Could Space Mirrors Stop Global Warming?
In the early 2000s, Lowell Wood of Lawrence Livermore National Laboratory proposed cooling the earth by launching reflective mirrors into space, though he cautioned that the mirror should be considered only as a measure of last resort. Why? Because the mirror would have to have an area of 600,000 square miles – a slightly smaller area than Greenland – and launching something that big would be prohibitively expensive. Another option: billions of smaller mirrors. Roger Angel, researcher and optics expert at the University of Arizona, proposed that idea in 2006.
In either case, the mirror or mirrors would orbit at Lagrange point L1, a gravitationally stable point between the Earth and the sun that’s about four times the distance from the Earth to the moon. The mirrors would barely be visible from Earth and would block just 1% to 2% of the sun’s light, but that would be enough, advocates of the schemes say, to cool the planet. Even with Angel’s plan, the current cost of launching a trillion mirrors would be $10,000 per pound, or, in total, 26 times more than the current U.S. national debt.