Extreme Heat and Rainfall Risk Attributed to Cumulative CO2 Emissions from Fossil Fuel Producers

Christopher Callahan

Legal and political approaches to climate accountability require demonstrating that a particular emitter contributed to a climate impact, but quantitative solutions to this attribution challenge remain nascent. This study leverages the proportionality of global warming to cumulative CO2 emissions to develop statistical models that directly predict extreme climate risk from cumulative emissions. Results show that cumulative emissions from individual actors have increased the probability of extreme heat and rainfall globally; for example, emissions from the United States have increased the risk of recent extreme heat by at least 50% for one-third of the globe. Focusing on specific events demonstrates that emissions from major fossil fuel firms increased the likelihood of the 2021 Pacific Northwest heat wave by 31% and 2022 extreme rainfall in Pakistan by 7%. These results demonstrate a flexible attribution framework grounded in the proportional relationships that inform climate policy, with the potential to guide efficient climate accountability assessments.