05/31/2008 02:55 am ET Updated May 25, 2011

Slouching towards geo-engineering?

Few debates have so riven the scientific community in recent years as the one over geo-engineering -- the deliberate application of technologies to directly modify the global climate. What once began as more of an academic exercise between scientists arguing over the validity of potential mitigation strategies such as ocean fertilization and sulfate aerosol injection has, over the past year, spilled into the public realm -- with names like Paul Crutzen and Climos now regularly grabbing headlines. Indeed, no less than The New York Times and Newsweek, among other major news publications, have accorded the controversial topic prominent real estate in recent months.

While scientists continue to come up with ever more creative and elaborate schemes, the ones we have now become most familiar with are: ocean iron fertilization (OIF), the idea that dumping iron into the oceans could stimulate large-scale phytoplankton blooms which, in turn, would result in the drawdown of atmospheric carbon dioxide; carbon capture and storage (CCS), in which carbon dioxide from coal plants is pumped, or sequestered, underground into geological wells; genetically-engineered "super" trees that could take up larger amounts of carbon dioxide; and reflecting incoming solar radiation by injecting sulfate aerosols into the stratosphere. Supporters of these schemes argue -- with some merit -- that we can no longer afford to wait for strategies like cap-and-trade or renewable energy to resolve the climate crisis; given the slow progress made in getting the world community to even commit to modest emission cuts (not to mention the increasingly pessimistic GHG emissions growth scenarios) we shouldn't be taking any potential remedies off the table just yet -- even ones fraught with such risk.

To be clear, even its most vocal advocates oppose the immediate, large-scale implementation of geo-engineering schemes -- particularly those attached to commercial entities, such as the ill-fated Planktos, seeking to sell carbon offsets. In an article published earlier this year in Science, an international group of scientists unequivocably stated that commercial-scale OIF operations should not take place until there is clear evidence to support its use. Furthermore, they say, such a scheme "should only be done if society is willing to acknowledge explicitly that it will result in alteration of ocean ecosystems and that some of the consequences may be unforeseen." Similar statements have been trotted out by scientists who advocate the use of sulfate aerosol injection and other geo-engineering schemes.

The common strand of thought that has unified scientists who oppose geo-engineering was best summed up by Rutgers University's Alan Robock, writing in the latest issue of The Bulletin of the Atomic Scientists: "But is this cure worse than the disease?" Robock goes on to lay out the 20 reasons why he believes geo-engineering is a bad idea, citing a range of ethical, biological and political issues. The central argument of his piece is premised on his belief that solving global warming is primarily a political issue: Replace the disastrous government policies that have gotten us into this mess with a progressive mix of emission reductions policies and renewable energy mandates and, voila! There won't be a need for geo-engineering.

You'd be hard-pressed to find many scientists who don't believe that an aggressive climate policy could solve many of our global warming woes. The problem, of course, boils down to a question of political will: Will the next president -- and, to a broader extent, the American public -- be willing to make the necessary (and painful) lifestyle changes to adapt to our warming climate? While there are certainly ways to help ease this transition -- by fostering the creation of a green-collar industry and by incentivizing the adoption of eco-friendly technologies, for example -- many remain unconvinced that we'll be able to meet these challenges in time.

In another article published in The Bulletin of the Atomic Scientists, several geo-engineering advocates, including Climos founder Dan Whaley, make the case that we should give these schemes a chance -- even if it's only studying their efficacy as potential mitigation tactics. Indeed, they point out that Robock himself has suggested that we should further investigate their effectiveness and possible side effects. Ken Caldeira of Stanford University's Carnegie Institution, who concedes that geoengineering may not be a "panacea," quips that: "Climate engineering may indeed be a bad idea, but so far, better ideas to mitigate global warming show little traction."

That may be so -- but a number of recent studies has demonstrated that the costs of geo-engineering could far outweigh the perceived benefits. For instance, a new Science study found that injecting sulfate aerosols into the atmosphere could severely damage the ozone layer. Another study, published in Geophysical Research Letters, showed that reflecting incoming solar radiation (through the use of a large "sunshade") would impact the hydrological cycle, leading to a drier global climate.

While it may yet be too early to close the door completely on geoengineering, it's clear that much more research will be needed before we can even begin to seriously consider its use.