Discussion site:
http://science.slashdot.org/article.pl?sid/06/27/2244227&threshold=2&tid0&tid

"Space Ring Could Combat Global Warming
Space
Science
Posted by timothy on Monday June 27, @...
from the pie-plate-in-the-sky dept.
telstar writes "Though the debate continues around global warming, a new
proposal suggests building an artificial space ring around the Earth to
block the light of the sun and bring a balance to solar radiation, cloud
cover, and heat-trapping greenhouse gases. The ring could be comprised
of particles which would scatter the sunlight, or be built by an
interconnected ring of spaceships aligned to block the light. The former
proposal is estimated to cost anywhere from $6 trillion to $200 trillion
dollars, while the spaceship solution would run approximately $500
billion. Halo fans rejoice." "

Links to:
http://www.livescience.com/technology/050627_warming_solution.html
From that article:
============

A wild idea to combat global warming suggests creating an artificial
ring of small particles or spacecrafts around Earth to shade the tropics
and moderate climate extremes.

There would be side effects, proponents admit. An effective
sunlight-scattering particle ring would illuminate our night sky as much
as the full Moon, for example.

And the price tag would knock the socks off even a big-budget agency
like NASA: $6 trillion to $200 trillion for the particle approach.
Deploying tiny spacecraft would come at a relative bargain: a mere $500
billion tops.

But the idea, detailed today in the online version of the journal Acta
Astronautica, illustrates that climate change can be battled with new
technologies, according to one scientist not involved in the new work

...

"I don't think that the modest warming trend we are currently
experiencing poses any significant or long-term threat," Peiser told
LiveScience. "Nevertheless, what the paper does show quite impressively
is that our hyper-complex civilization is theoretically and
technologically capable of dealing with any significant climate change
we may potentially face in the future."

Peiser also notes that the Kyoto Protocol, a global agreement to reduce
greenhouse gas emissions, is estimated to cost the world economy some
$150 billion a year. He also sees a broader rationale for supporting the
seemingly bizarre manner of managing Earth's temperature budget.

"I believe that this mindset, despite its apparent eccentricity, is
actually rather reassuring," Peiser said. "It provides concerned people
with ample evidence of the extraordinary human ingenuity that, as so
often in the past, has helped to overcome many predicaments that were
regarded as impenetrable in previous times."

He also sees an ultimate big-picture reasoning to look favorably on the
notion of controlling Earth's climate.

"Whatever the cost and regardless of whether there is any major risk due
to global warming," Peiser said, "it would appear to me that such a
space-based infrastructure will evolve sooner or later, thus forming
additional stepping stones of our emerging migration towards outer space."
=========

Just FYI.

--Paul Fernhout

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