6.1. 1: The Natural Greenhouse Effect
There is little argument that global levels of Carbon dioxide are rising, and that the majority of the population link the rise in Carbon Dioxide levels to the issue of Global Warming through the “greenhouse effect”. However to large swathes of the populace the idea that the Greenhouse effect is in essence the natural state of our atmospheric systems is badly misunderstood in the least.
The earth is warmed by incoming solar radiation that is then either reflected directly back to space or absorbed then returned as long wave thermal radiation (infrared). If this occurred as a simple exchange then the Earths average temperature would be around 25oC lower than the global average of 15oC.
The reason for the higher than expected average global temperature is the existence of greenhouse gases in the atmosphere. Nitrogen and oxygen form around 99% of the atmospheric cocktail yet neither gas can absorb or radiate thermal radiation. However some gases in the remaining 1% can. These include Carbon dioxide, water vapour,methane and nitrous oxides in the troposphere as well as as stratospheric ozone to an extent.