Fact or Fiction?: Geoengineering Can Solve Global Warming
A global deal to combat climate change lurches toward reality in Lima, Peru, this week—and yet any politically feasible agreement will be insufficient to restrain continued warming of global average temperatures, perhaps uncomfortably high. Although recent pledges by China, the 28 countries of the European Union and the U.S. are the first signs of the possibility of restraining the endless growth of greenhouse gas pollution on a long-term basis, atmospheric concentrations of carbon dioxide have crossed the threshold of 400 parts per million—and will reach 450 ppm in less than two decades at present growth rates. The estimated one trillion metric tons of carbon the atmosphere can absorb could be burned through in even less time, particularly if India, as it develops, picks up where China leaves off by burning coal without any attempt to capture the CO2 before the greenhouse gas spews from smokestacks.
Geoengineering could play a role in coping with some of the impacts of climate change, perhaps used to cool off the rapidly warming Arctic and save summertime sea ice. Or "these strategies might be used throughout the period required to replace fossil fuel burning with globally distributed clean energy and even be continued while CO2 concentrations remain too high," as atmospheric scientists put it in an overview of the Philosophical Transactions issue. Small-scale tests of such techniques are therefore warranted to assess the real risks, such as unexpected chemical reactions with the existing mix of atmospheric gases, for example. Of course, it took massive emissions of CO2 to detect human-caused global warming, suggesting small-scale tests may not reveal much. And even at a miniscule scale engineering the climate remains a radical step with consequences for both the climate and civilization that cannot be predicted in advance.
There is no technological fix for global warming other than the hard work of transforming a global energy system that relies on burning fossil fuels into one that relies on energy sources—the sun, Earth's heat, fission or, maybe some decade, fusion—that do not use the atmosphere as a dump. The fact that geoengineering cannot suffice is good news because it means that a viable form of climate engineering cannot undercut the urgency of making that switch. No form of climate engineering can solve global warming at present. To think so is science fiction.
scientificamerican