Arctic sea ice has been declining over past several decades with the largest ice loss occurring in summer. This implies a strengthening of the sea ice seasonal cycle. Here, we examine global ocean salinity response to such changes of Arctic sea ice using simulations wherein we impose a radiative heat imbalance at the sea ice surface, inducing a sea ice decline comparable to the observed. The imposed perturbation leads to enhanced seasonal melting and a rapid retreat of Arctic sea ice within the first 5–10 years. We then observe a gradual freshening of the upper Arctic ocean that continues for about a century. The freshening is most pronounced within the central Arctic, including the Beaufort gyre, and is attributed to excess surface freshwater associated with the stronger seasonal sea ice melting, as well as a greater upper-ocean freshwater storage due to changes in ocean circulation. The freshening of the Nordic Seas can also occur via a distillation-like process in which denser saline waters with increased salinity are exported to the subtropical/tropical North Atlantic by meridional overturning circulation. Thus, enhanced seasonal sea ice melting in a warmer climate can lead to a persistent Arctic freshening with large impacts on the global salinity distribution.

过去几十年来，北极海冰一直在减少，夏季发生的冰损失最大。这意味着海冰季节性周期的加强。在这里，我们使用模拟来检查全球海洋盐度对北极海冰这种变化的响应，其中我们在海冰表面施加辐射热不平衡，导致与观察到的海冰下降相当。强加扰动导致季节性融化加剧和北极海冰在头 5-10 年内迅速退缩。然后我们观察到北冰洋上层海洋逐渐清新，持续了大约一个世纪。在北极中部，包括波弗特环流，变淡水最为明显，这归因于与季节性海冰融化更强烈相关的过量地表淡水，由于海洋环流的变化，上层大洋淡水储存量增加。北欧海的清新也可以通过类似蒸馏的过程发生，在这个过程中，盐度更高的浓盐水通过经向翻转环流被输出到亚热带/热带北大西洋。因此，在温暖的气候下，季节性海冰融化加剧会导致北极持续清新，对全球盐度分布产生重大影响。