Sunday, February 18, 2007

Cooling the Planet, and Excuse Slips from War

Back in November 2005, I commented on Long Run Global Warming and Other Things I Don't Worry About, saying that long before 2100 we'll be able to turn the heat up or down as we wish, e.g. with a solar shade at the Lagrangian point L1 which could just stop the light or could redirect it via Fresnel lens. I am thoroughly unsurprised to find that this particular suggestion had been made long before; Technology Review reports that

But in 1989, James Early of the Lawrence Livermore National Laboratory noted the harbingers of global warming and proposed deflecting a measure of sunlight with a "space shade" located at Lagrangian Point L1--an orbit 1.5 million kilometers up, where Earth's gravity and that of the Sun are balanced so an object can remain stationary relative to both bodies. How big a shield was Early thinking about? One 2,000 kilometers in diameter and about 10 microns thick, with a weight of about 100 megatons under Earth's gravity. Early's shield would have been either opaque or else transparent in the form of a Fresnel lens...

Of course, the nanotube sheets I mentioned would make that easier (though I'm not sure how thin you can make a Fresnel lens; I think that thickness is irrelevant as long as the bands defining reflection and transmission are the right diameters, but I haven't actually passed a test on those equations since sophomore physics in Buenos Aires, back in 1970.) The current Technology Review isn't really talking about Early's work, it's talking about a plan to put dust (well, little bits of diatomaceous earth) in the stratosphere. That could work, but I still think that my Solar Silver Bullet will (in a couple of decades; maybe one) be better: we will be able to put half-silvered hydrogen balloons in the stratosphere with Stirling engines at the focal points of the half-silvering, and the balloons will collect solar energy (in the form of hydrogen, probably, to be compressed and sent to ground level) rather than just passively blocking it. Probably we'll have something still better, something that I haven't thought of, but I think we'll have something at least that good. (Maybe the balloons will store the energy in the form of ammonia or aluminum; maybe they'll be gigantic, and will beam it down to central collection points...maybe they'll be in space after all. But they will be able to collect power as well as block it.) So when Tom Barnett columnizes that "We didn't leave the Stone Age because we ran out of stones, and we won't leave the Oil Age because we've run out of oil." I basically agree; the price of oil is likely to rise quite a bit as we find replacements, but the replacements exist and will be cheaper in the end, we will not be running out. And I've got to admit my own vulnerability to his central charge that

Given our love of technology, it's no surprise that science, our modern god-machine, is viewed as our most likely salvation and/or curse: the right new gizmo renders this entire fight unnecessary or some looming disaster makes it entirely pointless.

The trouble is, that new gizmos do empower people both good and bad, and they do increase connectivity both good and bad. Therefore, they do good things but also they make terrorists more powerful and bring them close up, and that's what I've been describing as our Long War problem with a multi-part solution. Of course Barnett is not concerned with me; I'm not an important audience. He's concerned with (and replying to) the people who want an "excuse slip" from the war, and want to base it on technology. And as usual, mostly I agree.

But Barnett sees himself as a Grand Strategist who thinks across decades; I don't really believe him, because I see him as missing the central role of Moore's Law. Hmmm.


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