Every once in a while I feel despair over the fate of the planet. If you've been following climate science, you know what I mean: the sense that we're hurtling toward catastrophe but nobody wants to hear about it or do anything to avert it.
And here's the thing: I'm not engaging in hyperbole. These days, dire warnings aren't the delusional raving of cranks. They're what come out of the most widely respected climate models, devised by the leading researchers. The prognosis for the planet has gotten much, much worse in just the last few years.
What's driving this new pessimism? Partly it's the fact that some predicted changes, like a decline in Arctic Sea ice, are happening much faster than expected. Partly it's growing evidence that feedback loops amplifying the effects of man-made greenhouse gas emissions are stronger than previously realized. For example, it has long been understood that global warming will cause the tundra to thaw, releasing carbon dioxide, which will cause even more warming, but new research shows far more carbon dioxide locked in the permafrost than previously thought, which means a much bigger feedback effect.
The result of all this is that climate scientists have, en masse, become Cassandras - gifted with the ability to prophesy future disasters, but cursed with the inability to get anyone to believe them.
And we're not just talking about disasters in the distant future, either. The really big rise in global temperature probably won't take place until the second half of this century, but there will be plenty of damage long before then.
For example, one 2007 paper in the journal Science is titled "Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America" - yes, "imminent" - and reports "a broad consensus among climate models" that a permanent drought, bringing Dust Bowl-type conditions, "will become the new climatology of the American Southwest within a time frame of years to decades."
So if you live in, say, Los Angeles, and liked those pictures of red skies and choking dust in Sydney, Australia, last week, no need to travel. They'll be coming your way in the not-too-distant future.
Now, at this point I have to make the obligatory disclaimer that no individual weather event can be attributed to global warming. The point, however, is that climate change will make events like that Australian dust storm much more common.
In a rational world, then, the looming climate disaster would be our dominant political and policy concern. But it manifestly isn't. Why not?
Part of the answer is that it's hard to keep peoples' attention focused. Weather fluctuates - New Yorkers may recall the heat wave that pushed the thermometer above 90 in April - and even at a global level, this is enough to cause substantial year-to-year wobbles in average temperature. As a result, any year with record heat is normally followed by a number of cooler years: According to Britain's Met Office, 1998 was the hottest year so far, although NASA - which arguably has better data - says it was 2005. And it's all too easy to reach the false conclusion that the danger is past.
But the larger reason we're ignoring climate change is that Al Gore was right: This truth is just too inconvenient. Responding to climate change with the vigor that the threat deserves would not, contrary to legend, be devastating for the economy as a whole. But it would shuffle the economic deck, hurting some powerful vested interests even as it created new economic opportunities. And the industries of the past have armies of lobbyists in place right now; the industries of the future don't.
Nor is it just a matter of vested interests. It's also a matter of vested ideas. For three decades the dominant political ideology in America has extolled private enterprise and denigrated government, but climate change is a problem that can only be addressed through government action. And rather than concede the limits of their philosophy, many on the right have chosen to deny that the problem exists.
So here we are, with the greatest challenge facing mankind on the back burner, at best, as a policy issue. I'm not, by the way, saying that the Obama administration was wrong to push health care first. It was necessary to show voters a tangible achievement before next November. But climate change legislation had better be next.
And as I pointed out in my last column, we can afford to do this. Even as climate modelers have been reaching consensus on the view that the threat is worse than we realized, economic modelers have been reaching consensus on the view that the costs of emission control are lower than many feared.
So the time for action is now. O.K., strictly speaking it's long past. But better late than never.