Purdue University climatologist Matthew Huber gets plenty of death threats, but that hasn't stopped him from exploring the outer limits of just how much global warming human beings can tolerate. Whatever our recent Great American Heat Wave may or may not portend, most credible climate scientists agree that human-caused global warming is real -- oh yes they do! [PDF] -- and most of the research out there, Huber says, predicts dire consequences for people (and other mammals) if average global temperatures rise by 6 degrees C or more.
That could well happen this century: By 2100, Huber points out, the mid-range estimates predict a rise of 3 to 4 degrees C in average global temperatures based on current economic activities, but those studies ignore accelerating factors like the release of vast quantities of methane -- a potent greenhouse gas -- now trapped beneath permafrost and sea ice that's becoming less and less permanent. Other models foresee rises in the 10 degrees C range this century; at the outer fringe, predictions range as high as 20 degrees C. Truth is, we simply don't know exactly when we'll reach these milestones or what they will cost us. And thanks to the uncertainty, it's been hard to get nations to agree on limits.
All of this got Huber and Steven Sherwood, his colleague at Australia's University of New South Wales, to thinking: Economic considerations aside, they asked, how much warming can we physiologically tolerate? At what point does it get so bad that our bodies can no longer keep cool, so bad that we can no longer work or play sports or even survive for long out of doors? Will we flee for colder climes? Live underground like hobbits, surviving on cold fungus? Okay, I'm projecting -- they didn't actually ponder that last bit that I'm aware of.