GEOENGINEERING: Global temperature fell by half a degree when just one volcano—Mount Pinatubo—erupted in 1991 and produced large amounts of light-reflecting sulfates, which act like a mirror over Earth, reflecting radiation away from the surface. Image: Flickr/NASA Goddard Photo and Video
Cutting greenhouse gas emissions, redefining floodplains and building sea walls may not be enough to protect against the most devastating climate change impacts like fires, floods, heat waves and drought. As a result, some are pushing scientists to explore every possible option to keep the world from getting warmer, including geoengineering.
This idea encompasses strategies to reflect sunlight back into space by seeding clouds or spraying aerosols into the air, as well as soaking up greenhouse gases directly from the atmosphere with giant machines or microorganisms. In an article published last week in the journal Science, two researchers argue that governments need to step into geoengineering research, coordinating internationally to lay down the law on this scientific frontier before someone takes these experiments into his or her own hands again.
Last July, California businessman Russ George dumped 100 metric tons of powdered iron off Canada's Pacific Coast in an attempt to spawn carbon dioxide-sucking plankton, thereby generating carbon credits to aid an ailing fishing community (Greenwire, Oct. 17, 2012).
Though American and Canadian governments were aghast, what George did wasn't barred by any international regulations, explained Harvard University professor David Keith, who co-authored the article and holds joint appointments in the school's public policy and physics departments. On the other hand, there is no federal support for geoengineering experiments in the United States and minimal support globally, deliberately hampering a potential climate lifeline and making renegade research the most attractive option, he noted.
"The central thing that's lacking is enough agreement in how to govern this thing to give people the freedom to go forward in [geoengineering] research," Keith said.
Getting wary public officials on board may be challenging. White House science adviser John Holdren gingerly supported geoengineering research in the past. "I said that the approaches [to geoengineering] that have been surfaced so far seem problematic in terms of both efficacy and side effects, but we have to look at the possibilities and understand them because if we get desperate enough it will be considered," Holdren wrote in an email to reporters and scientists in 2009.
Other researchers and scientists expressed concern about potentially irreversible environmental damages, since tiny amounts of aerosols can have significant global effects. There are also worries that once you open the door to small-scale projects, you're only a few steps away from reckless scientists filling the sky with sulfur-seeded clouds. This slippery slope argument has made geoengineering a bête noire for researchers and funding agencies, even though simulations suggest these approaches could slow, stop and even reverse climate change.
Keith said the environmental risks are exaggerated but proposed a moratorium on large-scale geoengineering projects. In this case, large-scale means experiments that would change the amount of energy the Earth absorbs from the sun by more than 0.01 watt per square meter annually. This is the threshold where instruments barely start detecting changes in the planet's solar reflection and absorption.
Setting a global framework for small experiments
However, governments should facilitate experiments that change atmospheric energy uptake by less than a microwatt per square meter per year. This proposal conspicuously and deliberately leaves a wide gulf between the moratorium and the experimental threshold to give policymakers flexibility while allowing the most promising and urgent research to proceed.
"You could learn a huge amount that is useful from very small experiments," Keith said. An example of experiment at this scale would be releasing 1 ton of water vapor into the atmosphere, which is less than the vapor produced by one trans-Atlantic flight.