Barents Sea atlantification driven by a shift in atmospheric synoptic timescale

Climate change impinges on the Arctic Ocean, leading to sea-ice loss and potentially drastic cascading ecosystem changes. A recent process is atlantification, the growing influence of warm and salty waters from the Atlantic on the Arctic with increasing ocean volume transport from the Nordic Seas to the Barents Sea playing a key role. Despite its importance and a multitude of hypotheses that have been tested, this trend remains mainly unexplained. Here we explore nonlinear effects and successfully link the flow trend through the Barents Sea Opening to a frequency shift of atmospheric synoptic. We show that a part of the flow through Barents Sea Opening is driven by topographic Rossby waves, and that they have a very sensitive response to atmospheric frequency over the Nordic Seas. These findings highlight how anthropogenic changes to the atmosphere are altering ocean processes, with implications for sea-ice extent and ecosystems in the Arctic.