Recent slowing of Arctic sea ice melt tied to multidecadal NAO variability
Cen Wang, Hui Su, Chengxing Zhai, Jianqiu Zheng, Shiwei Yu, Huisi Mo, Yanjia Wang, Linwei Jiang
Abstract
The reduction of Arctic sea ice concentration (SIC) is a key indicator of global warming. In September 2012, SIC reached its lowest recorded value. Since then, sea ice melt has slowed down, showing a linear trend of only −0.4±6.8%/decade from 2012 to 2023, compared to −11.3±3.3%/decade from 1996 to 2011. Here, we demonstrate that the recent slowdown in September sea ice melt is closely coupled with the multi-decadal variability of the preceding summer North Atlantic Oscillation (NAO), which has transitioned from the lowest point of its negative phase in the early 2010s to a positive phase. During this shift, decreased heat and moisture, along with reduced downward longwave radiation, have contributed to offsetting the long-term decline, leading to a slowdown in Arctic sea ice melting. Additionally, the Atlantic Multidecadal Oscillation plays a primary role in driving the interdecadal variability of the NAO and Arctic sea ice by modulating wave-mean flow interactions. This study shows that the slowdown in September Arctic sea ice loss is linked to the shift towards a positive phase of the North Atlantic Oscillation, which reduces heat and moisture transport and longwave radiation, partially offsetting the long-term decline of Arctic sea ice.