Geoengineering might sound crazy, but it's worth talking about.

What's to come?
Sept. 23 2010 11:00 AM

Let's Talk About Geoengineering

It might sound crazy, but it's a conversation worth having.

Future Tense: ASU | NEW AMERICA | SLATE

This piece arises from Future Tense, a collaboration among Arizona State University, the New America Foundation, and Slate. A Future Tense conference on geoengineering will be held at the New America Foundation on Monday, Sept. 27. (For more information, please visit the   NAF Web site.) Read more of   Slate's special issue on geoengineering.

It doesn't take much imagination to dismiss geoengineering as a sci-fi fantasy writ large. The whole notion of geoengineering—which the British Royal Society defines as "the deliberate large-scale intervention in the Earth's climate system, in order to moderate global warming"—reeks of human hubris and technocratic arrogance. Just talking about it seems, at best, a distraction from the urgent business at hand, which is developing the political will to reduce greenhouse gas pollution. After all, if global warming might be a problem that could be fixed by tossing sulfur particles into the stratosphere to reflect away sunlight, hell, why bother cutting back on fossil fuels? Jump in the SUV and party on.

The only thing more reckless than embracing geoengineering, however, would be to dismiss it. Yes, it's a dangerous, crazy idea. In a rational world, we would never consider it. But we don't live in a rational world. (If we did, subsidies for the fossil fuel industry wouldn't be 12 times greater than subsidies for renewable energy.) We live in a world that likes quick fixes and easy answers, and in that world, geoengineering has a lot of political and economic appeal. The real question is: Will we pursue it in an intelligent way that helps us manage the risks of global warming and deepens our understanding of how the climate system works, or will it simply turn into, as one blogger put it, "a ramifying suite of mega-engineering wet dreams" that leads to a whole new dimension of chaos?

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Geoengineering typically refers to two different approaches to cooling the planet. The first includes all those technologies that would change the reflectivity, or albedo, of the earth. If we could reduce the amount of sunlight that hits the surface of the earth by about 1 percent, that would be enough to offset the warming that comes from a doubling of atmospheric CO2 levels (a common benchmark used by climate scientists). One way to do this would be to mimic a volcano and throw a small amount of dust high into the stratosphere; the particles act as tiny mirrors, scattering sunlight. Other approaches include brightening clouds over the oceans so that they reflect more light, or merely painting our roads and rooftops white.

Mount Pinatubo. Click image to expand.
The Mount Pinatubo volcano erupts

Scientists believe that these ideas would work because there are real-world analogies: Big volcanic eruptions, such as Mt. Pinatubo in 1992, lowered the temperature of the earth by half a degree or so for nearly a year; the exhaust from diesel ship engines, which contains tiny particles of soot, generate clouds in certain conditions. Of course, reducing the temperature of the Earth by reflecting sunlight does nothing to solve the other problems caused by high CO 2 levels, the most urgent of which may be ocean acidification. But in comparison to the cost of rebuilding our energy infrastructure, it's quick and cheap.

The second approach to geoengineering is to develop new technologies for pulling CO2 out of the atmosphere. One method would be to stimulate plankton blooms in the oceans, which in turn would absorb carbon. Another idea is to build CO2-sucking machines that function like artificial trees. A handful of scientists have built working prototypes of these machines, but they are still crude, inefficient, and wildly expensive. Still, it's not impossible to imagine that someday we could build what amounts to an iron lung for the planet.