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Thank you for your survey of energy, pollution, development and just about everything else. You suggest that managing energy needs whilst refraining from emitting carbon dioxide will be both a hot topic and a source of international tension in the decades ahead. I know that this is conventional wisdom, but I am going to suggest a different way of looking at this.
I trained as a physicist, so I know how convincing the conventional arguments are. Plainly, the Earth is warmer than it would be if it was a shiny ball of rock, like the Moon. Greenhouse gases, chiefly water, act as a blanket at night, and evaporation soaks up heat during the day. If you add more greenhouse gases, therefore, you ought to get more warming. If you build models that reflect this process - as you point out - then you get a hotter Earth. And so you ought - that is what the model is built to show, after all. However, it assumes a one-to-one relationship between what there is to absorb and what is put into the atmosphere in order to absorb it.
The issue is really about what are called 'extinction curves'. That is, if you add something that absorbs radiation - let's say, ink in water - then how much absorption you get from an extra drop of ink depends on how much of it there is in the water already. If - say - 99% of the energy that the ink can absorb is already taken out, so the water look dark blue - then the next drop will change this total very little. If the water was completely clear, however, then the ink drop would change the amount of light that was absorbed by a lot. It would have a lot of unabsorbed light to work on.
Carbon dioxide absorbs and emits infrared light at very specific wavelengths - collectively called its 'spectrum'. If you use an energy source which uses carbon dioxide the way a light bulb uses a filament, then what comes out of it are precisely those wavelengths. A carbon dioxide laser is just such a source. Carbon dioxide that is in the air will absorb these wavelength, but not any others. It is transparent to these other wavelengths, just as it is "black" to the wavelengths that it can absorb, those in its spectrum. That means that a carbon dioxide laser is a good measure of how avidly the atmosphere mops up these wavelengths - it puts out only the infra red that carbon dioxide can absorb.
It turns out that the atmosphere is like water with a lot of ink in it: it attenuates a carbon dioxide laser to nearly nothing in a matter of kilometres. That is, adding some more carbon dioxide to the atmosphere is just like adding another drop of ink to an already-black glass of inky water. It won't have much affect, because almost all of the light has already been taken out.
I have been trying to get "chapter and verse" on where we are on the atmosphere's extinction curve. If we are at the bottom of it, then adding more carbon dioxide will have a big affect. If we are at the top - like the glass full of inky water, then adding more will have very little results. Nobody seems to know the answer. Truly, though, this matters to the debate. If we have an atmosphere which has already combed out almost all of the relevant wavelengths of infra red, so that there is essentially no more left to to absorb, then adding more carbon dioxide will make virtually no difference at all. If the infra red streams out unimpeded, for the most part, then adding more will have a big affect.
If we are at the bottom of the extinction curve, then greenhouse warming is a likely fact. If we are at the top of the curve, then it isn't. And nobody seems to know which of these is true!
A letter to Nature, Gleckler et al [Nature (439) 675 9th Feb 2006] review the impact of the 1883 Krakatoa explosion, which threw immense quantities of dust into the stratosphere. Contemporary observers noted that the result of this shading changed the climate, creating the "year without a Summer" in the Northern hemisphere and making the subsequent years noticeably cooler. The authors of this paper review the longer term impact of the eruption on the temperature of the ocean, using twelve separate and sophisticated climate models to do so. A 'cold anomaly' in the deep ocean is detectable nearly a century after the event.
If the authors are correct in this estimate, it follows that a component of - perhaps much of - the temperature change which has been observed in the second half of the Twentieth century may be attributable to the disappearance of the cooling effects of Krakatoa, and not the warming due to green house gases. Indeed, it may well be impossible to separate out these effects.
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