High‐resolution projections of evapotranspiration and water availability for Europe under climate change

Abstract

Evapotranspiration plays an essential role in estimating water balance, runoff and effective precipitation. To determine historical and projected water availability for Europe, we contribute high‐resolution (1 km) estimates of monthly and annual potential evapotranspiration (ET0) and actual evapotranspiration (AET0). In the ET0 calculation, the monthly and annual heat index I and annual α parameter were estimated following the Thornthwaite method, and AET0 was calculated using the Budyko approach. The variables were estimated for a climate normal period that largely precedes an anthropogenic warming signal (1961–1990), and for two CMIP5 multi‐model future projections (2011–2040 and 2041–2070). We project widespread and relatively uniform ET0 increases of around 50–100 mm by the 2020s and 75–125 mm by the 2050s for most of Europe. These values imply important changes that may affect runoff and groundwater recharge. AET0 was identified as important driver of water availability with more regional variability. Spatial mapping of changes relative to the normal baseline imply that all except northern parts of Europe are vulnerable to water deficits, with pronounced decrease expected in southern Europe. We provide high‐resolution maps and data as an important tool for future natural resources management and climate change mitigation planning.