When it comes to global warming, however, [moving by increments] is precisely why we’re headed off a cliff, why the Copenhagen talks that open this week, almost no matter what happens, will be a disaster. Because climate change is not like any other issue we’ve ever dealt with. Because the adversary here is not Republicans, or socialists, or deficits, or taxes, or misogyny, or racism, or any of the problems we normally face — adversaries that can change over time, or be worn down, or disproved, or cast off. The adversary here is physics.
Physics has set an immutable bottom line on life as we know it on this planet. For two years now, we’ve been aware of just what that bottom line is: the NASA team headed by James Hansen gave it to us first. Any value for carbon dioxide (CO2) in the atmosphere greater than 350 parts per million is not compatible “with the planet on which civilization developed and to which life on earth is adapted.” That bottom line won’t change: above 350 and, sooner or later, the ice caps melt, sea levels rise, hydrological cycles are thrown off kilter, and so on.
And here’s the thing: physics doesn’t just impose a bottom line, it imposes a time limit. This is like no other challenge we face because every year we don’t deal with it, it gets much, much worse, and then, at a certain point, it becomes insoluble — because, for instance, thawing permafrost in the Arctic releases so much methane into the atmosphere that we’re never able to get back into the safe zone. Even if, at that point, the U.S. Congress and the Chinese Communist Party’s Central Committee were to ban all cars and power plants, it would be too late.
Oh, and the current level of CO2 in the atmosphere is already at 390 parts per million, even as the amount of methane in the atmosphere has been spiking in the last two years. In other words, we’re over the edge already. We’re no longer capable of “preventing” global warming, only (maybe) preventing it on such a large scale that it takes down all our civilizations.
So here’s the thing: When Barack Obama goes to Copenhagen, he will treat global warming as another political problem, offering a promise of something like a 17% cut in our greenhouse gas emissions from their 2005 levels by 2020. This works out to a 4% cut from 1990 levels, the standard baseline for measurement, and yet scientists have calculated that the major industrialized nations need to cut their emissions by 40% to have any hope of getting us on a path back towards safety.
