Blocking The Sun For $100 Billion a Year

The graphic shows the 2 foot-diameter flyers at L1. They are transparent, but blur out transmitted light into a donut, as shown for the background stars. The transmitted sunlight is also spread out, so it misses the Earth. This way of removing the light avoids radiation pressure, which would otherwise degrade the L1 orbit. (Illustration: Courtesy of UA Steward Observatory)I was reading an article in a local paper today about possible temporary solutions to global warming when I was reminded of something I had seen late last year from a professor at Arizona University.  We've all heard some decent ideas over the years about how we can combat the global climate change that many scientists are warning us about (anybody else remember the Global Cooling scares in the mid-70's?), but I think this one is the most subtle of dangerous plans.

Dr. Roger Angel has proposed the deployment of a large sunshade for the Earth, made up of trillions of small free-flying spacecraft about a million miles from Earth in what's referred to as the L1 orbit.  This would create a sort of cloud that would block approximately 2% of the sunlight that reaches the planet, which would in turn cool the globe due to the reduced solar energy.

I'll admit that blocking the sun partially will help reduce the warming that has gone on for the last quarter century, but will this actually help buy the citizens of Earth some time to adopt cleaner industries and practices?  I think this would create a few problems:

  1. fast moving debris in our orbit (already a problem for our Low Earth Orbit equipment)

  2. objects that block ground-based or LEO (Low Earth Orbit) scientific instruments aimed in the general direction of the sun

  3. another reason why humans can ignore the damage we cause to the environment (the hotter it gets, the more little filters we send up)

This would also create a nightmare for anyone that had to clean this up if our technology ever progressed to the point where we could terraform the planet and remove any unwanted elements from our atmosphere (and reconstruct the ozone, of course).  The initial design calls for these machines to be about 1/5000 of an inch thick, so they could be directed to fall back towards our atmosphere where they would burn up ... but then this might cause some ecological damage depending on the materials used.

I agree that we humans need to have a more active role in preventing drastic global climate change (be it warming or cooling), but I fear that temporary band-aid technologies such as this will only make matters worse.  We are a very industrious, but lazy people.  If we can leave the hard decisions to our children, or our children's children, we will.  That's just the nature of the beast.  All over the world we see examples of governments making seemingly poor decisions about our future while lining the pockets of big business and personal aquaintences.

If Dr. Angel's plan could truly be performed as a temporary solution (no more than 50 years or so), then it's a valid option that we could employ while industry and the world in general switches to cleaner technologies and the atmosphere is scrubbed of damaging chemicals.  My fear is that world governments would decide to continue sending more of the shields into space until they almost completely block our sky.