Should solar geoengineering be part of how humanity counters climate change?

[Geoeng Info]

https://physicstoday.scitation.org/doi/10.1063/PT.3.4768

Should solar geoengineering be part of how humanity counters climate change?

Moving forward requires research and international and intergenerational participation.
Toni Feder

Solar geoengineering research should be cautiously ramped up, says the US National Academies of Sciences, Engineering, and Medicine (NASEM) in a report released on 25 March. Tools to cool the planet cannot undo global warming, but they may avert some of its worst impacts.

Today’s average global temperature is 1.2 °C higher than preindustrial levels, and last year was among the three hottest on record, according to the World Meteorological Organization. The 2015 Paris Agreement’s long-term goal is to keep the rise well below 2 °C and to try to limit it to 1.5 °C. But models predict that unless extraordinary measures are taken, the increase could reach or even exceed 4 °C by the end of the century.

“We are in a critical time for tackling climate change,” says Chris Field, an environmental scientist at Stanford University who chaired the NASEM committee. “We know it’s difficult to make societal changes to get to zero greenhouse gas emissions. That difficulty provides a compelling motivation to understand the full portfolio of options.” Solar geoengineering may be a useful addition to the existing options of reducing emissions, removing carbon from the atmosphere, and adapting to warming. (See, for example, the article “Negative carbon dioxide emissions,” by David Kramer, Physics Today, January 2020, page 44.)

The report, Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance, urges that research be pursued in the intertwined areas of science, technical feasibility, impacts, risks, and benefits. Ethics, public perceptions, and governance of climate interventions also need to be considered. It recommends that the US government invest $100 million–$200 million over five years. Such a funding level would represent a multifold increase over current global spending on climate intervention but would be a small fraction of the overall funding for climate studies.

The report emphasizes inclusivity; the whole world should be involved in decisions that have universal impact. And while it endorses research, it also stresses that neither NASEM nor the report’s authors advocate the deployment of solar radiation modification. Research into solar geoengineering “is a threat-reduction study,” says Paul Wennberg, an atmospheric chemist at Caltech and a member of the NASEM committee. “It’s shocking that we are thinking about doing this kind of stuff. It shows we are globally in a pickle. It highlights how critical it is to quickly reduce our greenhouse gas emissions.”