National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado.
Ann N Y Acad Sci. 2019 Jan;1436(1):36-53. doi: 10.1111/nyas.13856. Epub 2018 May 28.
As assessed over the period of satellite observations, October 1978 to present, there are downward linear trends in Arctic sea ice extent for all months, largest at the end of the melt season in September. The ice cover is also thinning. Downward trends in extent and thickness have been accompanied by pronounced interannual and multiyear variability, forced by both the atmosphere and ocean. As the ice thins, its response to atmospheric and oceanic forcing may be changing. In support of a busier Arctic, there is a growing need to predict ice conditions on a variety of time and space scales. A major challenge to providing seasonal scale predictions is the 7-10 days limit of numerical weather prediction. While a seasonally ice-free Arctic Ocean is likely well within this century, there is much uncertainty in the timing. This reflects differences in climate model structure, the unknown evolution of anthropogenic forcing, and natural climate variability. In sharp contrast to the Arctic, Antarctic sea ice extent, while highly variable, has increased slightly over the period of satellite observations. The reasons for this different behavior remain to be resolved, but responses to changing atmospheric circulation patterns appear to play a strong role.
根据卫星观测评估，从 1978 年 10 月至今，所有月份的北极海冰范围都呈下降线性趋势，在 9 月融冰季末期最大。海冰也在变薄。范围和厚度的下降趋势伴随着明显的年际和多年际可变性，这是由大气和海洋共同作用的结果。随着冰层变薄，其对大气和海洋强迫的响应可能正在发生变化。为了支持更加繁忙的北极地区，人们越来越需要在各种时间和空间尺度上预测冰况。提供季节性预测的主要挑战是数值天气预报的 7-10 天限制。虽然一个无冰的北极海洋可能在本世纪内是很有可能的，但时间上存在很大的不确定性。这反映了气候模式结构的差异、人为强迫的未知演变以及自然气候变率。与北极形成鲜明对比的是，南极海冰范围虽然变化很大，但在卫星观测期间略有增加。这种不同行为的原因仍有待解决，但对不断变化的大气环流模式的响应似乎发挥了重要作用。
