GREEN HOUSE GAS CONCENTRACTIONS
The global atmospheric concentration of 314 ppbv - is now about 16% greater than pre-industrial concentrations. Nitrous oxide has been responsible for about 4 to 6% of the enhancement of the greenhouse effect. In order to stabilise concentrations of nitrous oxide at present day levels, an immediate reduction in global emissions by 70 to 80% would be needed
The atmospheric concentration of a is a measure of the abundance of that gas in air, usually defined in terms of the proportion of the total volume that it accounts for. Greenhouse gases are trace gases in the atmosphere and are usually measured in parts per million by volume (ppmv), parts per billion by volume (ppbv) or parts per trillion (million million) by volume (pptv). Despite their very low concentrations, they have the ability to regulate the global climate, by trapping heat that would otherwise escape to space. The natural keeps the Earth's surface 33°C warmer than it should be. The of the greenhouse effect by man-made greenhouse gas including and may have caused a global warming during the of 0.6°C, with another 3°C projected to occur in the
The pre-industrial concentration of in the atmosphere was about 280 ppmv. This concentration had remained fairly constant since the end of the last Ice Age about 14.000 years ago, when it increased from 190 ppmv. Coinciding with this prehistoric rise in atmospheric carbon dioxide was a global rise in average surface temperature of 5°C. The concern today is that the increase in atmospheric carbon dioxide since the late 18th century as a result of man-made carbon dioxide is causing a further global warming. Atmospheric concentration of carbon dioxide is now about 370 ppmv, and is increasing 1.2 ppmv each year.
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