David Keith: Solar Geoengineering Techonology and Implications for Public Policy

Just days after the National Research Council released a two-volume report concluding "climate intervention" is too risky and should not be used in the near future, EPIC hosted renowned geoengineering scholar David Keith on February 11th. Keith, a professor of Applied Physics and Public Policy at Harvard University, is a proponent of geoengineering and has encouraged further research, including field studies. He believes the world should be ready to use geoengineering as a stopgap measure if all mitigation efforts fail to thwart climate change.

In an interview with NPR after the report’s release, Keith said: "The central, biggest fear is the fear that just even talking about this, or researching it and popularizing it, will lessen the strength of our commitment to cut emissions.”

Keith said the report opens the door to change as it calls for stronger research, including field research.  He has proposed one field experiment that would apply a solar geoengineering technique, the subject of his EPIC talk. With solar geoengineering, also known as solar radiation management, aerosols – such as sulfate particles – would be purposely dispersed into the atmosphere to reflect part of the sun's light rays, and in theory counteract some effects of heat trapping greenhouse gases. As the sun's light is reflected, the Earth's temperature would decline and the rate of global climate change would subsequently decelerate. To test if this approach would work, Keith has proposed to spread a minuscule amount of sulfate particles into the atmosphere to see what effect it has on ozone and whether that effect could be managed.

Although some controversy surrounds solar geoengineering as a tactic to abate the effects of climate change, Keith emphasized three aspects that can make it a potentially viable solution. First, it should be seen as a temporary mitigation mechanism in which the end point is an environment with actually no need for solar geoengineering. Second, the flexibility of dispersing aerosols in the atmosphere at different levels allows the process to be responsive to any unforeseen changes to the environment. Finally, the use of solar geoengineering should be understood as a moderate measure to help reduce the rate climate change, not a catchall solution to counteract the effects of greenhouse gases without reducing the rate of emissions.

"As a disclaimer, [solar geoengineering] is not a process that once you start doing it you have to do it forever," Keith said during the seminar. "It can help reduce the rate of temperature change, which can have larger benefits in the future, but does not need to be used permanently."

Still, concerns remain regarding the potential moral hazard of using solar geoengineering as a substitute to reducing carbon emissions. As Keith explained, because solar geoengineering is not excessively costly, and the technology is readily available to almost all countries, one of the future policy implications is to create a viable monitoring scheme to regulate regional use.

When compared to other forms of climate change mitigation, solar geoengineering still has a comparative leverage in terms of its low initial costs and the ability to 'turn it off and on' in simple terms, Keith said. However, concerns remain regarding researchers' ability to test for all possible side effects or unintended consequences of deflecting the sun's rays on such a large scale before countries begin using this option widely.

UChicago’s Ray Pierrehumbert, a co-author of the report, remains skeptical of even this type of field experiment. He said in a Slate opinion piece that “the new NRC report’s specific research recommendations are actually quite cautious, focusing primarily on things that contribute to a better understanding of climate in general,” such as modeling efforts.

article re-posted from EPIC