Long-Run Global Warming and Other Things I Don't Worry About
I do take global warming seriously. I didn't do so, back when my elder brother the ornithologist/environmentalist explained it to me in the early 80s, and I was right not to do so but wrong about the outcome -- as a very junior comp-sci professor I was familiar with the reality of global warming effects and global cooling effects, and they're both real but the models were not then worth taking seriously. Now they are. Okay, and I worry a bit -- not panicking, but worrying -- about the high probability of major habitat loss and species shift and species loss over the next few decades, with a low probability of something big like ocean currents changing substantially in a short (several-year?) span. That's bad and we should try to minimize the foreseeable problems. But I don't worry about degrees C or F projected out to 2100 or 2300 or whatever.
My reason? If we make it to 2100, which we might not, then we will cool or warm the biosphere to whatever extent we want. Consider, just as one possibility which couldn't reasonably have been foreseen (by me, anyway) a few years ago, the new carbon nanotube sheets which "can be made so thin that a square kilometer of solar sail would weigh only 30 kilograms." Okay, what I want is, umm, a circle of solar sail at L1, the Lagrangian point that's about a million miles from us towards the Sun. If that circle is two Earth-diameters in diameter, then we'll be completely in its shadow: just imagine the similar triangles with apex at L2, a million miles in the other direction. (The Sun's diameter is 100x Earth's, and the Sun is 100x as far away as L1, so the Earth-diameter:L2-distance triangle of our shdow is similar to the 2x-EarthD:(L1+L2-distance) which is similar to the (SunDiameter:SunDistance) triangle.) My solar sail (parasol?) has radius 10K kilometers so its area is 314 million square kilometers so it weighs 10 billion kilograms or 10 million metric tons. Granted, the current version is described as transparent, but long before 2100 we will be able (with addtional weight) to set it up as a Fresnel lens to redirect or as a solar cell to extract whatever part of the energy (just a few thousand terawatts?) we feel like using for launching interstellar transport or turning Jupiter into a Ringworld or whatever. (The parasol will use a little of the energy to maintain its own stability.)
So, when somebody wants me to worry about the melting of the arctic tundra or retreat of too many glaciers and stuff like that, I'll worry somewhat. I won't support Kyoto, but I'll worry -- and I will support expenditures on more research, on geoexchange HVAC, on plug-in hybrids, bladerunner trucks, and so on. I'll even support an oil tax, though not a carbon tax. When somebody wants me to worry about 2100...no, sorry. That's like asking a Roman in 0AD to worry about 2000AD, except that the Roman had a good excuse for not foreseeing exponential increase in technical progress, so he might think he had something useful to say about planning that far ahead.
UPDATE 2006-09-27: The Toronto Sun says
Manipulating our entire environment with giant orbiting mirrors to undo man-made damage may sound like science fiction. But it's not Dr. Roger Angel believes it's time to turn on Earth's AC. Imagine a world where trillions of sunshades orbit above us. Where a huge mirror stands between our planet and the sun.and he's right. Well, it's time to work on it.