EGU22-1204, updated on 27 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Less-deadly heatwaves due to soil drought

Hendrik Wouters1,2, Jessica Keune1, Irina Y. Petrova1, Chiel C. van Heerwaarden3, Adriaan J. Teuling4, Jeremy S. Pal5,6, Jordi Vilà-Guerau de Arellano3, and Diego G. Miralles1
Hendrik Wouters et al.
  • 1Hydro-Climate Extremes Lab, Ghent University, Ghent, Belgium (
  • 2Environmental Modelling Unit, Flemish Institute for technological Research, Mol, Belgium (
  • 3Meteorology and Air Quality Group, Wageningen University & Research, Wageningen, Netherlands.
  • 4Hydrology and Quantitative Water Management Group, Wageningen University & Research, Wageningen, Netherlands.
  • 5Department of Civil Engineering and Environmental Science, Loyola Marymount University, Los Angeles, United States.
  • 6Euro-Mediterranean Center on Climate Change and Ca’ Foscari University, Venice Marghera, Italy.

Global warming increases the number and severity of deadly heatwaves. Recent heatwaves often coincided with soil droughts that acted to intensify air temperature but lower air humidity. Since lowering air humidity may reduce human heat stress, the net impact of soil desiccation on the morbidity and mortality of heatwaves remains unclear. Combining weather balloon and satellite observations, atmospheric modelling, and meta-analyses of heatwave mortality, we find that soil droughts—despite their warming effect—lead to a mild reduction in heatwave lethality. More specifically, morning dry soils attenuate the afternoon heat stress anomaly by ~5%. This occurs due to reduced surface evaporation and increased entrainment of dry air from aloft. The benefit appears more pronounced during specific events, such as the Chicago 1995 and Northern U.S. 2006 and 2012 heatwaves. Likewise, our findings suggest that irrigated agriculture may intensify lethal heat stress, and question recently proposed heatwave mitigation measures involving surface moistening to increase evaporative cooling.

The manuscript of the findings is in press for Science Advances.




How to cite: Wouters, H., Keune, J., Petrova, I. Y., van Heerwaarden, C. C., Teuling, A. J., Pal, J. S., Vilà-Guerau de Arellano, J., and Miralles, D. G.: Less-deadly heatwaves due to soil drought, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1204,, 2022.