Guest seminar, Simchan Yook, Department of Earth, Atmospheric, and Planetary Sciences, MIT, USA
Seminar
Date:Tuesday 22 April 2025
Time:11.15 – 12.15
Location:C609 Rossbysalen, MISU, Svante Arrhenius väg 16C, 6th floor
Title: Nuclear War In a World Brimming With Plastic: Impacts of Cl, Br, and Organics on the Ozone Layer
Abstract
Nuclear wars would cause immediate harm to humanity and ecosystem due to massive explosions, intense heat, and radioactive fallout. In addition to the immediate fatalities, previous studies predict that smoke generated by large-scale fires from these weapons could lead to long-term global-scale environmental damage. For example, previous modeling studies of regional-scale nuclear exchanges have considered the emissions of reactive nitrogen and soot and shown that these can lead to a substantial loss of the global ozone burden. However, studies on urban fires suggest the fires in urban areas could also emit other key ozone-depleting substances, such as chlorine and bromine compounds released from the combustion of urban structures and industrial products. Moreover, recent studies on wildfires have shown that the increased solubility of hydrochloric acid in oxidized organic smoke particles could also greatly enhance the chlorine-driven ozone loss. For the first time, we use a climate-chemistry model with updated stratospheric chemistry that accounts for the effects of smoke particles on heterogeneous halogen chemistry to simulate the impacts of regional-scale nuclear wars on global climate and the ozone layer. Our results show that a regional war scenario with 5 Tg of soot emissions could result in approximately a 40% reduction in the global ozone burden within the first year of the simulation. This represents a ~50% greater ozone reduction compared to estimates from previous studies of similar nuclear war scenarios, when updated heterogeneous chemistry — specifically, HCl solubility on smoke particles and halogen emissions — is implemented. We have also examined changes in surface UV radiation resulting from the ozone loss and shown that even a regional-scale nuclear war could lead to severe global ozone depletion, posing grave risks to humanity and global ecosystems.
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