Two studies that appeared in Nature Climate Change in 2018 give an insight into the future of droughts in Europe. Not only will higher evaporative demand lead to drier soils and less water availability, but the drier soils will also lead to higher temperature extremes.
In a study based on high-resolution offline (uncoupled) simulations of soil moisture conditions under different climate scenario’s, Samaniego and co-workers found that soil moisture drought will worsen in the future. They found that relative to the 1.5 K target from the Paris agreement, an increase of 3 K would increase drought area by 40% (±24%), which would also affect a much larger share of 42% (±22%) of the population.
A separate study by Rasmijn and co-workers in the same issue looked at the effect of soil moisture drought on temperature extremes. By using a new nudging technique in combination with a large ensemble of regional climate model simulations, they were able to simulate what would happen if the 2010 Russian heatwave would take place in a future climate. One of the most striking results of the study is that because of enhanced soil drying in a warmer climate, temperature extremes might increasing by over 8 °C over western Russia. This is several times more than the increase that would be expected based on changes in mean temperature only.
Both studies highlight important future changes in the European summer climate. Not only will higher temperatures lead to increased drought by increasing evaporative demand and accelerating soil drying (see figure above), but at the same time this accelerated soil drying will reduce evapotranspiration and enhance the sensible heat flux. The coupling between hydrological processes at the land surface and the atmosphere will thus not only lead to drier, but also to hotter summers in the future.
Further reading
Samaniego, L. et al. (2018), Anthropogenic warming exacerbates European soil moisture droughts. Nature Climate Change, 8, 421–426, doi:10.1038/s41558-018-0138-5.
Rasmijn, M. et al. (2018), Future equivalent of 2010 Russian heatwave intensified by weakening soil moisture constraints. Nature Climate Change, 8, 381–385, doi:10.1038/s41558-018-0114-0.
Teuling, A. J. (2018), A hot future for European droughts. Nature Climate Change, 8(5), 364–365,
doi:10.1038/s41558-018-0154-5.