Greenhouse gases
Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases which allow direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in the visible and ultraviolet portion of the spectra) heats the surface, longer-wave (infrared) energy (heat) is reradiated to the atmosphere. Greenhouse gases absorb this energy, thereby allowing less heat to escape back to space, and 'trapping' it in the lower atmosphere.
Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6).
Atmospheric concentrations of both the natural and man-made gases have been rising over the last few centuries due to the industrial revolution. As the global population has increased and our reliance on fossil fuels (such as coal, oil and natural gas) has been firmly solidified, so emissions of these gases have risen. While gases such as carbon dioxide occur naturally in the atmosphere, through our interference with the carbon cycle (through burning forest lands, or mining and burning coal), we artificially move carbon from solid storage to its gaseous state, thereby increasing atmospheric concentrations.
Each gas's effect on climate change depends on three main factors:
How much of these gases are in the atmosphere?
Concentration, or abundance, is the amount of a particular gas in the air. Larger emissions of greenhouse gases lead to higher concentrations in the atmosphere. Greenhouse gas concentrations are measured in parts per million, parts per billion, and even parts per trillion. One part per million is equivalent to one drop of water diluted into about 13 gallons of liquid.
How long do they stay in the atmosphere?
Each of these gases can remain in the atmosphere for different amounts of time, ranging from a few years to thousands of years. All of these gases remain in the atmosphere long enough to become well mixed, meaning that the amount that is measured in the atmosphere is roughly the same all over the world, regardless of the source of the emissions.
How strongly do they impact global temperatures?
Some gases are more effective than others at making the planet warmer and "thickening the Earth's blanket."
For each greenhouse gases, a Global Warming Potential (GWP) has been calculated to reflect how long it remains in the atmosphere, on average, and how strongly it absorbs energy. Gases with a higher GWP absorb more energy, per pound, than gases with a lower GWP, and thus contribute more to warming Earth.
The primary sources of greenhouse gas emissions are:
Electricity production
electricity comes from burning fossil fuels, mostly coal and natural gas.
Transportation
Greenhouse gas emissions from transportation primarily come from burning fossil fuel for our cars, trucks, ships, trains, and planes.
Industry
Greenhouse gas emissions from industry primarily come from burning fossil fuels for energy as well as greenhouse gas emissions from certain chemical reactions necessary to produce goods from raw materials.
Commercial and Residential
Greenhouse gas emissions from businesses and homes arise primarily from fossil fuels burned for heat, the use of certain products that contain greenhouse gases, and the handling of waste.
Agriculture
Greenhouse gas emissions from agriculture come from livestock such as cows, agricultural soils, and rice production.
Land Use and Forestry
Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions.
Global Emissions by Source
Global greenhouse gas emissions can also be broken down by the economic activities that lead to their production.
Energy Supply (26% of 2004 global greenhouse gas emissions) - The burning of coal, natural gas, and oil for electricity and heat is the largest single source of global greenhouse gas emissions.
Industry (19% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from industry primarily involve fossil fuels burned on-site at facilities for energy. This sector also includes emissions from chemical, metallurgical, and mineral transformation processes not associated with energy consumption. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
Land Use, Land-Use Change, and Forestry (17% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from this sector primarily include carbon dioxide (CO2) emissions from deforestation, land clearing for agriculture, and fires or decay of peat soils. This estimate does not include the CO2 that ecosystems remove from the atmosphere. The amount of CO2 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 CO2 as is lost by deforestation.
Agriculture (14% of 2004 GHG emissions) - global greenhouse gas emissions) - Greenhouse gas emissions from agriculture mostly come from the management of agricultural soils, livestock, rice production, and biomass burning.
Transportation (13% of 2004 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.
Commercial and Residential Buildings (8% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from this sector arise from on-site energy generation and burning fuels for heat in buildings or cooking in homes. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
Waste and Wastewater (3% of 2004 global greenhouse gas emissions) - The largest source of greenhouse gas emissions in this sector is landfill methane (CH4), followed by wastewater methane (CH4) and nitrous oxide (N2O). Incineration of some waste products that were made with fossil fuels, such as plastics and synthetic textiles, also results in minor emissions of CO2.
Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases which allow direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in the visible and ultraviolet portion of the spectra) heats the surface, longer-wave (infrared) energy (heat) is reradiated to the atmosphere. Greenhouse gases absorb this energy, thereby allowing less heat to escape back to space, and 'trapping' it in the lower atmosphere.
Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while others are synthetic. Those that are man-made include the chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs) and Perfluorocarbons (PFCs), as well as sulfur hexafluoride (SF6).
Atmospheric concentrations of both the natural and man-made gases have been rising over the last few centuries due to the industrial revolution. As the global population has increased and our reliance on fossil fuels (such as coal, oil and natural gas) has been firmly solidified, so emissions of these gases have risen. While gases such as carbon dioxide occur naturally in the atmosphere, through our interference with the carbon cycle (through burning forest lands, or mining and burning coal), we artificially move carbon from solid storage to its gaseous state, thereby increasing atmospheric concentrations.
Each gas's effect on climate change depends on three main factors:
How much of these gases are in the atmosphere?
Concentration, or abundance, is the amount of a particular gas in the air. Larger emissions of greenhouse gases lead to higher concentrations in the atmosphere. Greenhouse gas concentrations are measured in parts per million, parts per billion, and even parts per trillion. One part per million is equivalent to one drop of water diluted into about 13 gallons of liquid.
How long do they stay in the atmosphere?
Each of these gases can remain in the atmosphere for different amounts of time, ranging from a few years to thousands of years. All of these gases remain in the atmosphere long enough to become well mixed, meaning that the amount that is measured in the atmosphere is roughly the same all over the world, regardless of the source of the emissions.
How strongly do they impact global temperatures?
Some gases are more effective than others at making the planet warmer and "thickening the Earth's blanket."
For each greenhouse gases, a Global Warming Potential (GWP) has been calculated to reflect how long it remains in the atmosphere, on average, and how strongly it absorbs energy. Gases with a higher GWP absorb more energy, per pound, than gases with a lower GWP, and thus contribute more to warming Earth.
The primary sources of greenhouse gas emissions are:
Electricity production
electricity comes from burning fossil fuels, mostly coal and natural gas.
Transportation
Greenhouse gas emissions from transportation primarily come from burning fossil fuel for our cars, trucks, ships, trains, and planes.
Industry
Greenhouse gas emissions from industry primarily come from burning fossil fuels for energy as well as greenhouse gas emissions from certain chemical reactions necessary to produce goods from raw materials.
Commercial and Residential
Greenhouse gas emissions from businesses and homes arise primarily from fossil fuels burned for heat, the use of certain products that contain greenhouse gases, and the handling of waste.
Agriculture
Greenhouse gas emissions from agriculture come from livestock such as cows, agricultural soils, and rice production.
Land Use and Forestry
Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions.
Global Emissions by Source
Global greenhouse gas emissions can also be broken down by the economic activities that lead to their production.
Energy Supply (26% of 2004 global greenhouse gas emissions) - The burning of coal, natural gas, and oil for electricity and heat is the largest single source of global greenhouse gas emissions.
Industry (19% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from industry primarily involve fossil fuels burned on-site at facilities for energy. This sector also includes emissions from chemical, metallurgical, and mineral transformation processes not associated with energy consumption. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
Land Use, Land-Use Change, and Forestry (17% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from this sector primarily include carbon dioxide (CO2) emissions from deforestation, land clearing for agriculture, and fires or decay of peat soils. This estimate does not include the CO2 that ecosystems remove from the atmosphere. The amount of CO2 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 CO2 as is lost by deforestation.
Agriculture (14% of 2004 GHG emissions) - global greenhouse gas emissions) - Greenhouse gas emissions from agriculture mostly come from the management of agricultural soils, livestock, rice production, and biomass burning.
Transportation (13% of 2004 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.
Commercial and Residential Buildings (8% of 2004 global greenhouse gas emissions) - Greenhouse gas emissions from this sector arise from on-site energy generation and burning fuels for heat in buildings or cooking in homes. (Note: Emissions from electricity use are excluded and are instead covered in the Energy Supply sector.)
Waste and Wastewater (3% of 2004 global greenhouse gas emissions) - The largest source of greenhouse gas emissions in this sector is landfill methane (CH4), followed by wastewater methane (CH4) and nitrous oxide (N2O). Incineration of some waste products that were made with fossil fuels, such as plastics and synthetic textiles, also results in minor emissions of CO2.
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