Distinct Impacts of Increased Atlantic and Pacific Ocean Heat Transport on Arctic Ocean Warming and Sea Ice Decline

Abstract Increased ocean heat transport (OHT) to the Arctic Ocean from the Atlantic and Pacific oceans contributes to Arctic Ocean warming and sea ice decline in a warming climate, processes known as Atlantification and Pacification, respectively. However, the separate impacts of these OHTs and their magnitudes remain unclear. This study uses a fully coupled climate model (FIO‐ESM v2.1) to investigate the specific impacts of increased Atlantic and Pacific OHTs on Arctic Ocean temperature, sea ice extent, and sea ice concentration. Our sensitivity experiments reveal that increased Atlantic OHT affects the temperature of the entire Arctic Ocean with the greatest impacts found in the Barents Sea and Eurasian Basin and at intermediate depths of the Arctic basin. The warming extent and efficiency from increased Atlantic OHT is considerably greater than that from Pacific OHT. Without warming of the Atlantic Water inflow, the rate of Arctic Ocean warming would decrease by approximately 50%. Increased Pacific OHT mainly affects the upper ocean in the Pacific sector, including the Chukchi Sea, East Siberian Sea, and Canada Basin. Increased OHT from both the Atlantic and Pacific oceans leads to notable sea ice decline with distinct regional and seasonal variations. Increased Atlantic OHT contributes to sea ice decline across most of the Arctic Ocean, particularly in the Barents Sea, the Kara Sea, and the central Arctic. In contrast, increased Pacific OHT leads to sea ice loss dominantly in the Pacific sector, including the Chukchi, the East Siberian, and the Beaufort seas.