Global Assessment of Compound Tropical Cyclone-Heat Hazards in a Changing Climate

Tropical cyclones (TCs) and extreme heat each pose risks to the public individually, and even more so in combination. TCs cause strong winds, intense precipitation, and storm surges that can result in widespread destruction and death. TCs often lead to power outages, which increases the risk of extreme heat exposure by preventing cooling from air conditioners and fans. With projected increases in frequency and intensity of heat extremes, coupled with the expected rise in TC intensity due to anthropogenic climate change, understanding the joint hazard of TC-heat compound events is essential for assessing future risks posed to human health. Prior studies have employed observations and statistical-dynamical TC models to explore TC-heat risks, but there is still limited understanding of these compound event hazards across the globe. To better understand the present and future risks of TC-heat compound events, we use the GFDL CM2.5-FLOR (FLOR) global climate model (50 km resolution atmosphere and land). FLOR is a fully dynamical, TC-permitting model that may offer a more realistic representation of TC-heat compound events by providing a larger sample size of events compared to the historical record and capturing the dynamical processes that may couple TCs and extreme heat. We conduct a comprehensive global analysis of past and present TC-heat compound events, utilizing a 10-member ensemble of FLOR historical simulations, validated against historical observations. This analysis allows for assessment of the hazards posed by TC-heat compound events under current climatic conditions. We also investigate the future behavior of TC-heat events under a warming scenario by employing a FLOR ensemble following RCP4.5. We identify high-risk areas for TC-heat compound events and examine how spatial patterns of risk may change from the past and present into the future. This project constrains the risk of these poorly understood compound TC-heat events over a broader region, to inform hotspots of risk, and motivate applicable extreme weather warning systems and adaptation strategies in the present and with climate change.