Drivers of Changing Interannual Variability in Autumn‐Early Winter Arctic Sea Ice (1950–2024)

Abstract Arctic sea ice has undergone a pronounced decline over recent decades, yet the drivers of its interannual variability remains unclear. Here we utilize standard deviation to assess long‐term changes in autumn‐early winter (October–December) Arctic sea ice concentration (SIC) variability from 1950 to 2024. The results reveal strong regional contrasts: interannual SIC variability has increased across the Arctic Ocean but decreased in several marginal regions. Much of the change arises from shifts in the sea ice state. In the Arctic Ocean, declining SIC and thinning ice have made the pack more sensitive to year‐to‐year forcing, whereas in the Atlantic and Pacific marginal seas, SIC has already fallen to levels that inherently limit the magnitude of interannual fluctuations. Enhanced variability in the Arctic Ocean is further linked to increased variability in ocean heat content. In contrast, reduced variability in the marginal seas corresponds to declining variability in key atmospheric and oceanic drivers.