Instrumental records suggest multidecadal variability in Arctic surface temperature throughout the twentieth century. This variability is caused by a combination of external forcing and internal variability, but their relative importance remains unclear. Since the early twentieth century Arctic warming has been linked to decadal variability in the Pacific, we hypothesize that the Pacific could impact decadal temperature trends in the Arctic throughout the twentieth century. To investigate this, we compare two ensembles of historical all-forcing twentieth century simulations with the Norwegian Earth System Model (NorESM): (1) a fully coupled ensemble and (2) an ensemble where momentum flux anomalies from reanalysis are prescribed over the Indo-Pacific Ocean to constrain Pacific sea surface temperature variability. We find that the combined effect of tropical and extratropical Pacific decadal variability can explain up to ~ 50% of the observed decadal surface temperature trends in the Arctic. The Pacific-Arctic connection involves both lower tropospheric horizontal advection and subsidence-induced adiabatic heating, mediated by Aleutian Low variations. This link is detected across the twentieth century, but the response in Arctic surface temperature is moderated by external forcing and surface feedbacks. Our results also indicate that increased ocean heat transport from the Atlantic to the Arctic could have compensated for the impact of a cooling Pacific at the turn of the twenty-first century. These results have implications for understanding the present Arctic warming and future climate variations.

仪器记录表明，整个 20 世纪北极地表温度存在数十年的变化。这种可变性是由外部强迫和内部可变性共同引起的，但它们的相对重要性仍不清楚。由于 20 世纪初北极变暖与太平洋的年代际变率有关，我们假设太平洋可能会影响整个 20 世纪北极的年代际温度趋势。为了研究这一点，我们将 20 世纪历史模拟的两个集合与挪威地球系统模型 (NorESM) 进行了比较：(1) 一个完全耦合的集合和 (2) 一个集合，其中再分析的动量通量异常被规定在印度- 太平洋限制太平洋海表温度变化。我们发现，热带和温带太平洋年代际变率的综合影响可以解释多达 50% 的北极观测到的年代际表面温度趋势。太平洋 - 北极连接涉及低对流层水平平流和沉降引起的绝热加热，由阿留申低压变化介导。这种联系在整个 20 世纪都被检测到，但北极地表温度的响应受到外部强迫和地表反馈的缓和。我们的研究结果还表明，从大西洋到北极的海洋热量输送增加可以弥补 21 世纪之交太平洋冷却的影响。这些结果对理解当前的北极变暖和未来的气候变化具有重要意义。