They War-Gamed Dimming the Sun. It Went Worse Than You Think

A first-of-its-kind diplomatic simulation tested how governments, scientists, companies, and advocacy groups might respond to solar radiation modification: releasing reflective particles into the atmosphere to cool Earth. The technique could temporarily counter warming, much as volcanic eruptions do, but its regional effects are uncertain and potentially harmful, and temperatures could rebound sharply if deployment stopped. With private companies pursuing the technology and some political figures backing it, participants were asked to negotiate international rules as fictional research and deployment developments raised the stakes.

The exercise instead exposed how strategic rivalry could overwhelm science and cooperation. US and Chinese players resisted limits that might benefit the other, and misleading intelligence reports fueled accusations; talks collapsed although China was not secretly experimenting in the scenario. Participants largely ignored climate-impact advice until a reported aerosol plume made monitoring urgent. Then a fossil-fuel-backed group offered funding for surveillance, undermining the credibility of the scientific adviser it approached. No agreement emerged: proposals for safeguards and open research were stalled by distrust, delay, and competing interests. The simulation suggests that fear of falling behind could spur research and suspicion of rivals, even without a decision to deploy. It also highlights how commercial and fossil-fuel interests, weak scientific understanding, and the absence of trusted international oversight could turn a potential climate intervention into a source of geopolitical conflict.