Main Anthropogenic Sources of Greenhouse Gases Agriculture, Fire, Change in Land Use and Transport

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1 Main Anthropogenic Sources of Greenhouse Gases Agriculture, Fire, Change in Land Use and Transport

2 Content GHG Emissions from AFOLU GHG Emissions from Transport Land Use & Forestry as a Source of GHG Transport as a Source of GHG

3 AFOLU Agriculture Forestry and Other Land Use IPCC, WG3, AR5, Summary for Policymakers, Fig. SPM.2

4 GHG Emissions from AFOLU Agriculture, Forestry, Other Land Use AFOLU (24% of 2010 global greenhouse gas emissions) Greenhouse gas emissions from this sector primarily include carbon dioxide (CO 2 ) emissions from deforestation, land clearing for agriculture, and fires or decay of peat soils. This estimate does not include the CO 2 that ecosystems remove from the atmosphere. The amount of CO 2 that is removed is subject to large uncertainty, although recent estimates indicate that on a global scale, ecosystems on land remove about twice as much CO 2 as is lost by deforestation. Greenhouse gas emissions from agriculture mostly come from the management of agricultural soils, livestock, rice production, and biomass burning.

5 GHG Emissions from Transport Transportation (14% of 2010 global greenhouse gas emissions) Greenhouse gas emissions from this sector primarily involve fossil fuels burned for road, rail, air, and marine transportation. Almost all (95%) of the world's transportation energy comes from petroleum based fuels, largely gasoline and diesel.

6 Agriculture as a Source of GHG Agricultural activities the cultivation of crops and livestock for food contribute to emissions in a variety of ways: Various management practices for agricultural soils can lead to production and emission of nitrous oxide (N 2 O). The large number of different activities that can contribute to N 2 O emissions from agricultural lands range from fertilizer application to methods of irrigation and tillage. Management of agricultural soils accounts for over half of the emissions from the Agriculture sector. Livestock, especially cattle, produce methane (CH 4 ) as part of their digestion. This process is called enteric fermentation, and it represents almost one third of the emissions from the Agriculture sector.

7 Agriculture as a Source of GHG The way in which manure from livestock is managed also contributes to CH 4 and N 2 O emissions. Manure storage methods and the amount of exposure to oxygen and moisture can affect how these greenhouse gases are produced. Smaller sources of emissions include rice cultivation, which produces CH 4, and burning crop residues, which produce CH 4 and N 2 O.

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12 Land Use & Forestry as a Source of GHG Plants absorb carbon dioxide (CO 2 ) from the atmosphere as they grow, and they store some of the carbon throughout their lifetime. Soils can also store CO 2, depending on how the soil is managed. This storage of carbon in plants and soils is called biological carbon sequestration. Because biological sequestration takes CO 2 out of the atmosphere, it is also called a greenhouse gas sink.

13 Land Use & Forestry as a Source of GHG Emissions or sequestration of CO 2 can occur as land uses change. For example, CO 2 is exchanged between the atmosphere and the plants and soils on land as former cropland is converted into grassland, as new areas are cultivated and become cropland, or as forests grow. In addition, using biological feedstock (such as energy crops or wood) for purposes such as electricity generation, input to processes that create liquid fuels, or building materials can lead to emissions or sequestration.

14 Land Use & Forestry as a Source of GHG In the United States overall, since 1990 land use, land use change, and forestry activities have resulted in more removal of CO 2 from the atmosphere than emissions. Because of this, the Land Use, Land Use Change, and Forestry (LULUCF) sector in the United States is considered a net sink, rather than a source, of CO 2 over this period. In many areas of the world, the opposite is true: In countries where large areas of forest land are cleared, often for agricultural purposes or for settlements, the LULUCF sector can be a net source of greenhouse gas emissions.

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17 Transport as a Source of GHG The Transportation sector includes the movement of people and goods by cars, trucks, trains, ships, airplanes, and other vehicles. The majority of greenhouse gas emissions from transportation are CO2 emissions resulting from the combustion of petroleumbased products, like gasoline, in internal combustion engines. The largest sources of transportation related greenhouse gas emissions include passenger cars and light duty trucks, including sport utility vehicles, pickup trucks, and minivans. These sources account for over half of the emissions from the sector. The remainder of greenhouse gas emissions comes from other modes of transportation, including freight trucks, commercial aircraft, ships, boats, and trains as well as pipelines and lubricants.

18 Transport as a Source of GHG Relatively small amounts of methane (CH4) and nitrous oxide (N2O) are emitted during fuel combustion. In addition, a small amount of hydrofluorocarbon (HFC) emissions are included in the Transportation sector. These emissions result from the use of mobile air conditioners and refrigerated transport.

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23 Main Anthropogenic Sources of Greenhouse Gases Agriculture, Fire, Change in Land Use and Transport