Zhang Rong
Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, NJ 08540
Proc Natl Acad Sci U S A. 2015 Apr 14;112(15):4570-5. doi: 10.1073/pnas.1422296112. Epub 2015 Mar 30.
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.
卫星观测显示，自1979年以来9月北极海冰范围大幅下降，这在近期观测到的北极表面变暖中起了主导作用，并且在很大程度上常常归因于温室气体的增加。然而，最迅速的下降发生在近期全球变暖停滞期。以往的研究往往聚焦于夏季北极海冰范围变化和变动的单一机制，而且许多研究基于较短的观测记录。对于年代际/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，目前还了解不足。据作者所知，这里首次建立了一个多元回归模型，以提供一个框架，利用长达3600年的控制气候模式模拟，量化三个关键预测因子（进入北极的大西洋/太平洋热量输送以及北极偶极）对夏季北极海冰范围内部低频变化的贡献。结果表明，这些关键预测因子的变化可能对观测到的夏季北极海冰减少有很大贡献。如果由于内部变率，未来进入北极的海洋热量输送减弱，9月北极海冰的减少可能会出现停滞。模型结果还表明，在年代际/百年时间尺度上，跨北极圈的大气热量输送变化是由进入北极的大西洋热量输送的反相关变化驱动的。
