The Amazon basin experienced a prolonged drought condition during the 2010s, leading to a large-scale forest degradation destructive to ecosystems and human society. Elusive are issues as to whether the decadal drought is driven by external forcing or internal variability, and whether the drought will continue or recover soon. Using large ensemble simulations from a state-of-the-art climate model, here we find a negative-to-positive phase transition of the Interdecadal Pacific Oscillation (IPO) explains ~45% (~40–49%) of the observed decadal drought of Amazon rainfall since 2010, much greater than the role of external forcing (~12%). Constraining future IPO phase transition reduces the uncertainty by ~38% from a range of −0.73 to + 0.31 mm day⁻¹ decade⁻¹ to a range of −0.42 to + 0.23 mm day⁻¹ decade⁻¹, of the near-term Amazon rainfall projection before 2040 under a mid-intensity emission scenario. Thus, the IPO plays a crucial role in the post-2010 drying and the near-term rainfall projection.

2010年代，亚马逊流域经历了长期干旱，导致森林大规模退化，对生态系统和人类社会造成破坏。十年期干旱是由外部强迫还是内部变率驱动，以及干旱是否会持续或很快恢复等问题难以捉摸。使用来自最先进的气候模型的大型集合模拟，我们发现年代际太平洋涛动 (IPO) 从负到正的相变解释了观测到的年代际的约 45% (约 40–49%) 2010年以来亚马逊降水干旱，远大于外强迫作用（~12%）。限制未来 IPO 阶段过渡可将近期的不确定性从 -0.73 至 + 0.31 mm day ^-1 October ^-1的范围降低至 -0.42 至 + 0.23 mm day ^-1 December ^-1的范围约 38%中等强度排放情景下 2040 年之前的亚马逊降雨量预测。因此，IPO对于2010年后的干旱和近期降雨预测起着至关重要的作用。