Reduce Global Warming By Blocking Sunlight

At a conference last year on global warming, distinguished astrophysicist and sf author Gregory Benford pointed out that the various measures proposed to stop global warming will not do the job soon enough.

So, he has a radical proposal - build a concave Fresnel lens 1,000 kilometers across but only a few millimeters thick, and place it at the L1 orbital point between ourselves and the Sun. This would slightly reduce the total amount of sunlight to fall upon the Earth and cool us down enough to offset our greenhouse gas production.

Benford's credentials are impressive; he is a professor of plasma physics and astrophysics at the University of California, and has been an adviser for NASA, the Department of Energy and the White House Council on Space Policy. He believes that the project could be completed with current technology for a cost of about $10 billion up front, and another $10 billion over its lifespan.

The lens would be spun to help it maintain its shape; it would need thrusters around its rim to keep it from drifting away and spin it up to speed.

This is not the first time this kind of idea has been proposed, although in different circumstances. Arthur C. Clarke used a similar idea in his 1953 novel Childhood's End when it became necessary for the Overlords to discipline an entire country:

There had also been some passive resistance to the policy of the Overlords. Usually, Karellen had been able to deal with it by letting those concerned have their own way, until they had discovered that they were only hurting themselves by their refusal to co-operate. Only once had he taken any direct action against a recalcitrant government.

For more than a hundred years, the Republic of South Africa had been the centre of social strife... When it became clear that no attempt would be made to end discrimination, Karellen gave his warning. It merely named a date and time-no more. There was apprehension, but little fear or panic, for no-one believed that the Overlords would take any violent or destructive action which would involve innocent and guilty alike.

Nor did they. All that happened was that as the sun passed the meridian at Cape Town-it went out. There remained visible merely a pale, purple ghost, giving no heat or light. Somehow, out in space, the light of the sun had been polarized by two crossed fields so that no radiation could pass. The area affected was five hundred kilometres across, and perfectly circular.

The demonstration lasted thirty minutes. It was sufficient: the next day the Government of South Africa announced that full civil rights would be restored to the white minority.

Take a look at more than two dozen original science fiction ideas and inventions from the work of Arthur C. Clarke. Read more at Astroengineering global warming. Scroll down for more stories in the same category. (Story submitted 4/10/2005)