[A-CG42] 地球規模環境変化の予測と検出

[ACG42-01] Projections of Amazon dieback beyond the 21st century using Earth system models

*Irina Melnikova¹、Hideo Shiogama¹、Tomohiro Hajima²、Michiya Hayashi¹、Akihiko Ito³、Kazuya Nishina¹、Kaoru Tachiiri²、Tokuta Yokohata¹ (1.National Institute for Environmental Studies (NIES), Japan、2.Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Japan、3.The University of Tokyo, Japan)

キーワード：Amazon, carbon cycle , projection, tipping point

The Amazon rainforest, the world’s largest tropical forest, plays a critical role in the global carbon cycle and climate regulation but it faces risks of dieback under climate change. Here, we examine the Amazon dieback simulated by the Earth System Models using outputs of historical and RCP8.5 / SSP5-8.5 experiments from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6), extending into the 23rd century. Nine out of twelve models project dieback within the Amazon basin, with variations in timing and spatial extent. Most ESMs project the onset of the localised Amazon dieback in the 21st century, triggered by increased annual local surface air temperature and decreased precipitation, further exacerbated by land-use change. We identify the large-scale atmospheric circulation changes that contribute to regional reductions in precipitation and increases in temperature and examine the ecosystem processes that contribute to the dieback. Our findings offer critical insights into the mechanisms driving potential Amazon dieback and emphasize its consequences.