IPCC Leak: "Warming of the climate system is unequivocal"

The IntersectionBy Chris MooneyJan 22, 2007 7:20 PM


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I don't trust the British papers with their various hyperventilating "scoops" about the forthcoming IPCC Fourth Assessment Report. But the Toronto Starjust had a story that does sound realistic, reporting on what is purportedly a leaked final draft of the upcoming report's "Summary for Policymakers" section, which is always the most quoted and widely read part of the document. Assuming this Star story is accurate, there isn't much in it that's very surprising. Apparently the new report attributes recent warming more strongly than ever to human activities. That would make four in a row for the IPCC in terms of increasing the certainty level. Apparently the document also says that major climate change impacts are now becoming clearly evident (though there's no indication from the Star that changes to hurricanes are included in this). The one surprise is that sea level rise estimates have reportedly been lowered for the new report (I'm not sure why). Finally, the climate sensitivity for doubling CO2 in the atmosphere has apparently been raised: It's from 2 degrees C to 4.5 degrees C according to the Star. The previous IPCC report had gotten a sensitivity range from 1.7 to 4.2 degrees C.

(Note: The way the Star describes the new report's treatment of the climate sensitivity is confusing, and I may be misreading here.)

Assuming all of this is accurate, the bottom line is that the problem not only exists and persists but, predictably, continues to worsen. Between now and the fifth IPCC report, some major steps must--and, I predict, will--be taken to to try to stave off the worst of climate change. Meanwhile, barring some radical change of positioning in the State of the Union speech tomorrow, the IPCC report may well generate a feeding frenzy in which journalists and foreign governments alike pester the Bush administration, demanding to know why more is not being done..... Or maybe the Star report is completely inaccurate. We'll see.

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