Global warming is definitely real enough. I think the vast majority of well-thinking people who comprise the reality-based community, including scientists, are agreed on that.

What's not so agreed on is exactly the degree of current and anticipated warming, although most are agreed that the CAFE standards are way too weak.

Also, for the extreme trillions it would take to make something as bizarre and unfeasible as an artificial ring of particles or spacecraft around earth, we could do something that would work much more elegantly and effectively, while preserving our ability to see stars and planets in the night sky.

Furthermore, this is a subject that has been dealt with over the years by cartoonists and by scifi writers for all media.

* The old Gary Larson "Far Side" cartoon of "the Bozone Layer" which protects the rest of the solar system from the harmful effects of this planet.

*Larry Niven's Ring World. ((The Ringworld was a planet that had been reformed from a sphere into a band encircling its sun. Because the sun shone on the whole inside of the ring equally, where the inhabitants lived, the creators built an inner ring of panels linked with "rope", which revolved around the sun at just the right pace so that the alternating shadow/sunlight created day and night at just the same frequency as for the original planet.

But, getting real, I think if someone was willing to spend tens of trillions of dollars to combat global warming, they probably have many more land-based options than space-based, and probably much, much less expensive options. Check out Jay Inslee's (D-Washington) Apollo program for energy self-sufficiency and you can start on the right track.))

* Souls in the Great Machine by Sean McMullen, a scifi book which deals with the consequences of a life threatening ice age caused by a sunshade in the sky used to combat warming.

* Asimov's Foundation series - the idea was to build a giant steel shield over the entire planet. That way the light, wind and rain could all be under corporate control. Yikes, the future is now!

* Kim Stanley Robinson's The Mars trilogy. ((Niven's Ring, a habitable structure occupying the whole of the Earth's orbit, is more akin to a Dyson Sphere (first proposed in the 50s but brought into the public consciousness by the "Relics" episode of Star Trek: The New Generation) than it is to the type of terraforming project being discussed here.

Kim Stanley Robinson did something along these lines in the Mars trilogy, where he proposed stringing a bunch of reflectors in orbit around Mars to capture some of the solar radiation and direct it back to the planet to raise the temperature to a habitable degree.

In the long run, global climate control is going to be something that humans will need to have in the toolbox if the species is going to survive more than a couple of thousand years and get off this rock and into the rest of the solar system and the galaxy.

In the short term, spending trillions of dollars on what is essentially an experiment is unimaginable. First, the law of unintended consequences is liable to have major impact. Second, who's got 50 or a hundred trillion bucks floating around for this? This kind of project requires the entire economic output of the planet for a couple of years, if not decades, to be devoted to it. I can't think of many economic/political systems that can be so single minded, and the ones i can think of are not worth living in.))

And last but not least, a little humor.

Karnak the great: (holding envelope to his forehead) The answer is "dope ring."

Ed McMahon: "Dope... Ring"

(Karnak passes Ed annoyed glance before opening letter and reading the question sealed inside)

Karnak: "What's the best name for a plan to encircle the Earth in Levolor blinds to reduce global warming?"

Sue