The observed sea ice concentration (SIC) over the Arctic has receded substantially in recent decades, and future model projections predict a seasonally ice-free Arctic in the second half of this century. Nevertheless, the impact of the Pacific on Arctic sea ice projections has yet to receive much attention. Observations show that summertime Arctic SIC growth events are related to the weakening of the Aleutian low and cooling events over the equatorial Pacific, and vice versa. We demonstrate that under various Coupled Model Intercomparison Project Phase 6 projections, the models in which the impact of El Niño-driven SIC loss is significantly higher than the La Niña-related SIC growth tend to turn seasonally ice-free by about 10–20 years ahead of the ensemble mean under high-emission future scenarios. We show how the non-linear impact of the El Niño Southern Oscillation (ENSO) on Arctic SIC resulted in a faster decline of summertime sea ice. The ENSO-related SIC changes in the multi-model ensemble mean of Arctic SIC are considerably lower than the internal variability and anthropogenic-driven changes. However, the asymmetric interannual ENSO effects over several decades and the resultant changes in surface heat fluxes over the Arctic lead to significant differences in the timing of sea ice extinction. Our results suggest that climate models must capture the realistic tropical Pacific–Arctic teleconnection to better predict the long-term evolution of the Arctic climate.

中文翻译：

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揭示热带太平洋对无冰北极预测的出现的作用

近几十年来，观测到的北极海冰浓度（SIC）已大幅下降，未来的模型预测预计本世纪下半叶北极将出现季节性无冰。然而，太平洋对北极海冰预测的影响尚未引起太多关注。观测表明，夏季北极SIC增长事件与阿留申低压减弱和赤道太平洋变冷事件有关，反之亦然。我们证明，根据各种耦合模型比对项目第 6 阶段的预测，厄尔尼诺驱动的 SIC 损失的影响显着高于拉尼娜相关的 SIC 增长的模型往往会在大约 10-20 年内变得季节性无冰。领先于未来高排放情景下的整体平均值。我们展示了厄尔尼诺南方涛动 (ENSO) 对北极 SIC 的非线性影响如何导致夏季海冰更快减少。北极 SIC 多模式集合平均值中与 ENSO 相关的 SIC 变化远低于内部变率和人为驱动的变化。然而，几十年来不对称的ENSO效应以及由此引起的北极地表热通量的变化导致海冰消亡的时间存在显着差异。我们的结果表明，气候模型必须捕捉现实的热带太平洋-北极遥相关，以更好地预测北极气候的长期演变。