Gregory Benford, a science fiction author and professor of plasma physics and astrophysics at the University of California, has introduced a plan to stop global warming. Benford and many other scientists believe something has
to be done to stop global warming before it reaches a catastrophic no-turning-back point.
Gregory Benford's idea is to build a concave Fresnel Lens 1000 kilometres
across but only a few millimetres thick at the L1 stable orbital point
between us and the Sun, to slightly diffuse its light and cool us down
enough to balance the warming effect of carbon dioxide, methane etc.
That sounds interesting, but what will it cost? Kuro5shin.org says:
Dr Benford, while doing most of the work himself, has exploited his friends
at NASA to confirm that the engineering is viable, and the results were
astounding: The whole project could be achieved with today's technology at
a cost of $10 billion US dollars up-front, and another ten for maintenance
over the decades of designed lifespan.
In addition to the costs and the present problem of trying to get the world to unite on something there is also the potential problem that it would give polluting companies and countries an excuse to continue or even increase their current levels of pollution. And this is if Benford's plan would even work.