Drought-climate feedbacks: Model uncertainties and potential for surprises*

Droughts are complex phenomena resulting from the interaction of atmospheric and
land processes, including vegetation-controlled processes (e.g. Seneviratne et al.
2021). Recent analyses suggest that state-of-the-art Earth System Models (ESMs)
display some systematic biases in the representation of droughts and drought-
climate feedbacks. For instance, the representation of drying trends in West-Central
Europe appears to be generally underestimated compared to observational records
(Schumacher et al. 2024). In addition, current ESMs fail to capture an increasingly
negative correlation between terrestrial water storage anomalies in the tropics and
anomalies of the global CO 2 growth rate, which could reflect an enhanced soil
moisture limitation for vegetation in recent decades and/or changes in the
characteristics of ENSO events (Liu et al. 2023). Some important limitations of
current climate projections, both related to emissions scenarios and climate models,
are also associated with fire dynamics and plant mortality (Canadell et al. 2021;
Sanderson and Fisher, 2020; Jaeger et al, in review). Drought impacts on the carbon
cycle could play an important role in coming decades and need to be better
constrained to inform policymaking. Drought-temperature feedbacks are also highly
relevant for the occurrence of record-shattering heat extremes (Schumacher et al.
2022).