A Report on Assumptions and Uncertainties in Modeling Nuclear Winter

Madeline Berzak, Bennett Cullision, Yohana Eshetu, Nicolas Park

Nuclear winter is arguably the biggest consequence of a nuclear war that the field seeks to prevent; experts study nuclear winter to prevent civilizational collapse and widespread catastrophe. A nuclear winter would be, for lack of better words, really bad. As long as the risk of nuclear war exists, so too will the catastrophic risk of a nuclear winter. Much of the modeling and research that exists on nuclear winter relies on several outdated assumptions or has been altered to elicit a specific political response, thus exaggerating or downplaying the severity. The nuclear field often conflates the ‘politically irrelevant’ with the ‘scientifically resolved.’ When certain questions fall out of political relevance, the field most often stops investigating them and considers them solved.
Over time, the nuclear field has become more narrowly focused on preventing nuclear war, and because of this, the field has largely failed to more rigorously re-examine and update the scientific foundations of our understanding of how a nuclear winter occurs and behaves. This report interrogates current nuclear winter models, relevant literature, and prevalent scientific research to more clearly identify and understand the assumptions and uncertainties that underpin the field’s understanding of nuclear winter.
The broader goal is to identify assumptions in the literature and evaluate how strongly each assumption is supported. In identifying these assumptions and uncertainties throughout the different phases of the nuclear winter mechanism chain, we both replicated methodologies from past models and developed new methodologies and conclusions to determine the validity of the assumptions themselves. Informed by this research, we developed a more comprehensive research agenda on where the field’s understanding of nuclear winter falls flat, and how more recent and multidisciplinary research can bolster analysis more broadly.