Tropical Small-Scale Nuclear War Fire Emissions Cause Greater Ozone Depletion Than Extratropical Large-Scale Conflicts

Nuclear conflict can ignite widespread fires that inject massive quantities of smoke particles into the atmosphere. Using the chemistry–climate model CESM2-WACCM6, we simulate idealized nuclear war scenarios with varying emission magnitudes of black carbon (BC) and primary organic matter (POM) released at 150~300 hPa over a 7-day period. Model results show that absorption of solar radiation by BC and POM leads to stratospheric temperature increases exceeding 50 K. This intense heating enhances the vertical lofting of smoke particles, enabling their transport even into the lower mesosphere and significantly extending their atmospheric residence time to over 4 years, thus leading to long-term environmental and climatic impacts. Even a regional nuclear conflict between India and Pakistan, emitting 5 Tg of BC (IP-5B scenario), results in a global total column ozone reduction exceeding 400 Tg (~12%), comparable in magnitude to that simulated for a large-scale nuclear war between USA and Russia with 16 Tg of BC emissions (UR-16B scenario). The co-emission of POM further amplifying stratospheric ozone depletion, leading to increased ultraviolet (UV) radiation at the surface. This heightened UV exposure poses serious risks to ecosystems and human health.