This image, from an article on the Explain That Stuff website about geoengineering, is a derivative work based on NASA’s 1972 (public domain) photo Full Earth, courtesy of NASA Johnson Space Center.

An article in the New Yorker this month explores our (risky) options for ‘geoengineering’ our ways out of climate change. Will such novel approaches be endorsed by the upcoming (June 2012) United Nations Rio+20 sustainable development conference? Will they even be discussed? In light of our glacial speed in agreeing on ways to reduce greenhouse gases, should they be considered a necessary fall-back option?

‘. . . “I know this is all unpleasant,’’ [Hugh Hunt, of Cambridge] said. “Nobody wants it, but nobody wants to put high doses of poisonous chemicals into their body, either. That is what chemotherapy is, though, and for people suffering from cancer those poisons are often their only hope. Every day, tens of thousands of people take them willingly—because they are very sick or dying. This is how I prefer to look at the possibility of engineering the climate. It isn’t a cure for anything. But it could very well turn out to be the least bad option we are going to have.’’. . .

‘“Geoengineering” actually refers to two distinct ideas about how to cool the planet. The first, solar-radiation management, focusses on reducing the impact of the sun. Whether by seeding clouds, spreading giant mirrors in the desert, or injecting sulfates into the stratosphere, most such plans seek to replicate the effects of eruptions like Mt. Pinatubo’s. The other approach is less risky, and involves removing carbon directly from the atmosphere and burying it in vast ocean storage beds or deep inside the earth. But without a significant technological advance such projects will be expensive and may take many years to have any significant effect. . . .

‘The best solution, nearly all scientists agree, would be the simplest: stop burning fossil fuels, which would reduce the amount of carbon we dump into the atmosphere. That fact has been emphasized in virtually every study that addresses the potential effect of climate change on the earth—and there have been many—but none have had a discernible impact on human behavior or government policy. . . .

‘Although the I.P.C.C., along with scores of other scientific bodies, has declared that the warming of the earth is unequivocal, few countries have demonstrated the political will required to act—perhaps least of all the United States, which consumes more energy than any nation other than China, and, last year, more than it ever had before. . . .

‘The planet is getting richer as well as more crowded, and the pressure to produce more energy will become acute long before the end of the century. . . .

‘Recently, Caldeira and colleagues at Carnegie and Stanford set out to examine whether the techniques of solar-radiation management would disrupt the sensitive agricultural balance on which the earth depends. . . .Again, the results were unexpected.

‘Farm productivity, on average, went up. The models suggested that precipitation would increase in the northern and middle latitudes, and crop yields would grow. In the tropics, though, the results were significantly different. There heat stress would increase, and yields would decline.

Climate change is not so much a reduction in productivity as a redistribution,’’ Caldeira said. “And it is one in which the poorest people on earth get hit the hardest and the rich world benefits”—a phenomenon, he added, that is not new. . . .

‘Solar-radiation management, which most reports have agreed is technologically feasible, would provide, at best, a temporary solution to rapid warming—a treatment but not a cure. There are only two ways to genuinely solve the problem: by drastically reducing emissions or by removing the CO2 from the atmosphere. . . .

‘Over the past three years, a series of increasingly urgent reports—from the Royal Society, in the U.K., the Washington-based Bipartisan Policy Center, and the Government Accountability Office, among other places—have practically begged decision-makers to begin planning for a world in which geoengineering might be their only recourse. As one recent study from the Wilson International Center for Scholars concluded, “At the very least, we need to learn what approaches to avoid even if desperate.”. . .

‘Unfortunately, the least risky approach politically is also the most dangerous: do nothing until the world is faced with a cataclysm and then slip into a frenzied crisis mode. The political implications of any such action would be impossible to overstate. What would happen, for example, if one country decided to embark on such a program without the agreement of other countries? Or if industrialized nations agreed to inject sulfur particles into the stratosphere and accidentally set off a climate emergency that caused drought in China, India, or Africa? . . . . What happens then? Where do we go to discuss that? We have no mechanism to settle that dispute.”. . .’

Read the whole article in the New Yorker: The climate fixers, 14 May 2012.