It is important to appreciate that the observed trend in Arctic sea ice cover over a given period is composed of a contribution caused by anthropogenic emissions, denoted the forced response, and a contribution from unforced fluctuations associated with internal climate variability (Dörr et al.,
2023; England,
2021; England et al.,
2019; Shen et al.,
2024; Sweeney et al.,
2024). Anthropogenically-forced changes which may contribute to a reduction in Arctic sea ice loss over the past two decades include a forced slowdown in the Atlantic Meridional Overturning Circulation (Lee & Liu,
2023), and changes in the emissions from biomass burning, both in the magnitude (Blanchard-Wrigglesworth et al.,
2025), and the variability (DeRepentigny et al.,
2022). One would imagine, however, that the reduction of sulfur emission from shiptracks (Yoshioka et al.,
2024) would lead to an acceleration rather than a deceleration of sea ice loss since 2020. Alternatively modes of climate variability which act on multi-decadal timescales, such as the Atlantic Multi-decadal Oscillation (Deser & Phillips,
2021; Kerr,
2000) and the Pacific Decadal Oscillation (Mantua & Hare,
2002), have an important imprint on Arctic sea ice. For example, variability emanating from the Pacific sector (Baxter et al.,
2019; Ding et al.,
2018) or Atlantic sector (Meehl et al.,
2018) has been suggested to have substantially contributed to the rapid loss of Arctic sea ice during the 2000s (England et al.,
2019). Several recent studies (Dörr et al.,
2023; Shen et al.,
2024; Siew et al.,
2024), based on different methods, conclude that internal variability is at least as important as anthropogenic forcing, perhaps more, for explaining the steep decline in that period. Needless to say, internal variability can damp sea ice loss trends as well as strengthen them. For instance, Yeager et al. (
2015) correctly predicted a slowdown of winter Atlantic sector sea ice loss for the past decade based on predictability from oceanic conditions linked to the North Atlantic Oscillation.