Thursday, June 20, 2013

Cooling, but misstated, consensus

Will Wilkinson in The Economist writes about global warming not proceeding as fast as expected: "A Cooling Consensus." Excerpt:
We have not been awash in arguments for adaptation precisely because the consensus pertained to now-troubled estimates of climate sensitivity. The moralising stridency of so many arguments for cap-and-trade, carbon taxes, and global emissions treaties was founded on the idea that there is a consensus about how much warming there would be if carbon emissions continue on trend. The rather heated debates we have had about the likely economic and social damage of carbon emissions have been based on that idea that there is something like a scientific consensus about the range of warming we can expect. If that consensus is now falling apart, as it seems it may be, that is, for good or ill, a very big deal. 
Me: The key consensus was, and is, that global warming is happening; is anthropogenic; and carries serious risks. Often, this has been expressed in terms of projected temperature ranges. It is not the case that we know how much warming there will be, and it is not the case that carbon taxes or other measures would only make sense if we did know. A great virtue of carbon pricing, in fact, is that it can be adjusted as new information comes in about the extent and effects of warming.

Wilkinson is right* that some people have overstated the certainty of disaster if we don't keep atmospheric carbon to certain levels (e.g., "Global Warming's Terrifying New Math"). But for years we've been hearing from the other side of the "debate" that global warming is not happening, not anthropogenic or nothing to worry about (hey, good for plants, even). Two of those propositions are false, and the third is still dubious. If, as many scientists believe, the oceans are absorbing much of the warming, with the result being rising sea levels, then a do-nothing policy is still dangerous. I'll add that the case for a carbon tax is not solely dependent on global warming but also draws on other environmental, fiscal and national-security considerations. Having said all that, you'll never hear me argue against adaptation as part of the strategy. Given the politics involved, we'll need it.

* UPDATE 1:23 PM: Rereading what I wrote, I'd amend the last paragraph to take out the opening words "Wilkinson is right that..." as the subsequent point, though relevant, is not something Wilkinson asserted.

UPDATE 6/23: These posts by Greg Laden make good explanatory points:
--"The Ocean is the Dog. Atmospheric Temperature is the Tail."
--"Why you sound so stupid when you say 'global warming has stopped'."

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