Critics of geoengineering point out that speculation about future technologies is just another form of greenwashing and denial, and that the same engineering industrial complex that profits off our addiction to fossil fuels is likely to profit from our quest to geoengineer the planet. Further, they argue that we don't have much more than a rudimentary understanding of what the broader consequences of these technologies might be, especially the ones that change the reflectivity of the planet. How would injecting particles into the stratosphere affect rainfall in the Amazon? Would it shift the monsoons, threatening the food supply for millions of people? Then there are questions about governance, fairness, and morality. If we decided to modify the climate, whose hand would be on the proverbial thermostat? And if something went wrong, who would eat the risk?
Despite all these uncertainties, there are good reasons not to write geoengineering off too quickly. For one thing, we're already manipulating the climate in a big way by dumping nearly 9 billion tons of carbon into the atmosphere each year. * So it's hard to argue that geoengineering is the atmospheric equivalent of building a strip mall in an old-growth redwood forest. As for ethical concerns, it's true that any full-blown geoengineering scheme is likely to be designed and implemented by rich and powerful nations (or individuals, for that matter). It's not hard to imagine these schemes being used in self-interested ways—nothing topples regimes like a good famine. But it's also possible to imagine how these schemes might serve more communitarian impulses. Forget conventional climate change: If it were within our technical capability to bring more rainfall to the Sahel and thus boost food production in one of the most desperate regions of Africa, wouldn't we at least have an obligation to explore that idea?
More broadly, cooling off the planet quickly is something we might actually need to do. Despite 30 years of scientific research and public discussion about the dangers of dumping greenhouse gases into the atmosphere, we're making zero progress at reducing emissions. Meanwhile, the planet continues to heat up: 2010 is likely to turn out to be the hottest year on record, with killer heat waves in Russia and near-record melting in the arctic. Due to the peculiarities of the climate system, even if we stopped burning fossil fuels tomorrow, the planet would continue to warm for decades. If we needed to cool the planet off in a hurry—say, to slow the rapid melt of the Greenland ice sheets—geoengineering might be one of our only options.
Then there's politics. You can wring your hands all you want about the dangers of quick fixes, but they are an easy sell. In the not-too-distant future, geoengineering will undoubtedly be packaged by Big Coal as a diet pill for our climate and energy problems, a cheap and easy way to avoid the difficult task of weaning ourselves off fossil fuels. If that happens, it would be a disaster, because geoengineering is in no way a substitute for cutting emissions. But if we pursue the development of these emergency measures with care and intelligence, they might turn out to be useful tools for lessening the impacts of climate change and buying time to reinvent our energy infrastructure.
But the best argument for taking geoengineering seriously is that it changes how we frame the problem. You cannot have a thoughtful debate about geoengineering without confronting the question: What kind of climate do we want? And what price—in economic, environmental, and human terms—are we willing to pay to get it? These questions are already implicit in conversations we have today about emissions targets and energy policy, but with geoengineering, they are suddenly explicit. They make clear the fundamental fact of our predicament today—that we are, at this very moment, designing the future of the planet. We are in charge. We might choose to do nothing, or we might choose to stop burning fossil fuels in the next decade, but it is our decision either way, and one that will have tremendous consequences not just for our children and grandchildren, but for all life on Earth.
Geoengineering may or may not turn out to a valuable tool to reduce the risks of climate change. But if exploring it helps us to better understand what's at stake in our rapidly warming world, then it's worth pursuing. Because in the end, the greatest danger we face is not technological hubris. It's human apathy.
Correction, Sept. 27, 2010: This sentence originally referred to 9 billion tons of CO2. (Return to the corrected sentence.)