Boy are we screwed!

Bill McKibben: Civilization's last chance

All of a sudden it isn't morning in America, it's dusk on planet Earth.

There's a number -- a new number -- that makes this point most powerfully. It may now be the most important number on Earth: 350. As in parts per million of carbon dioxide in the atmosphere.

A few weeks ago, NASA's chief climatologist, James Hansen, submitted a paper to Science magazine with several coauthors. The abstract attached to it argued -- and I have never read stronger language in a scientific paper -- that "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm."

Hansen cites six irreversible tipping points -- massive sea level rise and huge changes in rainfall patterns, among them -- that we'll pass if we don't get back down to 350 soon; and the first of them, judging by last summer's insane melt of Arctic ice, may already be behind us.

So it's a tough diagnosis. It's like the doctor telling you that your cholesterol is way too high and, if you don't bring it down right away, you're going to have a stroke. So you take the pill, you swear off the cheese, and, if you're lucky, you get back into the safety zone before the coronary. It's like watching the tachometer edge into the red zone and knowing that you need to take your foot off the gas before you hear that clunk up front.

In this case, though, it's worse than that because we're not taking the pill and we are stomping on the gas -- hard. Instead of slowing down, we're pouring on the coal, quite literally. Two weeks ago came the news that atmospheric carbon dioxide had jumped 2.4 parts per million last year -- two decades ago, it was going up barely half that fast.

And suddenly the news arrives that the amount of methane, another potent greenhouse gas accumulating in the atmosphere, has unexpectedly begun to soar as well. It appears that we've managed to warm the far north enough to start melting huge patches of permafrost, and massive quantities of methane trapped beneath it have begun to bubble forth.