Towards Improved Global Heat Stress Projections by Accounting for Spatio-Temporally Compounding Risks

As climate change intensifies, heat extremes pose an increasing threat to human health, leading to heightened morbidity and mortality particularly among vulnerable populations.

Physiological evidence demonstrates that high humidity exacerbates heat strain by impairing the body’s ability to thermoregulate through sweat evaporation. Therefore, metrics such as the wet bulb temperature, which combine both temperature and humidity effects, are commonly used to assess heat-related health risks, highlighting tropical and other humid regions as particularly at risk, while regions dominated by dry heat in the mid-to high latitudes appear comparatively less affected.

However, the tens of thousands of excess deaths caused by prolonged exposure to high ambient temperatures during e.g. recent record-breaking European heatwaves in 2003 and 2022 suggest that heatwave characteristics beyond temperature and humidity might need to be accounted for to accurately capture severe health impacts under dry heat conditions.

Here, we propose to enhance global heat stress assessments by addressing emerging spatio-temporally compounding features of heat extremes, which could greatly aggravate health impacts but due to their complexity are often not considered. Preliminary results will be presented from our efforts to develop a standardized, impact-focused heat stress metric that provides more robust and consistent assessments across diverse regional and climatic settings by integrating the cumulative effects of prolonged and sequential heat exposure.