A cheap and easy plan to stop global warming

February 8, 2013

Phytoplankton bloom as a form of geoengineering (credit: Wikimedia Media)

Here is the plan. Customize several Gulfstream business jets with military engines and with equipment to produce and disperse fine droplets of sulfuric acid. Fly the jets up around 20 kilometers-significantly higher than the cruising altitude for a commercial jetliner but still well within their range. At that altitude in the tropics, the aircraft are in the lower stratosphere, reports MIT Technology Review.

The planes spray the sulfuric acid, carefully controlling the rate of its release. The sulfur combines with water vapor to form sulfate aerosols, fine particles less than a micrometer in diameter. These get swept upward by natural wind patterns and are dispersed over the globe, including the poles.

Once spread across the stratosphere, the aerosols will reflect about 1 percent of the sunlight hitting Earth back into space. Increasing what scientists call the planet’s albedo, or reflective power, will partially offset the warming effects caused by rising levels of greenhouse gases.

The author of this so-called geoengineering scheme, David Keith, doesn’t want to implement it anytime soon, if ever. Much more research is needed to determine whether injecting sulfur into the stratosphere would have dangerous consequences such as disrupting precipitation patterns or further eating away the ozone layer that protects us from damaging ultraviolet radiation.

Even thornier, in some ways, are the ethical and governance issues that surround geoengineering — questions about who should be allowed to do what and when. Still, Keith, a professor of applied physics at Harvard University and a leading expert on energy technology, has done enough analysis to suspect it could be a cheap and easy way to head off some of the worst effects of climate change.

According to Keith’s calculations, if operations were begun in 2020, it would take 25,000 metric tons of sulfuric acid to cut global warming in half after one year. …

Once under way, the injection of sulfuric acid would proceed continuously. By 2040, 11 or so jets delivering roughly 250,000 metric tons of it each year, at an annual cost of $700 million, would be required to compensate for the increased warming caused by rising levels of carbon dioxide. By 2070, he estimates, the program would need to be injecting a bit more than a million tons per year using a fleet of a hundred aircraft.

One of the startling things about Keith’s proposal is just how little sulfur would be required. A few grams of it in the stratosphere will offset the warming caused by a ton of carbon dioxide, according to his estimate. …