Atlantification advances into the Amerasian Basin of the Arctic Ocean

Atlantification—the northward inflow of anomalous waters and biota from the Atlantic into the polar basins—has wide-ranging climatological ramifications.  Sustained observations demonstrated that, contrary to the global climate model projections, atlantification has already advanced into the Amerasian Basin of the Arctic Ocean, having a significant impact on the physical and ecological components of the climate system. The primary example is the rapidly diminishing sea ice in the Siberian Arctic Ocean (SAO), which is caused by the weakened ocean stratification and amplified heat fluxes. These sea ice thickness anomalies caused by atlantification persist across the Arctic region and are prevalent along the entirety of the Transpolar Drift. Furthermore, we observe the transition of the central SAO to conditions resembling those in the eastern SAO 5-7 years ago and the emergence of a powerful ocean-heat/ice-albedo feedback, which accelerates sea-ice losses. The eastern SAO is still strongly stratified but collaborative international observations demonstrate that the atlantification-driven shoaling of warm, salty, and nutrient-rich intermediate waters already has important ecological consequences there. Disentangling the role of atlantification in multiple and complex high-latitude changes should be a priority in future modeling and observational efforts.