MORE GLOBAL WARMING PESSIMISM. I wish I shared Matt's optimism. John Quiggin's post, and Matt's, largely focuses on the ease of heavily reducing CO2 emissions within America. And on that point, Quiggin's right: to paraphrase Rob Schneider's character in nearly every Adam Sandler movie ever made, we could do it!

But we won't. The quick sketch looks like this (go here for the long version). Climatologists tend to think that we're rapidly approaching, or have already passed, a crucial tipping point at which the feedback loops and energy patterns driving global warming are simply not reversible enough, fast enough, to forestall the catastrophic climatological impact folks fear. Matt and John mention that changing patterns merely in the U.S. would kill off a couple percentage of GDP growth -- given the way conservatives fret and fear over slight increases in taxation-as-percentage-of-GDP, the likelihood that we'll institute such cuts while global warming remains a journal paper abstraction strikes me as near nil.

Worse yet is the situation of the developing world. Matt mentions that they don't already have the wasteful energy usage patterns we do. True enough. But we adopted those patterns for a reason: they're cheaper. Current predictions see 1 billion autos on the road by 2020, with growth increasing almost exponentially beyond that. Take China, which now has 24 million vehicles on the road, but by 2020 is slated to have 90-140 million. They're now the world's second largest petroleum user, with imports increasing by 75 percent between 2002 and 2004. And you try telling China, or India, or any other country that their citizens can't have access to cheap auto fleets like we do.

And the worries don't stop with the automobiles. Even now, we're learning that China's coal use was much, much larger than they let on over the past decade or so. The imperative for economic growth tends to wield more urgency than the need for responsible environmental policies. Shifting their growth patterns is going to rob them of much more than a mere percentage point in GDP, and it's going to be rather tricky for rich, developed countries to impose such caps from on high. So the basic problem is one of time: were global warming already nailing us, you might see the constituency you need for change. Given the crunch, though, my guess is you just don't have the domestic, much less international, political will to forestall climate change. And believe me, I deeply, deeply hope to be wrong about this.

--Ezra Klein