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Comment Dated Dec 18, 2006
I refuse to get worried over the hysteria currently engulfing the planet on the subject of global warming--or as it has now been renamed, "climate change." The Earth's climate has always been changing in one direction or another, and always will be. The 1930s were relatively warm, with ice thinning and lots of open water in the Arctic regions--pretty similar to what's being reported now--accompanied by grim prophecies of the world would end if the trend were to continue unabated in the way that such trends never do. Then, around 1940, a mild cooling set in until the early 70s, by which time the headlines were blaring predictions of doom by freezing, and Lowell Ponte had a huge best-seller called The Cooling: Has the new ice age already begun? Can we survive? But the cooling reversed to become a mild warming again, and the last few years seem to have shown anything from no significant change to what could be the beginnings of a decline again, depending whom you listen to.
What do we know as a fact at the end of it all? That in the course of the 20th century, the mean temperature of the Earth increased by about 0.6 of a degree C, practically all of it before 1940, and despite all the claims and hype, nobody really knows why. It's not something I'm going to lose any sleep over.
The chant is that it's due to human industry and other activities, but apart from preconceptions there's little to back that up. There were comparable warm periods in the medieval era around 1100 A.D., when the Vikings had settlements in Greenland, in the Roman Period, and a far greater one before 2,000 B.C., that had nothing to do with ox roasts and pottery kilns. Yes, atmospheric CO2 also increased appreciably in the same century; but almost all of it took place in the decades following 1950, when the warming it was supposed to have caused had already happened. And reconstructions of data from earlier cycles shows the same pattern of the warming occurring first, and an increase in CO2 following. This is consistent with many known mechanisms by which a mild increase in temperatures would release large amounts of carbon from reservoirs in oceans and Arctic regions. In any case, 95 percent or so of the "greenhouse effect" that keeps the Earth 33 degrees warmer than it would otherwise be at this distance from the Sun is due to water vapor, which the scare stories omit to mention. You can't regulate it, tax it, or blame it on the usual suspects.
Another inconvenient truth that escapes mention is that what warming there is appears to be Solar-System-wide, affecting Mars, Jupiter, Saturn, Neptunes' moon Triton, and Pluto. For summary reviews see, for example, here and here. Maybe it's proof that power plants and cement factories are affecting the Sun.
Natural variations in cosmic phenomena and their likely effect on our climate anytime soon don't worry me. What does concern me is the damage to the human condition and the general quality of life that can result from politically motivated misrepresentations of science and policymaking being stampeded by sensationalism. I'm not sure which represents the greater menace: politicians who subject matters of objective truth to the same methods they use in waging election campaigns; or ex-scientists meddling in politics, who have convinced themselves they're crusading to save the world.