War game on solar geoengineering exposes risks of cooling the planet

A London simulation in September examined how the world might respond to solar geoengineering, a set of technologies intended to cool Earth by reflecting part of the sunlight reaching the planet.

A couple dozen foreign-policy experts, scientists, military personnel and former government officials from around the world took part at Queen Mary University of London.

Governments and organizations in the simulation

Titled “Exploring Geopolitical Tipping Points and Climate Cooling Strategies,” the exercise assigned participants to represent national governments, climate nonprofits, Indigenous groups and technology companies.

Climate researcher Colleen Golja provided technical advice intended to help participants make scientifically informed decisions. She said she had expected agreement on conducting ethical research, but found the issue far more difficult.

Uneven effects of planetary cooling

Solar radiation modification could involve spraying sulfur dioxide or another manufactured substance into the atmosphere. The approach would imitate the cooling effect of major volcanic eruptions, which can temporarily lower global temperatures by half a degree or more.

The consequences would not be evenly distributed, and remain uncertain. Climate models predict drying in sub-Saharan Africa and more intense tropical storms in the Atlantic.

The cooling would last only while geoengineering continued. If it stopped, global temperatures could rise sharply, producing large and difficult-to-predict effects.