06 June 2006

global dimming

I've debated whether or not to even post on this topic, but now that the "too-realistic" Al Gore film is out and various people have commented on its efficacy as a vehicle for everything from providing a good argument for why our current climate change is human-induced, to why you should, undoubtedly, own a Mac.

The past few weeks on the BBC have been 'Climate Chaos' season, during which we hear from scientists who know about this whole thing much better than I. I watched three hour-long segments (in a row) the other night, which provided wonderful data to prove that the change in global temperature we're experiencing now is directly the result of CO2 emissions, the usual stuff.

But the middle hour was on something I hadn't heard about before: global dimming. Seems the particulate matter from carbon-derived emissions (that would be smog) goes up into the atmosphere and, much like other small normally-occuring particulates like salt, these tiny particles attract moisture and form little droplets. The thing is, there are lots of them, and they're smaller than the normally-occurring ones. This creates a mirror effect in which all of these droplets of water reflect the sun's light back at the sun, shielding the earth from its rays. The percentages are staggering--10% to 30% drop in sunlight, depending on where one is in the world.

The irony: global dimming is dampening the effects of global warming. So that the small temperature increases we've been seeing are actually way low, if we account for global dimming. The program suggested that the past few summers of high temps in Europe were largely due to their progressive emissions policies alleviating the global dimming. The likely right-wing take on this: carbon emissions aren't bad! Nature balances itself out once again!

Of course, the hundreds of thousands of avoidable deaths per year due to these particles in the air don't really come into this hypothetical right-wing argument.

But what's interesting to me is that I haven't heard about this global dimming thing before. Have I been out of it? Or is it that the political efficacy of raising this scientific issue is low for both the right and the left?

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