interceptor

Novas mensagens, análises etc. irão se concentrar a partir de agora em interceptor.
O presente blog, Geografia Conservadora servirá mais como arquivo e registro de rascunhos.
a.h

Monday, April 30, 2007

A hipótese e a infalibilidade dogmática

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Now imagine two lines on a piece of graph paper. The first rises to a crest, then slopes sharply down, then levels off and rises slowly once more. The other has no undulations. It rises in a smooth, slowly increasing arc. The first, wavy line is the worldwide CO2 tonnage produced by humans burning coal, oil and natural gas. On this graph it starts in 1928, at 1.1 gigatons (i.e. 1.1 billion metric tons). It peaks in 1929 at 1.17 gigatons. The world, led by its mightiest power, the USA, plummets into the Great Depression, and by 1932 human CO2 production has fallen to 0.88 gigatons a year, a 30 per cent drop. Hard times drove a tougher bargain than all the counsels of Al Gore or the jeremiads of the IPCC (Inter-Governmental Panel on Climate Change). Then, in 1933 it began to climb slowly again, up to 0.9 gigatons.
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And the other line, the one ascending so evenly? That's the concentration of CO2 in the atmosphere, parts per million (ppm) by volume, moving in 1928 from just under 306, hitting 306 in 1929, to 307 in 1932 and on up. Boom and bust, the line heads up steadily. These days it's at 380.There are, to be sure, seasonal variations in CO2, as measured since 1958 by the instruments on Mauna Loa, Hawai'i. (Pre-1958 measurements are of air bubbles trapped in glacial ice.) Summer and winter vary steadily by about 5 ppm, reflecting photosynthesis cycles. The two lines on that graph proclaim that a whopping 30 per cent cut in man-made CO2 emissions didn't even cause a 1 ppm drop in the atmosphere's CO2. Thus it is impossible to assert that the increase in atmospheric CO2 stems from human burning of fossil fuels.
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As Hertzberg readily acknowledges, the carbon dioxide content of the atmosphere has increased about 21 per cent in the past century. The world has also been getting just a little bit warmer. The not very reliable data on the world's average temperature (which omit most of the world's oceans and remote regions, while over-representing urban areas) show about a 0.5Co increase in average temperature between 1880 and 1980, and it's still rising, more sharply in the polar regions than elsewhere. But is CO2, at 380 parts per million in the atmosphere, playing a significant role in retaining the 94 per cent of solar radiation that's absorbed in the atmosphere, as against water vapor, also a powerful heat absorber, whose content in humid tropical atmosphere, can be as high as 2 per cent, the equivalent of 20,000 ppm. As Hertzberg says, water in the form of oceans, clouds, snow, ice cover and vapor "is overwhelming in the radiative and energy balance between the earth and the sun Carbon dioxide and the greenhouse gases are, by comparison, the equivalent of a few farts in a hurricane." And water is exactly that component of the earth's heat balance that the global warming computer models fail to account for.
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