will absorb over a given period of time, sometimes a 100-12 months time horizon, relative to the emissions of 1 ton of carbon dioxide (CO2). Gases with a higher GWP absorb more energy, per ton emitted, than gases with a decrease GWP, and thus contribute more to warming Earth.

Note: All emission estimates are from the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2021. The Inventory makes use of 100-year GWPs from IPCC’s Fifth Assessment Report (AR5).

Carbon Dioxide Emissions

Chemical Formula: CO2Lifetime in Atmosphere: See below1Global Warming Potential (100-year): 1

Carbon dioxide (CO2) is the primary greenhouse fuel emitted through human activities. In 2021, CO2 accounted for 79% of all U.S. greenhouse gasoline emissions from human actions. Carbon dioxide is naturally current in the ambiance as a part of the Earth's carbon cycle (the pure circulation of carbon among the many environment, oceans, soil, plants, and animals). Human actions are altering the carbon cycle-both by adding more CO2 to the ambiance and by influencing the ability of natural sinks, like forests and soils, to take away and store CO2 from the environment. While CO2 emissions come from a wide range of natural sources, human-associated emissions are accountable for the rise that has occurred within the atmosphere since the industrial revolution.2

The main human activity that emits CO2 is the combustion of fossil fuels (coal, natural gas, and oil) for power and transportation. Certain industrial processes and land-use adjustments also emit CO2. The primary sources of CO2 emissions within the United States are described beneath.

Transportation. The combustion of fossil fuels resembling gasoline and diesel to transport folks and goods was the largest supply of CO2 emissions in 2021, accounting for 35% of complete U.S. CO2 emissions and 28% of complete U.S. greenhouse fuel emissions. This class includes domestic transportation sources reminiscent of freeway and passenger automobiles, air travel, marine transportation, and rail.Electricity. Electricity is a key supply of energy in the United States and is used to energy homes, business, and industry. In 2021, the combustion of fossil fuels to generate electricity was the second largest source of CO2 emissions in the nation, accounting for 31% of whole U.S. CO2 emissions and 24% of complete U.S. greenhouse gas emissions. The forms of fossil fuel used to generate electricity emit completely different quantities of CO2. To produce a given amount of electricity, burning coal will produce extra CO2 than pure gasoline or oil.Industry. Many industrial processes emit CO2 by means of fossil gas consumption. Several processes also produce CO2 emissions by means of chemical reactions that don't contain combustion, and examples embrace the production of mineral products similar to cement, the manufacturing of metals resembling iron and steel, and the production of chemicals. The fossil fuel combustion element of assorted industrial processes accounted for 15% of complete U.S. CO2 emissions and 12% of complete U.S. greenhouse gasoline emissions in 2021. Many industrial processes additionally use electricity and therefore indirectly end in CO2 emissions from electricity era.

Carbon dioxide is consistently being exchanged among the many atmosphere, ocean, and land surface as it is both produced and absorbed by many microorganisms, plants, and animals. Emissions and removals of CO2 by these pure processes, however, are inclined to stability over time, absent anthropogenic impacts. Because the Industrial Revolution began around 1750, human actions have contributed considerably to climate change by adding CO2 and different heat-trapping gases to the atmosphere.

Within the United States, the administration of forests and different land (e.g., cropland, grasslands, and so forth.) has acted as a internet sink of CO2, which implies that extra CO2 is removed from the ambiance, and stored in plants and timber, than is emitted. This carbon sink offset about 13% of whole emissions in 2021. For more particulars, see the discussion within the Land Use, Land-Use Change, and Forestry part.

To find out more about the function of CO2 in warming the ambiance and its sources, go to the Climate Change Indicators web page.

Carbon dioxide emissions in the United States decreased by 2% between 1990 and 2021. For the reason that combustion of fossil gas is the most important supply of greenhouse gasoline emissions in the United States, modifications in emissions from fossil gas combustion have historically been the dominant factor affecting complete U.S. emission tendencies. Changes in CO2 emissions from fossil fuel combustion are influenced by many lengthy-term and short-term components, together with population growth, financial growth, changing power prices, new technologies, altering behavior, and seasonal temperatures. In 2021, the increase in CO2 emissions from fossil gasoline combustion corresponded with an increase in power use as a result of economic activity rebounding after the height of the COVID-19 pandemic, along with an increase in coal use within the electric energy sector.

