Exploring the Possible Risks, Benefits of Geoengineering

Sesno kicked off the conversation by asking Field and McNutt to share their own definitions of solar geoengineering.

“Solar geoengineering is a grab bag term for any of a number of techniques to moderate how much sunlight reaches Earth’s surface to warm the planet,” said McNutt. But currently, our scientific understanding of solar geoengineering is limited. “We don’t even know if solar geoengineering is better than other options, and better for whom [and] in what way.”

“Not a Comprehensive Solution”
There are many unknowns about the consequences of solar geoengineering and its effectiveness, and both panelists emphasized that the strategy is an unexplored option, and one that could only be considered after far more robust, extensive research.

Field and McNutt cited concerns about the possibility of detrimental physical and social consequences from solar geoengineering, including intensification of drought, threats to national security, and challenges related to issues of environmental justice and equity.

“Solar geoengineering is not a comprehensive solution,” said Field. He stressed that there are many aspects of climate change that the approach does not address, including ocean acidification. The effects of solar geoengineering on weather patterns and stratospheric ozone have not been adequately explored, he said. “Those are important enough that we wouldn’t even be close to arguing for deployment until we learn a lot more.”

“Once you already get to the point where it’s too difficult to adapt, and you haven’t mitigated, and the situation is so bad, what can you do to try to lessen how bad it is, by some sort of band aid?” One possible band aid is solar geoengineering, McNutt said.

The Need for More Research
McNutt and Field underscored the importance of doing much more research before any decisions are made.

“There’s been some modeling done, but models are only as good as the data that are [entered] into them,” McNutt said. “This is another reason why we need to do research to understand those impacts.”

Exploring the technical feasibility of solar geoengineering is a complicated process, made more challenging by public concerns about the approach, as the 2021 report notes.

“The social feasibility is, if anything, even more complicated than the technical feasibility, and it needs to be researched,” Field said. Early experiments proposed in recent years have been met with public resistance, which must be addressed for research in solar geoengineering to move forward. “Otherwise, it’s very likely that the agenda wouldn’t be able to move forward, even if it was technically a good idea,” Field said.

“I think when it comes to going beyond research, as Chris has said, this has to involve civil society; it cannot be a discussion [only] among scientists,” McNutt added.

Exploring a Last-Ditch Option
The 2021 report recommends a national solar geoengineering research program, strong cooperation with other nations, robust research governance, and meaningful public engagement.

“There really are profound questions that have not yet been answered about what kind of governance structures could be effective,” Field said. “That’s part of the research agenda — to test-drive concepts about what might work and what might not.”