Current climate models suggested that Antarctic sea ice cover would decrease substantially under cumulative CO₂ emission, but little is known whether large decrease in Antarctic sea ice can influence the occurrence of strong El Niño. Using time slice coupled and uncoupled model experiments, we show that in response to half reduction of Antarctic sea ice projected near the end of the 21st century, the frequency of strong El Niño would be increased by ~40%. It is contributed by enhanced thermocline, Ekman, and zonal advective positive feedbacks that are partly offset by enhanced thermodynamic damping. The strong warming and weakened westerly winds in the southeastern Pacific generate an anomalous Rossby wave propagating into the eastern subtropical and tropical Pacific, favoring stronger El Nino, and air-sea coupling and ocean feedbacks play a critical role in the teleconnection. Unexpectedly, compare to halved Antarctic sea ice, the ice-free Antarctic leads to a decrease in the frequency of strong El Niño, which is largely due to a substantial increase in thermodynamic damping. We also show that a large portion of the increase of strong El Niño events under greenhouse warming might be connected with Antarctic sea-ice loss, though increased greenhouse gas plays an important role.

目前的气候模型表明，在累积 CO₂ 排放的情况下，南极海冰覆盖将大幅减少，但南极海冰的大幅减少是否会影响强厄尔尼诺现象的发生，目前尚不清楚。使用时间片耦合和非耦合模型实验，我们表明，预计在 21 世纪末南极海冰减少一半，强厄尔尼诺现象的频率将增加 ~40%。它是由增强的温跃层、Ekman 和纬向平流正反馈贡献的，这些反馈部分被增强的热力学阻尼所抵消。东南太平洋的强烈变暖和减弱的西风产生了一个异常的罗斯比波，传播到东亚副热带和热带太平洋，有利于更强的厄尔尼诺现象，气海耦合和海洋反馈在遥相关中起着关键作用。出乎意料的是，与减半的南极海冰相比，无冰的南极导致强厄尔尼诺现象的频率降低，这主要是由于热力学阻尼的大幅增加。我们还表明，温室气体变暖下强厄尔尼诺事件的增加很大一部分可能与南极海冰损失有关，尽管温室气体的增加起着重要作用。