China’s Silver Linings Playbook: Evidence from 27,000 Cloud Seeding Operations

Abstract
While many countries have experimented with cloud seeding to influence precipitation, evidence regarding its effectiveness remains mixed and inconclusive. In this paper, we examine cloud seeding operations in China—arguably the most large-scale and systematic effort for weather modification in recent history. Using detailed information on nearly 27,000 cloud seeding operations conducted since 2014, we document three primary findings. First, our results indicate that cloud seeding effectively alters precipitation in regions with otherwise identical meteorological conditions. Second, we find that the spillover effect of a cloud seeding operation on precipitation in adjacent localities is initially positive during the operation, subsequently turns negative, and eventually converges to zero within one week. Third, our findings provide evidence for several practical applications of cloud seeding in China, including the prevention of undesirable weather conditions for major events, the enhancement of soil moisture, and the mitigation of ambient air pollution.