Mechanisms for low-frequency variability of summer Arctic sea ice extent
Mechanisms for low-frequency variability of summer Arctic sea ice extent
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DOI：
10.1073/pnas.1422296112
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
Rong‐Hua Zhang
中科院分区：
文献类型：
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作者：
Rong‐Hua Zhang
夏季北极海冰的减少通常被归因于温室气体的增加。然而，气候系统内部低频变率的贡献还没有得到很好的理解。本文首次建立了一个多元回归模型，定量分析了三个主要预报因子对夏季北极海冰范围内部低频变率的贡献。如果由于内部变化，海洋热量输送到北极的能力在不久的将来减弱，9月份北极海冰的下降可能会出现中断，并推迟实现夏季无冰的北极。这种具有广泛生态和经济影响的合理情景不应被忽视。卫星观测显示，自1979年以来，9月份北极海冰范围大幅减少，这在最近观测到的北极表面变暖中发挥了主导作用，通常在很大程度上归因于温室气体的增加。然而，最快的下降发生在最近的全球变暖间歇期。以往的研究往往集中在一个单一的机制，夏季北极海冰范围的变化和变化，许多是基于短期的观测记录。在几十年/百年时间尺度上夏季北极海冰范围变化的关键因素及其对观测到的夏季北极海冰减少的贡献还没有得到很好的理解。这里的多元回归模型是第一次开发，据作者所知，提供一个框架来量化的贡献的三个关键的预测（大西洋/太平洋热量输送到北极，北极偶极子）的内部低频变率的夏季北极海冰范围，使用3,600年长的控制气候模式模拟。结果表明，这些关键预测因子的变化可能对观察到的夏季北极海冰减少有很大贡献。如果由于内部变化，海洋热量输送到北极在不久的将来减弱，9月份北极海冰的下降可能会出现中断。模拟结果还表明，在几十年/百年的时间尺度上，在整个北极圈的大气热传输的变化被迫在大西洋热量输送到北极的变化。
Significance The observed decline in summer Arctic sea ice has often been attributed, in large part, to the increase in greenhouse gases. However, the contributions from internal low-frequency variability in the climate system are not well understood. Here a multiple regression model is developed for the first time, to the author’s knowledge, to quantify the contributions of three key predictors on the internal low-frequency variability of summer Arctic sea ice extent. If the ocean heat transport into the Arctic were to weaken in the near future due to internal variability, there might be a hiatus in the decline of September Arctic sea ice, and a delay in attaining a summer ice-free Arctic. This plausible scenario with broad ecological and economic impacts should not be ignored. Satellite observations reveal a substantial decline in September Arctic sea ice extent since 1979, which has played a leading role in the observed recent Arctic surface warming and has often been attributed, in large part, to the increase in greenhouse gases. However, the most rapid decline occurred during the recent global warming hiatus period. Previous studies are often focused on a single mechanism for changes and variations of summer Arctic sea ice extent, and many are based on short observational records. The key players for summer Arctic sea ice extent variability at multidecadal/centennial time scales and their contributions to the observed summer Arctic sea ice decline are not well understood. Here a multiple regression model is developed for the first time, to the author’s knowledge, to provide a framework to quantify the contributions of three key predictors (Atlantic/Pacific heat transport into the Arctic, and Arctic Dipole) to the internal low-frequency variability of Summer Arctic sea ice extent, using a 3,600-y-long control climate model simulation. The results suggest that changes in these key predictors could have contributed substantially to the observed summer Arctic sea ice decline. If the ocean heat transport into the Arctic were to weaken in the near future due to internal variability, there might be a hiatus in the decline of September Arctic sea ice. The modeling results also suggest that at multidecadal/centennial time scales, variations in the atmosphere heat transport across the Arctic Circle are forced by anticorrelated variations in the Atlantic heat transport into the Arctic.