Minimal influence of reduced Arctic sea ice on coincident cold winters in mid-latitudes
Minimal influence of reduced Arctic sea ice on coincident cold winters in mid-latitudes
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DOI：
10.1038/s41558-019-0551-4
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发表时间：
2019-09-01
影响因子：
30.7
通讯作者：
Bintanja, Richard
中科院分区：
文献类型：
--
作者：
Blackport, Russell;Screen, James A.;Bintanja, Richard
观测表明，区域海冰覆盖减少与年际时间尺度上中纬度寒冷的冬季相吻合。然而，目前还不清楚这些观察到的联系是否是因果关系，模型实验表明它们可能不是。在这里，我们采用两种独立的方法来推断观测和气候模型的因果关系，并协调这些数据来源。模型捕捉到了观测到的海冰减少与中纬度寒冷冬季之间的相关性，但只有当海冰减少与从大气到海洋的异常热传递相吻合时，这意味着大气正在推动损失。从物理为基础的方法的因果关系的推断是证实了领先滞后分析，表明环流驱动的温度异常之前，但不遵循，减少海冰。此外，在模拟实验中没有发现中纬度地区的冷却与强加的未来海冰损失。我们的研究结果表明，强有力的支持异常大气环流，同时驱动寒冷的中纬度冬季和温和的北极条件，减少海冰有一个严重的中纬度冬季的影响最小。
Observations show that reduced regional sea-ice cover is coincident with cold mid-latitude winters on interannual timescales. However, it remains unclear whether these observed links are causal, and model experiments suggest that they might not be. Here we apply two independent approaches to infer causality from observations and climate models and to reconcile these sources of data. Models capture the observed correlations between reduced sea ice and cold mid-latitude winters, but only when reduced sea ice coincides with anomalous heat transfer from the atmosphere to the ocean, implying that the atmosphere is driving the loss. Causal inference from the physics-based approach is corroborated by a lead-lag analysis, showing that circulation-driven temperature anomalies precede, but do not follow, reduced sea ice. Furthermore, no mid-latitude cooling is found in modelling experiments with imposed future sea-ice loss. Our results show robust support for anomalous atmospheric circulation simultaneously driving cold mid-latitude winters and mild Arctic conditions, and reduced sea ice having a minimal influence on severe mid-latitude winters.