"I don't think the American public has gripped in its gut what could happen," he said. "We're looking at a scenario where there's no more agriculture in California." And, he added, "I don't actually see how they can keep their cities going" either.
I think Chu can be criticized for not choosing his off-the-cuff comments more carefully. He should know that people whose work generally aided the side that's trying to delay action to reduce emissions will choose to interpret him as saying there will be not a single occupied city or farm in California in 2100. Note they will also ignore his qualifier that devastation could occur only "if Americans [and others, presumably] do not act to slow the advance of global warming." In other words, a business-as-usual scenario that goes far past a doubling of CO2 levels in 2100.
Cue Jonathan Adler and Roger Pielke Jr. to go the literal route, ignore the qualifier and ignore the real point that California agriculture will be devastated and cities disrupted to the point where some will be virtually uninhabitable. The thread at Stoat covers basic points in support of Chu: the snowpack stores half the needed water, change from snow to rain lowers existing reservoir capacity, and building thousands of small new dams or a few giant dams is impractical and has its own environmental impacts. I'll add that we're also going to lose a lot of Colorado River water (something Pielke might have realized), that 5C degree increase (or more) will require more water for farming and landscaping than current temps, more people in many cities means more water demand, and that salt water intrusion will screw up coastal and Sacramento Delta agriculture.
I'll also add that skeptics should go to Fresno, Bakersfield, or God-help-you Barstow on a record-hot summer day, imagine it 5C warmer and describe whether people will choose to live there (remember we're talking about more than 2xCO2 levels). And it's not like those cities have pleasant, Phoenix-style winter climates.
But for a policy type like Pielke to say the off-hand comment by Chu is "exactly the same thing" as the abuse of science by Bushies is truly rich. I wouldn't complain all that much about Bush if that was all he did, instead of cutting access to contraceptives and sex education, shutting down stem cell research, and trying to reduce earth observation satellite programs.
Extra stuff: Adler provides a useful link here to California impacts. Note the effect of losing "chill hours" on agriculture, among other issues.
More extra: James says he likes this Pielke Jr. post. Let's see what James ends up posting about it.