Direct and seasonal legacy effects of the 2018 heat wave and drought on European ecosystem productivity

Authors: A Bastos and P Ciais and P Friedlingstein and S Sitch and J Pongratz and L Fan and J P Wigneron and U Weber and M Reichstein and Z Fu and P Anthoni and A Arneth and V Haverd and A K Jain and E Joetzjer and J Knauer and S Lienert and T Loughran and P C McGuire and H Tian and N Viovy and S Zaehle
Journal: Science Advances
Year: 2020

In summer 2018, central and northern Europe were stricken by extreme drought and heat (DH2018). The DH2018 differed from previous events in being preceded by extreme spring warming and brightening, but moderate rainfall deficits, yet registering the fastest transition between wet winter conditions and extreme summer drought. Using 11 vegetation models, we show that spring conditions promoted increased vegetation growth, which, in turn, contributed to fast soil moisture depletion, amplifying the summer drought. We find regional asymmetries in summer ecosystem carbon fluxes: increased (reduced) sink in the northern (southern) areas affected by drought. These asymmetries can be explained by distinct legacy effects of spring growth and of water-use efficiency dynamics mediated by vegetation composition, rather than by distinct ecosystem responses to summer heat/drought. The asymmetries in carbon and water exchanges during spring and summer 2018 suggest that future land-management strategies could influence patterns of summer heat waves and droughts under long-term warming.