Saturday, November 05, 2005

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, 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.


Blogger Speedracer said...

I find it amazing that you relieve yourself of any conecern or responsibility with regard to global warming with what could be described - almost literally - as a pie-in-the-sky solution to this impending crisis. Dream on, Brother...

9:24 PM  
Blogger Tom Myers said...

Wow. Communication is hard; clearly I failed, at least with "Speedracer." Well, I will go on worrying about the next few decades, you go on worrying about 2100. If anybody makes it that far (which sometimes I'm optimistic about, but not especially so this morning) then we'll see. :-) (Actually, my predictions back in 2005 for September 2011 wouldn't have been very good, either.) on

5:17 AM  
Blogger Speedracer said...

I'll admit I may have missed the point of your blog. After looking at some of the other entries, the title "Mistakes" makes sense. However, on the face of it, your entry on global warming seems to say "I don't worry about it, because we will make nano-tube sunscreens when the time comes".

1:05 AM  
Blogger Tom Myers said...

Re-reading the post, it seems to me that I didn't say I don't worry about global warming; I said I do worry about global warming -- over the next few decades, during which many bad things may happen which we should try hard to prevent or ameliorate (if we can). So my house is semi-super-insulated, as well as a quite old house can be, with geoexchange HVAC -- and I drive a hybrid, yadda yadda. What I don't worry about is long-run global warming, which I defined loosely as projected out to 2100 or 2300 or whatever. And this post is why; it was part of an argument with myself and with my brothers (one of whom is a biology prof who gives talks about small mammal ranges shifting gradually north, another is the ornithologist/environmentalist mentioned above...). I think the only thing I'd change, after six years, is that I look more favorably on a carbon tax, at least as being slightly less prone to crony-capitalism problems than the nominally equivalent cap-and-trade.

If we survive that long, and we don't actually block innovation much more than we do now, I think we certainly will be able to build nanotube sunscreens; more likely we'll be doing something else that's better, that I haven't thought of. :-)

Or then again, maybe not.

4:40 AM  

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