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Global Green House Gas Emission Facts
Aug 12, 2015

When sunlight reaches Earth’s surface, it can either be reflected back into space or absorbed by Earth. Once absorbed, the planet releases some of the energy back into the atmosphere as heat (also called infrared radiation). Greenhouse gases (GHGs) like water vapor (H2O), carbon dioxide (CO2), and methane (CH4) absorb energy, slowing or preventing the loss of heat to space. In this way, GHGs act like a blanket, making Earth warmer than it would otherwise be. This process is commonly known as the “greenhouse effect.

Greenhouse Gases

Main Green House Gases

1. Carbon Dioxide:
The natural production and absorption of carbon dioxide (CO2) is achieved through the terrestrial biosphere and the ocean. However, humankind has Carbon Dioxidealtered the natural carbon cycle by burning coal, oil, natural gas and wood and since the industrial revolution began in the mid 1700s, each of these activities has increased in scale and distribution. Carbon dioxide was the first greenhouse gas demonstrated to be increasing in atmospheric concentration with the first conclusive measurements being made in the last half of the 20th century. Prior to the industrial revolution, concentrations were fairly stable at 280ppm. Today, they are around 370ppm, an increase of well over 30 percent.  Human activities currently release over 30 billion tons of CO2 into the atmosphere every year.  

2. Methane:  Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills. It is an extremely effective absorber of radiation, though its atmospheric concentration is less than CO2 and its lifetime in the atmosphere is brief (10-12 years), compared to some other greenhouse gases (such as CO2, N2O, CFCs). 

Over the last 50 years, human activities such as growing rice, raising cattle, using natural gas and mining coal have added to the atmospheric concentration of methane. 

3. Nitrous Oxide:
Nitrous oxide is produced through natural and human activities, mainly through agricultural activities and natural biological processes. Fuel burning and some other processes also create N2O. Concentrations of N2O have risen approximately 18% since the start of the Industrial Revolution, with a relatively rapid increase towards the end of the 20th century.

Global Green house

Fig:  Global Green house Gas emission by Gas

4. F-Gases: They have no natural sources and Industrial processes, refrigeration, and the use of a variety of consumer products contribute to emissions of F-gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

F Gases

5. Water Vapor: Water Vapor is the most abundant greenhouse gas in the atmosphere and also the most important in terms of its contribution to the natural greenhouse effect, despite having a short atmospheric lifetime. Some human activities can influence local water vapor levels. However, on a global scale, the concentration of water vapor is controlled by temperature, which influences overall rates of evaporation and precipitation. Therefore, the global concentration of water vapor is not substantially affected by direct human emissions.

6. Tropospheric ozone (O3): It has a short atmospheric lifetime, is a potent greenhouse gas. Chemical reactions create ozone from emissions of nitrogen oxides and volatile organic compounds from automobiles, power plants, and other industrial and commercial sources in the presence of sunlight. In addition to trapping heat, ozone is a pollutant that can cause respiratory health problems and damage crops and ecosystems.

Green House Gas emission by Source

⇒ Energy Supply - The burning of coal, natural gas, and oil for electricity and heat is the Green House Gas emission by Sourcelargest single source of global greenhouse gas emissions.

⇒ Industry - 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. 

⇒ Land Use, Land-Use Change, and Forestry 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 Greenhouse gas emissions from agriculture mostly come from the management of agricultural soils, livestock, rice production, and biomass burning.

⇒ Transportation - 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 - Greenhouse gas emissions from this sector arise from on-site energy generation and burning fuels for heat in buildings or cooking in homes.

⇒ Waste and Wastewater - 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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