Today, Britain’s Royal Society released a report (pdf ), “Geoengineering the Climate,” which urges the increased study of technologies that could counter global warming while cautioning that the side effects could be substantial and possibly prohibitive. Geoengineering “is no magic bullet,” says John Shepherd of the University of Southampton, who chaired the working group, so “we have to keep the focus on [greenhouse gas] emission reductions.”
The new report is probably the most substantial and authoritative since Nobel Prize winner Paul Crutzen made at least the discussion of climate geoengineering respectable again (Science, 20 October 2006, p. 401 ). A 12-member working group of scientists, engineers, an economist, a social scientist, and a lawyer spent nearly a year examining technologies, such as fertilizing the oceans to suck down atmospheric carbon dioxide or orbiting giant mirrors to deflect sunlight.
Responding to many scientists’ concerns, the report stresses that the many impacts of global warming won't be solved by any single technology. Some approaches that would cool the atmosphere, for example, would still allow the continued acidification of the oceans. Right now, pumping up the haze in the stratosphere to block some sunlight looks the most feasible, the working group concluded, but this approach still has serious and inevitable drawbacks such as worsening drought. In addition, none of the proposed technologies yet comes close to measuring up in terms of effectiveness, affordability, and readiness.
Geoengineering may still not look that attractive, but “we should be undertaking research on these technologies so they could be available if and when we need them,” says Shepherd, an Earth systems scientist. That could be late in this century if efforts to rein in emissions falter, he says, or climate proves far more sensitive to greenhouse gases than expected. “We need to initiate serious research not only on the effectiveness of technologies but especially on environmental impacts and legal and ethical ramifications.”
“It’s a pretty good report,” says Princeton University geoscientist Michael Oppenheimer. “It’s definitely constructive,” he adds, but he emphasizes the uncertainties even more than the report does. The report’s recommended further research will, he predicts, make it clear that the risk of geoengineering is too high, no matter how fierce the greenhouse turns out to be.