Reducing Carbon Dioxide Emissions

The most effective manner to reduce CO2 emissions is to reduce fossil fuel consumption. Many strategies for decreasing CO2 emissions from energy are cross-slicing and apply to houses, businesses, trade, and transportation.

Improving the insulation of buildings, traveling in more gasoline-efficient autos, and using extra efficient electrical appliances are all ways to reduce vitality use, and thus CO2 emissions.

- See EPA's Energy STAR® program for more info on energy-efficient appliances and methods to save lots of at residence and work.- See EPA's and DOE's fueleconomy.gov site for more information on fuel-efficient automobiles.- Learn about EPA's motorcar standards that improve car efficiency and save drivers cash.

Reducing private power use by turning off lights and electronics when not in use reduces electricity demand. Reducing distance traveled in autos reduces petroleum consumption. Both are ways to scale back power CO2 emissions by way of conservation.

Learn more about What You can do at Home, in school, within the Office, and on the Road to avoid wasting energy and scale back your carbon footprint.

Producing extra vitality from renewable sources and utilizing fuels with decrease carbon contents are methods to reduce carbon emissions.

Carbon dioxide capture and sequestration is a set of technologies that may potentially drastically reduce CO2 emissions from new and present coal- and gas-fired energy plants, industrial processes, and other stationary sources of CO2. For example, a CCS challenge would possibly capture CO2 from the stacks of a coal-fired energy plant earlier than it enters the atmosphere, transport the CO2 by way of pipeline, and inject the CO2 deep underground at a carefully chosen and appropriate subsurface geologic formation, such as a close by abandoned oil discipline, where it's securely stored.

Learn more about CCS.

Learn more about Land Use, Land Use Change and Forestry Sector.

1 Atmospheric CO2 is part of the global carbon cycle, and therefore its destiny is a posh perform of geochemical and biological processes. A few of the excess carbon dioxide will be absorbed rapidly (for example, by the ocean floor), but some will remain in the atmosphere for 1000's of years, due in part to the very sluggish process by which carbon is transferred to ocean sediments.

2IPCC (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2391 pp.

Methane Emissions

Chemical Formula: CH4Lifetime in Atmosphere: 12 yearsGlobal Warming Potential (100-yr): 281

In 2021, methane (CH4) accounted for 12% of all U.S. greenhouse fuel emissions from human actions. Human activities emitting methane embody leaks from natural gasoline programs and the elevating of livestock. Methane can also be emitted by pure sources comparable to termites. As well as, natural processes in soil and chemical reactions within the environment help take away CH4 from the ambiance. Methane's lifetime in the environment is way shorter than carbon dioxide (CO2), however CH4 is extra environment friendly at trapping radiation than CO2. Pound for pound, the comparative influence of CH4 is 28 times larger than CO2 over a 100-12 months interval.1

Globally, 50-65% of complete CH4 emissions come from human actions.2 Methane is emitted from vitality, trade, agriculture, land use, and waste administration activities, described beneath.

Agriculture. Domestic livestock reminiscent of cattle, swine, sheep, and goats produce CH4 as part of their normal digestive course of. Also, when animal manure is saved or managed in lagoons or holding tanks, CH4 is produced. Because people elevate these animals for meals and other merchandise, the emissions are thought-about human-related. The Agriculture sector is the most important source of CH4 emissions within the United States. For extra information, see the Inventory of U.S. Greenhouse Gas Emissions and Sinks Agriculture chapter.LULUCF: While not shown within the figure, emissions of CH4 also happen because of land use and land administration activities in the Land Use, Land-Use Change, and Forestry sector (e.g. forest and grassland fires, administration of flooded lands resembling reservoirs, decomposition of organic matter in coastal wetlands).Energy and Industry. Natural fuel and petroleum programs are the second largest supply of CH4 emissions in the United States. Methane is emitted to the atmosphere through the production, processing, storage, transmission, distribution, and use of pure gasoline, and the manufacturing, refinement, transportation, and storage of crude oil. Coal mining is also a source of CH4 emissions. For extra information, see the Inventory of U.S. Greenhouse Gas Emissions and Sinks sections on Natural Gas Systems and Petroleum Systems.Waste from Homes and Businesses. Methane is generated in landfills as waste decomposes and in the treatment of wastewater. Landfills are the third-largest source of CH4 emissions in the United States. Methane is also generated from home and industrial wastewater remedy and from composting and anaerobic digestion. For extra info, see the Inventory of U.S. Greenhouse Gas Emissions and Sinks Waste chapter.

