Toward a Responsible Solar Geoengineering Research Program

A combination of greenhouse-gas emission cuts and solar geoengineering could keep temperatures under the 1.5-degree aspirational target of the recent Paris Agreement. It could make the world cooler at the century’s end than it is today. Emissions cuts alone cannot achieve either objective with high confidence. The climate’s inertia along with uncertain feedbacks such as loss of permafrost carbon mean there is a small but significant chance that the world will continue to warm for more than a century after emissions stop.