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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. [ABSTRACT FROM AUTHOR]

The article discusses the environmental conditions of the Amazon River Region in the 21st century. According to the author, highways, dams, and agriculture have contributed to the dieback of the Amazon forest, which in turn prompted conservation efforts to preserve the tropical forest and advance indigenous peoples' rights in the Amazon. Topics include the environmental impact of greenhouse gas (GHG) emissions on the loss of biodiversity in the Amazon, the ecological impact of Amazon dieback, such as an impairment of the Amazon's ability to regulate climate, and an overview of the World Bank's Amazon dieback report "Assessment of the Risk of Amazon Dieback."