Sea level rise and fall north of Greenland reorganize Arctic freshwater export to North Atlantic.

Abstract

Arctic freshwater is exported to the North Atlantic through Fram Strait and the Canadian Arctic Archipelago, and its partitioning influences subpolar ocean stratification. How climate warming will alter these export pathways remains unclear. Here we show that dynamic sea level north of Greenland initially rises as the Beaufort Gyre freshens, but falls again as saltier Eurasian waters intrude once global warming exceeds approximately 3 K above preindustrial levels. This nonmonotonic sea-level evolution reorients surface geostrophic circulation north of Greenland and reorganizes Arctic liquid freshwater export pathways. As a result, the share of Arctic Ocean volume export through Fram Strait increases by about 40% before declining again. Satellite observations already indicate rising sea levels in the Last Ice Area, suggesting that this transition may be underway and that Fram Strait is emerging as a major Arctic export gateway for liquid freshwater and associated chemical tracers. Such changes could have important implications for North Atlantic salinity, biogeochemistry, and climate.