Methane can be emitted from a number of natural sources. Natural wetlands that are not managed or modified by human exercise are the most important source, emitting CH4 from bacteria that decompose organic supplies in the absence of oxygen. Reservoirs and ponds with high natural matter and low oxygen levels additionally produce methane through the microbial breakdown of natural matter. Smaller sources embody termites, oceans, sediments, volcanoes, and wildfires.

To find out extra about the position of CH4 in warming the ambiance and its sources, go to the Climate Change Indicators page.

Methane emissions in the United States decreased by 16% between 1990 and 2021. During this time period, emissions elevated from sources associated with agricultural actions, whereas emissions decreased from other sources including landfills and coal mining and from pure gas and petroleum methods.

Reducing Methane Emissions

There are a number of how to cut back CH4 emissions. Some examples are mentioned under. EPA has a series of voluntary applications for decreasing CH4 emissions, along with regulatory initiatives. EPA additionally helps the worldwide Methane Initiative, a global partnership encouraging world methane discount strategies.

Upgrading the gear used to produce, store, and transport oil and natural gas can scale back most of the leaks that contribute to CH4 emissions. Methane from coal mines can also be captured and used for energy. Learn more in regards to the EPA's Natural Gas STAR Program and Coalbed Methane Outreach Program.

Methane from manure administration practices might be decreased and captured by altering manure management methods. Additionally, modifications to animal feeding practices could reduce emissions from enteric fermentation. Learn more about improved manure administration practices at EPA's AgSTAR Program.

Capturing landfill CH4 for destruction in a flare or conversion to renewable energy are each efficient emission discount strategies. Learn extra about these alternatives and the EPA's Landfill Methane Outreach Program. Additionally, managing waste at a higher tier on the waste management hierarchy can cut back CH4 technology at landfills. Learn extra about Sustainable Materials Management.

1IPCC (2013). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Stocker, T.F., D. Qin, G.K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.2 IPCC (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2391 pp.

Nitrous Oxide Emissions

Chemical Formula: N2OLifetime in Atmosphere: 114 yearsGlobal Warming Potential (100-yr): 2651

In 2021, nitrous oxide (N2O) accounted for 6% of all U.S. greenhouse gas emissions from human activities. Human actions reminiscent of agriculture, gas combustion, wastewater management, and industrial processes are rising the quantity of N2O within the atmosphere. Nitrous oxide is also naturally present in the ambiance as part of the Earth's nitrogen cycle and has a wide range of natural sources. Nitrous oxide molecules stay within the atmosphere for a mean of 121 years earlier than being eliminated by a sink or destroyed by chemical reactions. The impact of 1 pound of N2O on warming the environment is 265 times that of 1 pound of carbon dioxide.1

Globally, 40% of whole N2O emissions come from human activities.2 Nitrous oxide is emitted from agriculture, land use, transportation, business, and other actions, described beneath.

Agriculture. Nitrous oxide can outcome from various agricultural soil administration activities, akin to application of artificial and natural fertilizers and different cropping practices, the management of manure, or burning of agricultural residues. Agricultural soil management is the largest supply of N2O emissions in the United States, accounting for 75% of total U.S. N2O emissions in 2021. While not shown in the determine and less important, emissions of N2O additionally happen as a result of land use and land administration activities in the Land Use, Land-Use Change, and Forestry sector (e.g. forest and grassland fires, utility of synthetic nitrogen fertilizers to city soils (e.g., lawns, golf programs) and forest lands, etc.).Fuel Combustion. Nitrous oxide is emitted when fuels are burned. The quantity of N2O emitted from burning fuels depends upon the type of fuel and combustion technology, upkeep, and operating practices.Industry. Nitrous oxide is generated as a byproduct throughout the manufacturing of chemicals corresponding to nitric acid, which is used to make synthetic commercial fertilizer, and within the manufacturing of adipic acid, which is used to make fibers, like nylon, and other artificial products. Nitrous oxide can also be emitted from use in other functions similar to anesthesia and semiconductor manufacturing.Waste. Nitrous oxide can also be generated from remedy of domestic wastewater during nitrification and denitrification of the nitrogen current, normally within the type of urea, ammonia, and proteins.

