A majority of El Niño/Southern Oscillation (ENSO) events are preceded by the North Pacific Meridional Mode (NPMM), a dominant coupled ocean–atmospheric mode of variability. How the precursory NPMM forcing on ENSO responds to greenhouse warming remains unknown. Here, using climate model ensembles under high-emissions warming scenarios, we find an enhanced future impact on ENSO by the NPMM. This is manifested by increased sensitivity of boreal-winter equatorial Pacific winds and sea surface temperature (SST) anomalies to the NPMM three seasons before. The enhanced NPMM impact translates into an increased frequency of NPMM that leads to an extreme El Niño or La Niña. Under greenhouse warming, higher background SSTs cause a nonlinear evaporation–SST relationship to more effectively induce surface wind anomalies in the equatorial western Pacific, conducive to ENSO development. Thus, NPMM contributes to an increased frequency of future extreme ENSO events and becomes a more influential precursor for their predictability.

大多数厄尔尼诺/南方涛动 (ENSO) 事件之前都是北太平洋经向模式 (NPMM)，这是一种主要的海洋-大气耦合变率模式。对 ENSO 的前驱 NPMM 强迫如何响应温室效应仍然未知。在这里，使用高排放变暖情景下的气候模型集合，我们发现 NPMM 对 ENSO 的未来影响增强。这表现在三个季节前北方冬季赤道太平洋风和海面温度（SST）异常对NPMM的敏感性增加。增强的 NPMM 影响转化为导致极端厄尔尼诺或拉尼娜现象的 NPMM 频率增加。在温室变暖的情况下，较高的背景海温会导致蒸发-海温的非线性关系，从而更有效地诱发赤道西太平洋的地表风异常，有利于ENSO的发展。因此，NPMM 有助于增加未来极端 ENSO 事件的频率，并成为其可预测性更有影响力的前兆。