Evidence of localised Amazon rainforest dieback in CMIP6 models

Amazon forest dieback is seen as a potential tipping point under climate change. These concerns are partly based on an early coupled climate–carbon cycle simulation that produced unusually strong drying and warming in Amazonia. In contrast, the fifth-generation Earth system models (Phase 5 of the Co...

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Bibliographic Details
Published inEarth system dynamics Vol. 13; no. 4; pp. 1667 - 1675
Main Authors Parry, Isobel M, Ritchie, Paul D. L, Cox, Peter M
Format Journal Article
LanguageEnglish
Published Gottingen Copernicus GmbH 24.11.2022
Copernicus Publications
Subjects
Amazon River region
Analysis
Carbon cycle
Carbon dioxide
Climate change
Climate models
Deforestation
Dieback
Dry season
Drying
Forest fires
Forests
Global warming
Intercomparison
Modelling
Precipitation
Rain forests
Rainforests
Seasonal variation
Seasons
Surface temperature
Temperature
Trends
Vegetation
Amazon River region
Amazon Basin
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Summary:Amazon forest dieback is seen as a potential tipping point under climate change. These concerns are partly based on an early coupled climate–carbon cycle simulation that produced unusually strong drying and warming in Amazonia. In contrast, the fifth-generation Earth system models (Phase 5 of the Coupled Model Intercomparison Project, CMIP5) produced few examples of Amazon dieback under climate change. Here we examine results from seven sixth-generation models (Phase 6 of the Coupled Model Intercomparison Project, CMIP6), which include interactive vegetation carbon and in some cases interactive forest fires. Although these models typically project increases in area-mean forest carbon across Amazonia under CO2-induced climate change, five of the seven models also produce abrupt reductions in vegetation carbon, which indicate localised dieback events. The northern South America (NSA) region, which contains most of the rainforest, is especially vulnerable in the models. These dieback events, some of which are mediated by fire, are preceded by an increase in the amplitude of the seasonal cycle in near-surface temperature, which is consistent with more extreme dry seasons. Based on the ensemble mean of the detected dieback events we estimate that 7±5 % of the NSA region will experience abrupt downward shifts in vegetation carbon for every degree of global warming past 1.5 ∘C.
ISSN:2190-4987
2190-4979
2190-4987
DOI:10.5194/esd-13-1667-2022