Sunday, February 22, 2009

Why models underestimate climate change

Members of the church of climatic stability emphasize the limitations of climate simulation and modeling. It would be a fair criticism if they noted that errors go both ways; models can both under and over estimate climatic variability. Alas, that would contradict church doctrine.

Model variability is a reason to be extra cautious, especially because climate models put us pretty close to the cliff.

Unfortunately over the past ten years the models have almost always underestimated climate variability, pretty much putting us, as Dyer wrote recently, over the cliff.

Why should the models be consistently too optimistic? In theory they should err equally both ways.

Turns out this is a serious question ...
Global Warming Leading to Climate Tipping Point |

... Since the real world is so messy, climate scientists Gerard Roe and Marcia Baker turned for insight to the distinctly neater world of mathematics. Last year, they published an analysis in the journal Science arguing that climate models were skewed in the direction of underestimating the warming effect of carbon. The report reasoned that carbon emissions have the potential to trigger many changes that amplify the warming effect—water absorbs more sunlight than ice, humidity traps more heat, and so on—but few that would mitigate it. The odds, they figure, are about one in three that temperatures will rise by 4.5 degrees C (the top of the IPCC's range), but there's little chance at all that they'll rise by less than 2 degrees C. "We've had a hard time eliminating the possibility of very large climate changes," says Roe...
Reading between the lines climate modelers have been quite cautious; they chose to err towards optimism. That was probably politically wise, the church of climate stability would be even stronger had the models been more often wrongly pessimistic.

The reality is we're over the cliff. The question now is whether we can survive the landing.

America is going to have to grow up very quickly. The Dems alone can't do this. We desperately need a reformed science-based GOP, but instead we've got the Party of Limbaugh.

Are there any rationalist republicans at all?!

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