Simulated Response of Extreme Moisture Transport to Nuclear Conflict

Abstract Nuclear war has the potential to cause global catastrophe, as soot from widespread fires blocks sunlight, triggers abrupt cooling, and collapses agriculture. This study examines the long‐term response of weather and climate patterns to nuclear conflict, simulated by injecting ∼150 million tons of smoke into the stratosphere within the Community Earth System Model. An algorithm detecting extreme moisture transport events is applied to evaluate global hydrological impacts. The simulations reveal widespread declines in event frequency, particularly during each hemisphere's summer, but also narrow ocean‐to‐continent corridors of sharp frequency increases during the cold season, including across the North Pacific to the U.S. West Coast, the eastern North Atlantic to North Africa and extending eastward toward South and Southeast Asia, the South Pacific to Chile, and the South Indian Ocean to Australia. In these regions, extreme moisture transport events make disproportionately large contributions to total precipitation. Changes in event distribution are largely driven by circulation changes following the smoke injection: subtropical jets contract equatorward, continental surface anticyclones intensify, and anomalously strengthened offshore cyclones establish anomalous coastal pressure gradients, favoring enhanced moisture transport toward coastal locations. Over southwest North America, these events feature a classic atmospheric river (AR)‐like pattern during all seasons following the smoke injection, which contrasts with the control simulation where AR‐like characteristics appear only during the cold season. This study offers novel insight into how nuclear conflict could profoundly disrupt the global hydrological cycle and extreme precipitation, with critical implications for regional water resources in a severely perturbed climate system.