http://science.slashdot.org/article.pl?sid/06/27/2244227&threshold=2&tid0&tid
"Space Ring Could Combat Global Warming" I'll have to admit to having noodled around this very same proposal myself. But here's what I think nowadays. When it comes to reversing the effects of global warming, blocking the sun to cool things is a very short lever. Reducing the amount of extra CO2 that we're dumping into the atmosphere every day is a very long lever. And it occurs to me that even $500 billion could pay for a good deal of SPS development. Having spent that much, I think we'd be to a point where a significant number of old fossil-fuel plants were being retired and not replaced with new fossil-fuel plants. There was a discussion on one of the space newsgroups where someone asked about an SPS system at the Earth-Sun L-1 point which would block light from striking the poles. I explained that an object at that distance from the Earth would have a penumbra much bigger than the Earth, so one couldn't talk about selectively shading one area of the Earth versus another. I also opined that the energy coming from the system would do far more to help the situation that the relatively modest amount of shading we'd get out of it. But it later occurred to me that one reason why I was attracted to a closer sunshade when I was day-dreaming on this topic was because I wanted to selectively shade the equatorial regions. My reasoning was that a bit of warming at lower and higher latitudes might be a good thing, as long as we could balance it by cooling the tropics. But here this guy was talking about selectively shading the poles. And I realized that he was thinking about preventing the rise in ocean levels which we'll have from increased melting at the poles. And in truth, that will probably be one of the most economically-harmful effects of global warming.
Regards,
Mike Combs
