Drivers of propagation and impacts of meteorological and agricultural droughts across Europe

Droughts are Europe’s costliest natural disasters, with damages estimated at 621 million Euros per event. Changing precipitation patterns and rising atmospheric water demand are increasingly affecting terrestrial ecosystem functioning in Europe, with profound implications for sustainable water resources management and ecosystem carbon uptake. However, responses are driven not only by drought type and severity but also by diverse land surface properties, including soil texture and vegetation functional traits. A clear understanding of how water deficits propagate to inhibit ecosystem functioning is needed to assess drought risk for specific ecosystems under a warming climate. This study uses Community Land Model v5 (CLM5) simulations over Europe from 1960 to 2024 to identify drought events as spatiotemporal clusters and to systematically determine their propagation across hydrological compartments (e.g., from precipitation to root-zone soil moisture) and their impacts on gross primary production (GPP) and transpiration (T). We find that precipitation droughts often propagate into soil moisture droughts, especially during large-scale droughts, such as in the years 1995, 2003, and 2018. However, soil moisture droughts can also emerge even when precipitation deficits are not typically classified as drought events, for example, when vapor pressure droughts increase evaporation over a prolonged period. Further, we compare trends of drought characteristics and show increasing dynamics in the propagation of vapor pressure droughts and increasing severity of soil moisture droughts. These anomalies interact across multiple time scales to drive a wide, though predominantly negative, range of GPP and T responses: Short-term anomalies can already cause significant impacts on dry ecosystems and grasslands, while having only minor effects in humid ecosystems. These results are essential for understanding ecosystem-specific impacts during discrete drought events and for identifying ecosystems whose functioning is under increased risk as drought frequency and severity increase under climate change in Europe, essentially supporting EU Adaptation Strategy and the Water Framework Directive.