This week, the Office of Sustainability & Environmental Studies hosted an international panel on the science, policy and politics of climate geoengineering. The event, which was held on Jan. 31 from 2:30 to 4 p.m. in Rapaporte Treasure Hall, featured speakers from Tufts University and Wageningen University in the Netherlands, with Prakash Kashwan, Associate Professor of Environmental Studies and Affiliated Faculty at the Heller School, moderating.

Bill Moomaw, Professor of International Environmental Policy at Tufts University, presented first on some of the downsides of climate geoengineering. One of the most commonly discussed types of climate geoengineering is known as solar radiation management, also called “solar climate intervention.” This entails injecting certain types of molecules, such as sulfuric acid, into the atmosphere to reflect some of the sun’s radiation back out into space. This practice is heralded by some, including David Keith as Moomaw mentioned, as a way “to slow climate change without making any region worse off.”

Moomaw explained that in addition to the high levels of risk that come with implementing solar radiation management, one of the potential drawbacks of this method could be a reduction in the productivity of green plants that must photosynthesize with lower amounts of sunlight. Moomaw also mentioned the potential negative effects on the recovery of the ozone layer, which itself is still healing from our use of chlorofluorocarbons, or CFCs, which come from air conditioning and refrigeration technologies.

Another type of climate geoengineering Moomaw described is carbon dioxide removal, or CDR. This technique can involve technological methods which extract CO2 from the atmosphere and then convert it to fuel or store it in the ground, according to Moowmaw. However, these methods are costly: in order to remove 10 gigatons of CO2 from the atmosphere—we emit 40 gigatons a year—at a rate of $200 a ton, it would cost more than the U.S. military budget, according to Moomaw. Current estimates of the cost of CDR vary, Moomaw explained, but it can cost closer to $1000 to remove each ton of carbon. 

Moomaw also covered natural methods of CDR, which are performed by forests, oceans and marine plants. He left the audience with the question: are we to change the earth to fit our economies and technologies, or change our society to fit the earth?

Next up was Kashwan, filling in for planned speaker Wil Burns, who was unable to attend. Kashwan discussed some of the social and equity concerns of CDR, including the question of whose land is to be used to house CDR and carbon storage facilities. Other risks Kashwan described include food insecurity, land grabs, damages to biodiversity, and drawbacks that have to do with the geochemistry of carbon injection into the ground. This method of carbon storage uses similar techniques to hydraulic fracturing, also known as fracking, according to Kashwan, who explained that fracking is known to cause issues including localized earthquakes.

The final speaker was Aarti Gupta, Professor of Global Environmental Governance with the Environmental Policy Group in the Department of Social Sciences at Wageningen University in the Netherlands. Gupta’s presentation explored issues of governance when it comes to a global issue such as climate geoengineering. Some solar geoengineering proponents describe the method as a cheap and quick temporary solution, but Gupta posed the question of who exactly these methods are intended to buy time for. Gupta laid out the case for an international non-use agreement when it comes to solar geoengineering, as it would be extremely difficult to globally govern such a rollout in a just and equitable way. Gupta also pointed out that although a small group of individuals is leading the push for climate geoengineering, they have an outsized influence, and even though the mainstream climate movement is not focusing on geoengineering, “it’s waiting in the wings.”