On February 10, the National Academy of Sciences (NAS) released two major new reports on climate engineering (or “geoengineering”). The reports set out to summarize the scientific basis for what the authors chose to call “climate intervention,” identify governance and ethical challenges, and chart a new research agenda. While the authors were careful to state that climate intervention is no substitute for reduction in carbon dioxide emissions, the reports indicate support for further investigation into large-scale technological responses.

The paired studies assess two specific groups of strategies: (1) carbon dioxide removal and (2) reflecting sunlight, or albedo modification. While the first group of options could, if perfected, reduce the radiative forcing caused by greenhouse gases in the atmosphere, it is unclear if new technologies are ready for large-scale deployment. Similarly, reflecting sunlight could rapidly cool the planet, but such an approach also poses numerous environmental and social risks that are not well understood.

In the wake of the NAS reports, climate engineering remains a controversial proposition. Proponents of climate engineering research and potential deployment suggest that there may be cost-effective ways to remove carbon from the atmosphere and hold it in long-term storage, or ways to reduce incoming solar radiation to curb atmospheric warming. Critics question who will control the new technology and if it will provide an excuse for policymakers to avoid unpopular measures that reduce carbon emissions. There are also possibilities of catastrophic failure of imagined technological systems and the emergence of new international security risks from the development of climate engineering capabilities.

As the NAS report suggests, climate engineering has the potential to reduce some of the impacts associated with carbon emissions; however, it also poses significant risks and uncertainty.