The Southern Ocean is a primary heat sink that buffers atmospheric warming and has warmed substantially, accounting for an outsized portion of global warming-induced excess heat in the climate system. However, its projected warming is highly uncertain and varies substantially across climate models. Here, using outputs from Coupled Model Intercomparison Project phase six models, we show that Southern Ocean warming during the twenty-first century is linked to the change in amplitude of the El Niño–Southern Oscillation (ENSO). Models simulating a larger increase in ENSO amplitude systematically produce a slower Southern Ocean warming; conversely, a smaller increase in ENSO amplitude sees a stronger warming. The asymmetry in amplitude and teleconnection between El Niño and La Niña produce cumulative surface wind anomalies over the southern high latitudes, impacting Southern Ocean heat uptake. The magnitude of inter-model ENSO variations accounts for about 50% of the uncertainty in the projected Southern Ocean warming.

南大洋是缓冲大气变暖的主要散热器，并且已经大幅升温，占全球变暖引起的气候系统过热的很大一部分。然而，其预计的变暖是高度不确定的，并且在不同的气候模型中差异很大。在这里，使用耦合模型比对项目第六阶段模型的输出，我们表明 21 世纪的南大洋变暖与厄尔尼诺-南方涛动 (ENSO) 幅度的变化有关。模拟 ENSO 幅度较大增加的模型系统地产生较慢的南大洋变暖；相反，ENSO 幅度的较小增加会导致更强烈的变暖。厄尔尼诺和拉尼娜之间振幅和遥相关的不对称在南部高纬度地区产生累积的地表风异常，影响南大洋的热量吸收。模式间 ENSO 变化的幅度约占预测的南大洋变暖不确定性的 50%。