Episodic Northward Transport Along Nares Strait Brings Anomalously Warm Water Into the Arctic Ocean

Abstract Nares Strait is one of the primary Arctic export pathways for sea ice and freshwater, connecting the Arctic Ocean to the subpolar North Atlantic. The southward transport along the strait, primarily driven by the higher sea level in the Arctic compared to Baffin Bay, has occasionally been observed to reverse. Using a regional, high‐resolution coupled sea ice‐ocean model, extensively evaluated with observations, we identified multiple wind‐driven reversal events, from 2002 to 2020. Locally wind‐driven reversals occur between September and October, under low sea ice concentration and strong, persistent southwesterly winds. They last up to 15 days. Stronger and longer reversals, which occur in December, last up to 25 days and are driven by large‐scale atmospheric circulation patterns that directly influence the ocean circulation south of the strait. During both types of events, pulses of heat between 2 and 5 TW enter the Arctic Ocean. Model data show that reversal events coincide with elevated sea surface height along the Greenland coast, altering current structure along Nares Strait and enhancing heat transport. This anomalous northward heat transfer could potentially impact the formation and stability of Nares Strait ice bridges and accelerate the retreat of marine‐terminating glaciers that drain into the strait. Events in 2010 and 2017 led to a ∼33% increase in modeled heat transport into Petermann Glacier fjord (relative to the 2002–2020 mean), one of the largest glaciers in the Northern Hemisphere. Future reversals could have a greater impact considering the increasing ocean warming observed and simulated within Kane Basin.