Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: A major challenge for global land surface models

We propose a detailed evaluation of the ability of the ISBACC (Interaction Soil–Biosphere–Atmosphere Carbon Cycle) land surface model to capture drought effects on both water and carbon budgets, comparing fluxes and stocks at two recent throughfall exclusion (TFE) experiments performed in the Amazon.

We also explore the model sensitivity to different water stress functions (WSFs) and to an idealized increase in CO₂ concentration and/or temperature. In spite of a reasonable soil moisture simulation, ISBACC struggles to correctly simulate the vegetation response to TFE whose amplitude and timing is highly sensitive to the WSF. Under higher CO₂ concentrations, the increased water-use efficiency (WUE) mitigates the sensitivity of ISBACC to drought.