Nitrous oxide emissions occur naturally via many sources associated with the nitrogen cycle, which is the pure circulation of nitrogen among the environment, plants, animals, and microorganisms that dwell in soil and water. Nitrogen takes on quite a lot of chemical types all through the nitrogen cycle, including N2O. Natural emissions of N2O are mainly from micro organism breaking down nitrogen in soils and the oceans. Nitrous oxide is faraway from the environment when it is absorbed by certain varieties of micro organism or destroyed by ultraviolet radiation or chemical reactions.

To search out out more about the sources of N2O and its function in warming the ambiance, go to the Climate Change Indicators web page.

Nitrous oxide emissions within the United States decreased by 3% between 1990 and 2021. During this time, nitrous oxide emissions from mobile combustion decreased by 56% as a result of standards pollutant emission standards for on-road vehicles. Nitrous oxide emissions from agricultural soils have various during this interval and have been about the same in 2021 as in 1990.

Reducing Nitrous Oxide Emissions

There are a selection of the way to reduce emissions of N2O, discussed under.

The applying of nitrogen fertilizers accounts for the vast majority of N2O emissions within the United States. Emissions could be decreased by reducing nitrogen-primarily based fertilizer functions and applying these fertilizers more efficiently,3 in addition to modifying a farm's manure management practices.

- Nitrous oxide is a byproduct of gasoline combustion, so reducing gasoline consumption in motor vehicles and secondary sources can reduce emissions.- Additionally, the introduction of pollution control technologies (e.g., catalytic converters to scale back exhaust pollutants from passenger vehicles) may also cut back emissions of N2O.

- Nitrous oxide is generally emitted from industry by fossil gasoline combustion, so technological upgrades and gasoline switching are effective ways to cut back industry emissions of N2O.- Production of nitric acid and adipic acid end in N2O emissions that may be lowered by way of technological upgrades and use of abatement gear.

1IPCC (2013). Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Stocker, T.F., D. Qin, G.K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.2IPCC (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2391 pp.3EPA (2005). Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture. U.S. Environmental Protection Agency, Washington, DC, USA.

Emissions of Fluorinated Gases

Chemical Formulas: HFCs, PFCs, NF3, SF6Lifetime in Atmosphere: HFCs: as much as 270 years PFCs: 2,600-50,000 years NF3: 740 years SF6: 3,200 yearsGlobal Warming Potential (100-12 months):1 HFCs: up to 12,four hundred PFCs: up to 11,one hundred NF3: 16,100 SF6: 23,500

Unlike many other greenhouse gases, fluorinated gases have no important natural sources and are available virtually solely from human-related actions. They are emitted through their use as substitutes for ozone-depleting substances (e.g., as refrigerants) and through quite a lot of industrial processes akin to aluminum and semiconductor manufacturing. Many fluorinated gases have very excessive international warming potentials (GWPs) relative to different greenhouse gases, so small atmospheric concentrations can however have massive results on world temperatures. They'll even have lengthy atmospheric lifetimes-in some cases, lasting hundreds of years. Like other lengthy-lived greenhouse gases, most fluorinated gases are nicely-combined within the environment, spreading all over the world after they're emitted. Many fluorinated gases are removed from the ambiance solely when they are destroyed by sunlight within the higher atmosphere. Generally, fluorinated gases are essentially the most potent and longest lasting sort of greenhouse gases emitted by human actions.

There are four foremost classes of fluorinated gases-hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3). The biggest sources of fluorinated gas emissions are described under.

