Targeting Solar Geoengineering to Combat Global Warming

A new study published in the November issue of Nature Climate Change suggests that solar geoengineering can be tailored to reduce inequality or to manage specific risks like the loss of Arctic sea ice.

Solar geoengineering, the goal of which is to offset the global warming caused by greenhouse gases, involves reflecting sunlight back into space. By increasing the concentrations of aerosols in the stratosphere or by creating low-altitude marine clouds, the as-yet hypothetical solar geoengineering projects would scatter incoming solar heat away from the Earth’s surface.

Geoengineering of all types has been a subject of much debate, with critics arguing that such a global intervention would have unequal effects around the world and could result in unforeseen consequences.

However David Keith, a professor of Applied Physics at the Harvard School of Engineering and Applied Sciences (SEAS) and Professor of Public Policy at the Harvard Kennedy School , argues that this new study highlights the possibility of controlled geoengineering that minimizes unpredictable results.

Generally speaking, greenhouse gases tend to suppress precipitation, and an offsetting reduction in the amount of sunlight absorbed by Earth would not restore this precipitation. Both greenhouse gases and aerosols affect the distribution of heat and rain on this planet, but they change the temperature and precipitation in different ways in different places. The researchers suggest that varying the amount of sunlight deflected away from Earth both regionally and seasonally could combat some of this problem.

“While more work needs to be done, we have a strong model that indicates that solar geoengineering might be used in a far more nuanced manner than the uniform one-size-fits-all implementation that is often assumed. One might say that one need not think of it as a single global thermostat,” Keith reported in a Harvard University press release. He continued, “This gives us hope that if we ever do need to implement engineered solutions to combat global warming, that we would do so with a bit more confidence and a great ability to test it and control it.”


Courtesy of Harvard School of Engineering and Applied Sciences

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