Implications of CMIP6 projected drying trends for 21st century Amazonian
drought risk
Abstract
Recent exceptionally hot droughts in Amazonia have highlighted the
potential role of global warming in driving elevated fire risk and
forest dieback. The previous generation of global climate models
projected that eastern Amazonia would receive less future rainfall while
western Amazonia would receive more rainfall, but many of these models
disagreed on the sign of future precipitation trends in the region. Here
Coupled Modeling Intercomparison Project, Phase 6 (CMIP6) models are
used to examine the shifting risk of eastern Amazonian droughts under
climate change. This new generation of models shows better agreement
that the entire Amazonian basin will receive less future rainfall, with
particularly strong agreement that eastern Amazonia will dry in the 21
century. These models suggest that global warming may be increasing the
likelihood of exceptionally hot drought in the region, and by
mid-century with unabated global warming, recent particularly warm and
severe droughts will become more common. However, Amazonia is a region
with a relatively sparse instrumental record that makes it difficult to
test the ability of model simulations to reproduce observed long-term
rainfall trends, and climate models have traditionally struggled to
reproduce satellite-era observed trends in the region. These
shortcomings highlight the need to improve confidence in global climate
models’; ability to simulate future drought, even if more CMIP6 models
agree on the sign of future rainfall trends.