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Climate Science In Denial
...The IPCC’s position in its Summary for Policymakers from their Fourth Assessment (2007) is weaker, and simply points out that most warming of the past 50 years or so is due to man’s emissions. It is sometimes claimed that the IPCC is 90% confident of this claim, but there is no known statistical basis for this claim—it’s purely subjective. The IPCC also claims that observations of globally averaged temperature anomaly are also consistent with computer model predictions of warming.

There are, however, some things left unmentioned about the IPCC claims. For example, the observations are consistent with models only if emissions include arbitrary amounts of reflecting aerosols particles (arising, for example, from industrial sulfates) which are used to cancel much of the warming predicted by the models. The observations themselves, without such adjustments, are consistent with there being sufficiently little warming as to not constitute a problem worth worrying very much about.

In addition, the IPCC assumed that computer models accurately included any alternative sources of warming—most notably, the natural, unforced variability associated with phenomena like El Nino, the Pacific Decadal Oscillation, etc. Yet the relative absence of statistically significant warming for over a decade shows clearly that this assumption was wrong. Of course, none of this matters any longer to those replacing reason with assertions of authority.

Consider a letter of April 9 to the Financial Times by the presidents of the U.S. National Academy of Science and the Royal Society (Ralph Cicerone and Martin Rees, respectively). It acknowledges that climategate has contributed to a reduced concern among the public, as has unusually cold weather. But Messrs. Cicerone and Rees insist that nothing has happened to alter the rather extreme statement that climate is changing and it is due to human action. They then throw in a very peculiar statement (referring to warming), almost in passing: “Uncertainties in the future rate of this rise, stemming largely from the ‘feedback’ effects on water vapour and clouds, are topics of current research.”

Who would guess, from this statement, that the feedback effects are the crucial question? Without these positive feedbacks assumed by computer modelers, there would be no significant problem, and the various catastrophes that depend on numerous factors would no longer be related to anthropogenic global warming.

That is to say, the issue relevant to policy is far from settled....