Substitution for Ozone-Depleting Substances. Hydrofluorocarbons are used as refrigerants, aerosol propellants, foam blowing agents, solvents, and fire retardants. The major emissions source of those compounds is their use as refrigerants-for instance, in air conditioning techniques in each automobiles and buildings. These chemicals had been developed as a replacement for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) as a result of they do not deplete the stratospheric ozone layer. CFCs and HCFCs are additionally greenhouse gases; nevertheless, their contribution will not be included right here because they're being phased out under a global agreement referred to as the Montreal Protocol. HFCs are potent greenhouse gases with high GWPs, and they're released into the ambiance during manufacturing processes and by way of leaks, servicing, and disposal of gear through which they are used. Newly developed hydrofluoroolefins (HFOs) are a subset of HFCs and are characterized by brief atmospheric lifetimes and decrease GWPs. HFOs are at present being introduced as refrigerants, aerosol propellants and foam blowing brokers. The American Innovation and Manufacturing (Aim) Act of 2020 directs EPA to address HFCs by providing new authorities in three important areas: to section down the production and consumption of listed HFCs within the United States by 85% over the following 15 years, handle these HFCs and their substitutes, and facilitate the transition to next-technology technologies that do not rely on HFCs.Industry. Perfluorocarbons are produced as a byproduct of aluminum production and are used within the manufacturing of semiconductors. PFCs usually have long atmospheric lifetimes and GWPs near 10,000. Sulfur hexafluoride is used in magnesium processing and semiconductor manufacturing, as well as a tracer fuel for leak detection. Nitrogen trifluoride is utilized in semiconductor manufacturing. HFC-23 is produced as a byproduct of HCFC-22 production and is used in semiconductor manufacturing.Transmission and Distribution of Electricity. Sulfur hexafluoride is used as an insulating gasoline in electrical transmission equipment, moreorless game including circuit breakers. The GWP of SF6 is 23,500 making it probably the most potent greenhouse gas that the Intergovernmental Panel on Climate Change has evaluated.

To find out extra concerning the function of fluorinated gases in warming the environment and their sources, go to the Fluorinated Greenhouse Gas Emissions page.

Trends

Overall, fluorinated gas emissions within the United States have elevated by 105% between 1990 and 2021. This increase has been driven by a 349% increase in emissions of hydrofluorocarbons (HFCs) since 1990, as they have been broadly used in its place for ozone-depleting substances. Emissions of perfluorocarbons (PFCs) and sulfur hexafluoride (SF6) have declined throughout this time because of emission-reduction efforts in the aluminum manufacturing industry (PFCs) and the electrical transmission and distribution industry (SF6).

Reducing Fluorinated Gas Emissions

Because most fluorinated gases have a really lengthy atmospheric lifetime, it should take many years to see a noticeable decline in current concentrations. There are, nevertheless, a quantity of the way to reduce emissions of fluorinated gases, described below.

Refrigerants utilized by companies and residences emit fluorinated gases. Emissions might be diminished by higher dealing with of these gases and use of substitutes with lower global warming potentials and other technological improvements. Visit EPA's Ozone Layer Protection site and HFC Phasedown site to learn more about reduction opportunities on this sector.

Industrial emitters of fluorinated gases can reduce emissions by adopting fluorinated gasoline capture and destruction processes, optimizing manufacturing to attenuate emissions, and replacing these gases with alternatives. EPA has experience with these gases in the next sectors:

AluminumMagnesiumSemiconductor

Sulfur hexafluoride is an extremely potent greenhouse gas that is used for several purposes when transmitting electricity via the ability grid. EPA is working with business to scale back emissions via the SF6 Emission Reduction Partnership for Electric Power Systems, which promotes leak detection and repair, use of recycling gear, and consideration of other applied sciences that don't use SF6.

Hydrofluorocarbons (HFCs) are released by way of the leakage of refrigerants utilized in car air-conditioning systems. Leakage will be diminished via better system components and by the use of other refrigerants with lower international warming potentials than those presently used. EPA’s light-duty and heavy-obligation car requirements offered incentives for manufacturers to supply vehicles with lower HFC emissions.

1IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Stocker, T.F., D. Qin, G.K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

6,340 million metric tons of CO2: What does that mean?

An explanation of models:

1,000,000 metric tons equals about 2.2 billion pounds, or 1 trillion grams. For comparability, a small automobile is more likely to weigh slightly more than 1 metric ton. Thus, a million metric tons is roughly the identical mass as 1 million small vehicles!

The U.S. Inventory makes use of metric units for consistency and comparability with different nations. For reference, a metric ton is slightly more (roughly 10%) than a U.S. "quick" ton.

GHG emissions are often measured in carbon dioxide (CO2) equal. To transform emissions of a gasoline into CO2 equivalent, its emissions are multiplied by the gasoline's Global Warming Potential (GWP). The GWP takes into account the truth that many gases are more effective at warming Earth than CO2, per unit mass.

The GWP values showing within the Overview of Greenhouse Gases and Sources of Greenhouse Gas internet pages mirror the values used in the U.S. Inventory, which are drawn from the IPCC’s Fifth Assessment Report (AR5). For further discussion of GWPs and an estimate of GHG emissions utilizing updated GWPs, see Annex 6 of the U.S. Inventory and the IPCC's discussion on GWPs (PDF) (151 pp, 14.2MB).