CO 2 is used as the reference gas and has a GWP of one. Iron and steel production, cement production and petrochemical production are other significant sources of CO 2 emissions. Domestic livestock, landfills, and natural gas systems are the primary anthropogenic sources of CH 4.
Other significant sources include mobile and stationary combustion and livestock. Emissions averaged an increase of 0. Source: Dr. Ralph Keeling, Scripps Institution of Oceanography scrippsco2. A commonly used estimate for CO 2 lifetime is years, but this really only reflects the lifetime of a portion of the atmospheric carbon dioxide reservoir.
Tags Science Extreme Weather. Climate Basics » Climate Science. Main Greenhouse Gases. Energy production of all types accounts for 72 percent of all emissions. CO2 accounts for about 76 percent of total greenhouse gas emissions.
Methane, primarily from agriculture, contributes 16 percent of greenhouse gas emissions and nitrous oxide, mostly from industry and agriculture, contributes 6 percent to global emissions. All figures here are expressed in CO2-equivalents. Inventory of U. Our World in Data Tags Emissions.
Topics Climate Basics. Nitrous oxide is also naturally present in the atmosphere as part of the Earth's nitrogen cycle, and has a variety of natural sources. Nitrous oxide molecules stay in the atmosphere for an average of years before being removed by a sink or destroyed through chemical reactions. The impact of 1 pound of N 2 O on warming the atmosphere is almost times that of 1 pound of carbon dioxide.
Nitrous oxide emissions occur naturally through many sources associated with the nitrogen cycle, which is the natural circulation of nitrogen among the atmosphere, plants, animals, and microorganisms that live in soil and water. Nitrogen takes on a variety of chemical forms throughout the nitrogen cycle, including N 2 O. Natural emissions of N 2 O are mainly from bacteria breaking down nitrogen in soils and the oceans. Nitrous oxide is removed from the atmosphere when it is absorbed by certain types of bacteria or destroyed by ultraviolet radiation or chemical reactions.
To find out more about the sources of N 2 O and its role in warming the atmosphere, visit the Climate Change Indicators page. Nitrous oxide emissions in the United States have remained relatively flat between and Nitrous oxide emissions from mobile combustion decreased by 60 percent from to as a result of emission control standards for on-road vehicles.
Nitrous oxide emissions from agricultural soils have varied during this period and were about 9 percent higher in than in , primarily driven by increasing use of nitrogen fertilizers.
The application of nitrogen fertilizers accounts for the majority of N 2 O emissions in the United States. Emissions can be reduced by reducing nitrogen-based fertilizer applications and applying these fertilizers more efficiently, 3 as well as modifying a farm's manure management practices. Additionally, the introduction of pollution control technologies e.
Production of adipic acid results in N 2 O emissions that can be reduced through technological upgrades. Greenhouse Gas Mitigation Potential in U.
Forestry and Agriculture. Unlike many other greenhouse gases, fluorinated gases have no natural sources and only come from human-related activities.
They are emitted through their use as substitutes for ozone-depleting substances e. Many fluorinated gases have very high global warming potentials GWPs relative to other greenhouse gases, so small atmospheric concentrations can have disproportionately large effects on global temperatures. They can also have long atmospheric lifetimes—in some cases, lasting thousands of years. Like other long-lived greenhouse gases, most fluorinated gases are well-mixed in the atmosphere, spreading around the world after they are emitted.
Many fluorinated gases are removed from the atmosphere only when they are destroyed by sunlight in the far upper atmosphere. In general, fluorinated gases are the most potent and longest lasting type of greenhouse gases emitted by human activities. The largest sources of fluorinated gas emissions are described below. To find out more about the role of fluorinated gases in warming the atmosphere and their sources, visit the Fluorinated Greenhouse Gas Emissions page.
Overall, fluorinated gas emissions in the United States have increased by about 86 percent between and This increase has been driven by a percent increase in emissions of hydrofluorocarbons HFCs since , as they have been widely used as a substitute for ozone-depleting substances.
Emissions of perfluorocarbons PFCs and sulfur hexafluoride SF 6 have actually declined during this time due to emission reduction efforts in the aluminum production industry PFCs and the electricity transmission and distribution industry SF 6. Because most fluorinated gases have a very long atmospheric lifetime, it will take many years to see a noticeable decline in current concentrations.
However, there are a number of ways to reduce emissions of fluorinated gases, described below. Refrigerants used by businesses and residences emit fluorinated gases. Emissions can be reduced by better handling of these gases and use of substitutes with lower global warming potentials and other technological improvements. Industrial users of fluorinated gases can reduce emissions by adopting fluorinated gas recycling and destruction processes, optimizing production to minimize emissions, and replacing these gases with alternatives.
EPA has experience with these gases in the following sectors:.
0コメント