Bruce McQuain, writing at Hot Air, has a great post up, Former “alarmist” scientist says Anthropogenic Global Warming, (AGW) based in false science, excerpting portions of comments made recently by David Evans. Evans is a scientist who formerly "consulted full-time for the Australian Greenhouse Office (now the Department of Climate Change) from 1999 to 2005," "“in the heart of the AGW machine." Evans is "a scientist who was on the carbon gravy train, understands the evidence, was once an alarmist, but am now a skeptic."
As Evans explains, the official climate model is based on the following core idea:
For each bit of warming due to carbon dioxide, they claim it ends up causing three bits of warming due to the extra moist air. The climate models amplify the carbon dioxide warming by a factor of three — so two-thirds of their projected warming is due to extra moist air (and other factors); only one-third is due to extra carbon dioxide.
However, "The alarmist case is based on this guess about moisture in the atmosphere, and there is simply no evidence for the amplification that is at the core of their alarmism." This had become clear in the mid-1990s as a result of data from thousands of weather balloon measurements in the late '70s, '80s, and '90s.
Evans concludes, quite perceptively:
We are now at an extraordinary juncture. Official climate science, which is funded and directed entirely by government, promotes a theory that is based on a guess about moist air that is now a known falsehood. Governments gleefully accept their advice, because the only ways to curb emissions are to impose taxes and extend government control over all energy use. And to curb emissions on a world scale might even lead to world government — how exciting for the political class!