The Weakened Atlantic Meridional Overturning Circulation Diminishes Recent Arctic Sea Ice Loss

• Published in: Geophysical research letters 2023-11, Vol.50 (21), p.n/a
• Main Authors: Lee, Yu‐Chi, Liu, Wei
• Format: Article
• Language: English
• Subjects: Ablation; Anthropogenic climate changes; Anthropogenic factors; Arctic sea ice; Arctic sea ice loss; Arctic zone; Atlantic meridional overturning circulation; Atlantic Meridional Overturning Circulation (AMOC); Circulation; Climate change; climate model simulation; Climate models; Climate system; Heat transport; Ice; Ice environments; Meteorological satellites; Ocean circulation; Ocean currents; Oceans; Salinity; Sea ice; Simulation; Trends; Water circulation
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL105929

The Arctic sea ice has been rapidly dwindling over the past four decades, significantly impacting the Arctic region and beyond. During the same period, the Atlantic meridional overturning circulation (AMOC) was also found in a declining trend. Here we investigate the role of the AMOC in the recent Arctic sea ice changes by comparing simulations from the Community Climate System Model version 4 with decelerated and stationary AMOCs under anthropogenic climate change. We find that the weakened AMOC can slow down the decline rates of Arctic sea ice area and volume by 36% and 22% between 1980 and 2020, respectively. The decelerated ocean circulation causes a reduction of northward Atlantic heat transport and hence a general interior ocean cooling in the Arctic Mediterranean, which helps alleviate the Arctic sea ice loss primarily through thermodynamic processes occurring at the base of the sea ice. Plain Language Summary Over the last 40 years, the Arctic sea ice cover has been shrinking rapidly, impacting not only the region but also areas beyond. At the same time, a significant weakening of the Atlantic meridional overturning circulation has been observed. We aim to understand how the Atlantic overturning influences these changes in Arctic sea ice. We use climate model simulations to compare between weakened and stable overturning circulation scenarios under human‐induced climate change. Our results reveal that a weaker Atlantic overturning can slow down the decline of Arctic sea ice area and volume by 36% and 22% during the period of 1980 and 2020, respectively. This weakening of ocean circulation reduces the northward flow of warm water, leading to cooling in the Arctic Ocean, which in turn helps mitigate the loss of sea ice, primarily through processes that take place at the base of the sea ice. Key Points This study clarifies the AMOC's impact on Arctic sea ice by using the CCSM4 climate model simulations with weakened and stationary AMOCs The weakened AMOC could decelerate the Arctic sea ice area and volume loss by 36% and 22% during 1980 and 2020, respectively Detailed sea ice volume budgets shows weakened AMOC promotes ice growth at base, aided by thermodynamic process