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

E. Joetzjer*, C. Delire, H. Douville, P. Ciais, B. Decharme, R. Fisher, B. Christoffersen, J. C. Calvet, A. C.L. Da Costa, L. V. Ferreira, P. Meir

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    35 Citations (Scopus)

    Abstract

    While a majority of global climate models project drier and longer dry seasons over the Amazon under higher CO2 levels, large uncertainties surround the response of vegetation to persistent droughts in both present-day and future climates. 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. While one of the proposed WSF formulations improves the response of most ISBACC fluxes, except respiration, a parameterization of drought-induced tree mortality is missing for an accurate estimate of the vegetation response. Also, a better mechanistic understanding of the forest responses to drought under a warmer climate and higher CO2 concentration is clearly needed.

    Original languageEnglish
    Pages (from-to)2933-2950
    Number of pages18
    JournalGeoscientific Model Development
    Volume7
    Issue number6
    DOIs
    Publication statusPublished - 10 Dec 2014

    Fingerprint

    Dive into the research topics of 'Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: A major challenge for global land surface models'. Together they form a unique fingerprint.

    Cite this