Abstract
Humid heat and associated heat stress have increased in frequency, intensity, and duration across the world. Furthermore, extreme heat disproportionately affects vulnerable groups such as lower-income individuals and workers in industries that require outdoor labor (e.g., agriculture). A robust metric for heat stress impacts on the human body is wet bulb globe temperature (WBGT), because it incorporates wind speed and solar radiation in addition to temperature and humidity. Although WBGT can typically only be measured using non-standard instrumentation, estimation formulas have been developed to calculate WBGT using standard surface meteorological variables. This study employs the Liljegren WBGT estimation formula, which previous work found to be accurate with respect to observations. Using ERA5-Land reanalysis data, trends (1950-2023) in summer average and extreme daily maximum and minimum WBGT across Europe will be presented, including examinations of extreme event frequency and duration. Subsequently, the importance of each WBGT component (temperature, humidity, wind speed, solar radiation) to overall trends is quantified. Finally, WBGT trends are compared to those in ECMWF's Universal Thermal Comfort Index (UTCI), and the importance of sub-continental social vulnerability is discussed with respect to humid heat impacts on human health and mortality.
About the speaker
Dr. Shawn Milrad is an Associate Professor of Meteorology at Embry-Riddle Aeronautical University in Daytona Beach, Florida, USA. He is also currently a U.S. Fulbright Scholar to Norway, through which he is a guest researcher at the Geophysical Institute and Bjerknes Centre for Climate Research at the University of Bergen. Dr. Milrad has spent this semester at GFI/Bjerknes investigating trends in humid heat and associated human vulnerability across Europe, while also exploring all of Western Norway's beautiful landscape and culture.