by Robert Moss

Created on: January 28, 2009

Green House Gas Emissions and Global Warming:

The global effect from Human activities, including the burning of fossil fuels, increased farming, and deforestation, is leading to an increase in the three main greenhouse gases that are present within the Earths atmosphere. These are Carbon Dioxide (CO2), Methane (CH4), and Nitrous Oxide (N2O). Greenhouse gases posses the insulating property of being able to reflect long wave radiation. Thus they act to hold heat within the atmosphere by reflecting back long wave heat radiation, which itself radiates from the Earth after it is warmed by solar radiation. Inevitably as the insulation of this long wave heat radiation increases, then so to does the temperature of the Earth's atmosphere and Oceans.

The main greenhouse gas by volume is CO2, and this has been increasing as a constituent within the Earth's atmosphere from about 270 parts per million around the year 1800 to about 400 parts per million today. A main cause of CO2 emission is from the burning of fossil fuel, which served to sequester CO2 from the atmosphere in past times. The volume of CO2 removed from the Earth's atmosphere, by the formation of fossil fuels and carbonate rocks, is indicated by past atmospheric CO2 levels. Before land based plants removed large quantities of CO2 from the atmosphere, during the Carboniferous period, the previous geological period; the Devonian, possessed atmospheric CO2 levels of approximately 2200 parts per million. This is 8 times the preindustrial atmospheric CO2 level. Although there were higher levels off atmospheric carbon dioxide in ancient geological times, the current rate of return of the sequestered CO2 is happening too quickly to allow life and climate systems to adjust.

Not all CO2 emissions stay in the atmosphere. The ocean, and to some extent the land, act as large carbon sinks which significantly slow the accumulation of atmospheric CO2, and the resulting climate change. Indeed the Oceans contain about 50 times the amount of CO2 to that held within the atmosphere. However global warming will inevitably cause seawater temperatures to rise. Warmer water holds less dissolved gas than colder water, so the ocean will not be able to store as much CO2. Consequently the effect will be to cause even higher atmospheric CO2 concentrations and a further acceleration of global warming. This combined with an increase in the release of CO2 from the soil, as temperatures rise, could lead to a runaway greenhouse effect. (Oceanus

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