Rising Heat, Rising Risks: Understanding the Nexus of Marine Heatwaves, Fishing Dependence, and Vulnerability to Coastal Communities.

Marine heatwaves are increasing in frequency, intensity, and duration as a result of climate change, and their biological impacts can in turn influence coastal communities. Despite advances in our knowledge of the physical drivers of marine heatwaves and their biological impacts, there has been limited work linking these extreme events to subsequent impacts on social systems. Describing risk to well-being in coastal communities from marine heatwaves requires the consideration of the severity of marine heatwaves, impacted systems, and social vulnerability. We compared potential risk to well-being, or quality of life, from 2012 to 2016 in coastal communities in the United States and Australia by considering marine heatwave total cumulative intensity, fishing dependence, and vulnerability indices. We extended a social indicators framework for the United States to develop vulnerability indices for coastal communities in Australia. Our approach revealed different spatial patterns in risk to well-being and its drivers between the two countries. Marine heatwaves as the hazard were a key driver of risk in both countries, and vulnerability for the United States and fishing employment for Australia were also influential. Our study demonstrates that risk does not necessarily equal the hazard, and there is non-transferability of risk results between countries despite similar physical oceanography and socioeconomic status. Identifying regions of high risk with our broad approach can help prioritize higher resolution community-level work to mitigate risk and develop adaptation pathways.