Human influence on meteorological drought risk in Europe

Abstract:

Drought has affected 37% of the European Union’s territory in the past three decades, triggering ecological and socio-economic damages and impacting more than 100 billion inhabitants. Climate change simulations project increased drought risk in southern Europe, and on the other hand decreased drought risk in the norther of the continent. Observed changes in water balance components and drought indicators do resemble the projected pattern. However, assessments of possible causes of the reported regional changes have yet been inconclusive. To resolve this, we first employ a data driven approach and estimate how the probability of exceptionally dry years is related to global warming. The results confirm that it is very likely that that drought risk in the Mediterranean has increased in response to global warming, whereas it is very likely that drought risk has decreased in Northern Europe. Subsequently we show that observed changes in drought risk can only be captured by climate models if anthropogenic radiative forcing is accounted for. The consistency of the observational estimates with model simulations suggests that it is very likely that past changes in drought risk are attributable to anthropogenic effects on the climate.