Global Warming - A Coolist's View - Printable Version
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Global Warming - A Coolist's View - Sunsettommy - 01-13-2012 06:22 PM
Anthropogenic Global Cooling
The global warming concept hinges upon the idea that greenhouse gasses cause an increase in mean global temperatures. The basis for this concept is that such gasses are better radiators than non greenhouse gasses and as a result keep the global mean temperatures higher as a result of feeding back radiation to the Earth's surface. Let us investigate this hypothesis:
First of all we need a model upon which all can agree is a good approximation to the real thing. The model I have chosen is familiar to most engaged in the debate and in my view lies closest to the hearts of the so-called global warmists. In this model we are concerned only with radiation from the sun which interacts thermally with the Earth's surface and atmosphere. We are not concerned with radiation that is reflected either specularly or diffusely back into the space from which it came. Neither are we concerned about radiation which is absorbed and re-emitted without intermediate thermal processes. Without such processes there can be no warming of the Earth's surface and atmosphere so such non thermal interactions can be neglected.
Removing such non thermal processes from our model leaves us with this: the Earth's surface is treated as an approximation to a black-body, it absorbs radiation from the sun, becomes hotter and then re-emits radiation more typically at longer wavelengths. We also have an atmosphere which is composed of two types of gas: greenhouse gasses and non greenhouse gasses, both of which may or may not absorb and re-emit radiation or receive thermal input via convection and conduction from the Earth's surface as is their wont. It does not concern us for now as to the nature of these processes.
To further the debate we have the concept propounded by the pro-greenhouse warming lobby that because greenhouse gasses are better radiating gasses than non greenhouse gasses they re-radiate more radiation back to the Earth's surface than do non greenhouse gasses. This leads us to an obvious thought experiment: