From time to time, the issue of global warming hits the headlines. Scaremongers warn us of a hellish planet in the 21st century, with the polar icecaps melted, sea levels risen by several meters, coastal cities destroyed, and land turned into desert or devastated by out-of-control weather. The other camp dismisses all this as rubbish, and praises industrial pollution as the only thing that stands between us and a new ice age. Some propose entirely novel scenarios, such as a warming-induced shift in the path of the Gulf Stream, resulting in a shift in Europe towards arctic weather patterns.

One thing that is common in all predictions, however, is the underlying assumption that we are but helpless victims of nature's powerful forces and our own nearsightedness. Nothing could be further from the truth.

In reality, even if the worst predictions of the scaremongers come true, global warming remains but a cute engineering problem. Warming is induced by the increased ability of our atmosphere to retain heat, due to a change in the amount of greenhouse gases, such as CO2? Fine... then how about reducing the amount of solar radiation that hits the Earth?

Suppose we wish to reduce the amount of sunshine by ten percent. One way to accomplish this is by placing a mirror between the Earth and the Sun that blocks ten percent of the Sun's disk. Of course this is easier said than done; because the mirror will follow a path prescribed by celestial mechanics, it is not going to stay put. However, it is possible to place a mirror in a relatively stable spot, at the Lagrange point between the Sun and the Earth. A simple, back-of-the-envelope calculation shows that a circular mirror at this distance would have to have a diameter of approximately 5,000 kilometers to block the desired percentage of the Sun's disk.

Now making a 5,000 kilometer mirror isn't exactly an easy task; the largest space mirror to date, to the best of my knowledge, measures only about 30 meters across. But it is not impossible. Using ultra-lightweight materials with a density of 10 kilograms per square kilometer, the total weight of the mirror would come to roughly 200,000 metric tons. This is a hell of a lot of weight; and if we add structural materials, station-keeping systems, and such, we're probably into a million tons or more. Still... building mechanical structures of this size is not unprecedented. There are large oil tankers on the Earth's oceans today that weigh more when fully loaded.

Of course putting all this mass into orbit is a different issue altogether. Present-day space transportation systems can lift at most about 100 metric tons to Low Earth Orbit (LOE). The mass that can be moved to the Lagrange point is considerably less. At this rate, we would literally require tens of thousands of launches in order to lift all the needed material for our space mirror.

But who said that we must be restricted to using Apollo-era chemical rockets? After all, if the planet's survival is at stake, then perhaps even die-hard opponents of nuclear propulsion can be convinced to suspend their tendency to panic at the first uttering of the word 'atom' just this once. Advanced nuclear propulsion systems can presumably be developed and be made to deliver much larger payloads into orbit using reusable vehicles.

We also do not need to assemble all our space mirror components on the Earth. It is entirely reasonable to believe that a lot of the mass can be obtained from sources in space, such as asteroids. It is conceivable that obtaining materials this way will be better than lifting them from the Earth's surface, despite the considerably energy requirements of space mining, manufacturing, and moving the resulting components to the correct orbit.

But the bottom line is this: global warming is not an unstoppable evil, it is simply an engineering problem. Be it far from me to advocate pollution or other forms of irresponsible abuse of nature; however, I am of the firm belief that the real problem is not that but our newly acquired inability to dream. A generation ago engineers built spacecraft that took people to the Moon, and proposed serious designs for vehicles that would take our instruments all the way to the stars. Today, we cower in fear, denounce those who still dream of the future made possible by our science, and ban the most progressive areas of research in the name of public safety. Perhaps we do deserve to suffocate in the heat of our nearsightedness and small-mindedness.