Green House Gasses
Why be concerned about green house gasses?
One of the main causes of Global Warming is excessive quantities of green house gases in Earth’s atmosphere. Read about the definition for global warming.
Of the Sun’s energy that enters the Earth’s atmosphere, greenhouse gases trap a part of the energy while the rest of the heat is radiated back to the space. This is actually a natural phenomenon – green house effect – which warms the Earth and makes it livable. If there are no green house gasses in our atmosphere, our Earth’s surface would be an average of about 60 degrees Fahrenheit cooler.
But the rapid rise in greenhouse gases is a problem because it is changing the climate faster than some living things are able to adapt. Unpredictable and new climate conditions pose unique challenges to all life.
Major greenhouse gases
Examples of green house gasses include Carbon Dioxide, water vapor, Methane, Nitrous Oxide, Ozone, CFCs, etc.
Some greenhouse gases such as Carbon Dioxide, water vapor, Methane, Nitrous Oxide, and Ozone occur naturally and are emitted to the atmosphere through natural as well as man-made processes.
Other green house gasses such as HFCs (Hydrofluorocarbons), PFCs (Perfluorocarbons), and SF6 (Sulfur hexafluoride) are created and emitted solely through human activities.
Water vapor, the gaseous form of water, is formed due to the evaporation of water and also through the sublimation of ice.
There is constant production of water vapor in the atmosphere because of evaporation from our huge water bodies like the oceans. Ultimately, this water vapor is removed from the atmosphere through condensation.
Human activities such as irrigated fields also contribute in formation of water vapor. However the amount of vapor produced in this case is comparatively negligible. Water vapor is not easy to measure and scientists are uncertain as to the exact part that it plays in global warming.
Carbon dioxide (CO2)
Other than biological processes like respiration, CO2 is created by burning fuels like oil, diesel, organic-diesel, petrol, gasoline organic-petrol, coal, natural gas and ethanol.
The emissions of CO2 have been increasing noticeably within the last 50 years and are still increasing by approximately 3% each year. Power plants emitting Carbon Dioxide are considered one of the major contributors of this green house gas to the Earth’s atmosphere.
Carbon dioxide gas is one of greatest causes of Global Warming, because it is one of the most abundant green house gasses in our Earth’s atmosphere today and because of its atmospheric longevity.
To get an idea of the effects of a runaway green house effect caused by high carbon dioxide concentrations in the atmosphere, we can take a look at Venus – its atmosphere comprises 96% carbon dioxide by volume and the planet has a surface temperature of 400 degree Celsius. Fortunately, planet Earth has the benefit of carbon sinks which absorb carbon dioxide from the atmosphere and stores it in other forms. However, the capacity of these sinks is not limitless. The earth’s carbon storage abilities can no longer match the fast rate that humans are emitting carbon dioxide into the atmosphere today, and hence, the carbon cycle has been disrupted.
Methane is more than 20 times as effective as CO2 at trapping heat. As a greenhouse gas, it plays an important role in keeping Earth warm, so that life on Earth would be possible. However, in excessive quantities, Methane becomes a major contributor of global warming.
In nature, Methane is released from the wetlands or bogs. In the wetlands or bogs where oxygen is lacking, bacteria breaks down the organic matter present anaerobically, releasing methane into the air. Natural wetlands account for about 170 Tg of Methane per year.
Methane is also released by animals. The quantity emitted is not significant in nature, but with large scale farming of animals to meet the world’s increasing demand for meat, the proportion of methane emitted by animals has increased.
Two other major sources of Methane emission are the landfill, where rubbish is dumped, and coal mining.
Nitrous Oxide (N2O)
The average concentration of Nitrous Oxide in the atmosphere is now increasing at a rate of 0.2 to 0.3% per year.
Naturally, Nitrous Oxide is produced by oceans and rainforests. In the oceans, N2O is produced by microbial processes that occur both in the water column and in sediments. Ultimately these gases can enter the atmosphere. In rainforests, natural emissions of N2O primarily result from bacterial breakdown of nitrogen in soils.
Man-made sources of Nitrous Oxide include nylon and nitric acid production, cars with catalytic converters, the use of nitrous fertilizers in agriculture and the burning of organic matter.
There are other gases, such as Chlorofluorocarbons which have been used extensively as aerosol-spray propellants, refrigerants, solvents and foam-blowing agents (which have been banned in many parts of the world because they also degrade the ozone layer), which have heat-trapping potential as high as thousands of times greater than CO2.
Other than the above green house gasses, there are many others like Nitrogen Trifluoride, Sulfur Hexafluoride, Hydrofluorocarbons and Perfluorocarbon. However, they are usually found in smaller quantities and hence are not considered to be significant green house gases.
Anthropogenic greenhouse gas emission has been attributed to eight main economic sectors. The largest contributors are power stations (many of which burn fossil fuels like coal), industrial processes (including manufacturers of cement), transportation fuels (mainly fossil fuels), and agricultural by-products (mainly methane from animals and nitrous oxide from fertilizers).
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