George Will writes today that any attempts to avert large-scale global warming would be absurdly expensive, while the "positive impact on the globe's temperature [would be] insignificant." He's also discovered--shockingly--that California can't reduce the world's CO2 emissions all by itself. So there you have it: No use trying. Nothing we can do. Give Bangladesh our regards.

Would it be too much to ask Will to offer numbers here? Yes, it would. (Although he does rattle off a bunch of facts about zinc mining in Canada.) Fortunately, though, Reuters just got its mitts on a leaked copy of the forthcoming IPCC report on mitigation--which deals with this exact subject--so we can put this discussion in context. The IPCC plans to report that it is perfectly possible to prevent global average temperatures from rising more than 2 degrees C (the "dangerous" threshold). It would cost about 3 percent of global GDP--roughly one year's worth of economic growth. Not cheap, but not exactly undoable, either.

Maybe Will would say that a year's worth of economic growth is still too high a price to pay. Or maybe he would start arguing about discount rates and the like. But why not have that debate, rather than rambling on about Ben & Jerry's and then accusing environmentalists of "fuzzy climate math"?

--Bradford Plumer