Bertin, C., Miller, C.E., Carroll, D., Menemenlis, D., Zahn, M., and Wang, O. (2026)
Presented at:
Ocean Sciences Meeting 2026The Arctic is warming four times faster than the global average, with sea ice experiencing a dramatic decline and transitioning the Arctic Ocean to a new state in a series of tipping point events. To better understand sea-ice dynamics and improve future predictions, we analyze various sea-ice metrics — including extent (SIE), thickness (SIT), and phenology (SIP) — as simulated by the Estimating the Circulation and Climate of the Ocean (ECCO) circulation and sea-ice state estimate for the 1992–2024 period. Regional segmentation of these parameters reveals a significant regime shift between 2002 and 2008. This shift began with changes in SIP, likely driven by altered thermodynamics in seasonal sea-ice formation, which was followed by a shift in SIT and SIE. While the Central Arctic (CA) region did not exhibit similar shifting patterns in classic sea-ice parameters during the same period, a more subtle transformation was observed in the composition of multi-year ice (MYI). Between 2003 and 2010, sea-ice older than 3 years was widely replaced by 2-year old seasonal ice, indicating a shift in CA sea-ice composition. The lessons learned from this event inform our understanding of sea-ice regime shifts and valuable clues for anticipating future tipping points. Ocean state estimates, such as ECCO, represent powerful tools for guiding policy and support climate mitigation efforts.
