Atmosphere-driven processes in shaping long-term climate variability in Greenland and the broader subpolar North Atlantic

The subpolar North Atlantic (SNA) represents a key region for atmospheric and oceanic heat exchange between the Arctic and subarctic, as well as for the maintenance of the Atlantic Meridional Overturning Circulation. Observational datasets reveal signatures of low-frequency climate variability in the SNA over the past decades: a warming trend in sea surface temperatures and a rise in atmospheric pressure in the troposphere have been observed from the early 1990s to the early 2000s, followed by an apparent pause or even a reversal in these climatic trends. The detailed mechanisms of this multidecadal climate variability remain elusive due to complex interactions between the atmosphere, ocean, and ice, as well as remote forcing of atmospheric teleconnections in and around the region. In particular, CMIP6 climate models, forced by anthropogenic forcing, show diverse skill in simulating this decadal variability, indicating a possible role of internal atmosphere-ocean interactions in regulating the regional impact of anthropogenic forcing over the SNA. Here, we investigate the physical mechanisms underlying these processes by analyzing various model simulations and conducting a new model experiment forced by observed local SNA winds. Results reveal that regional atmospheric circulation, partially driven by remote forcing from the tropical Pacific, plays an important role in shaping both interannual and multidecadal climate variability in the SNA by modulating local atmosphere-ocean interactions and upper-ocean poleward heat transport around 45° N. This finding highlights the importance of large-scale atmospheric circulation in driving long-term climate variability over Greenland and the larger SNA region in the historical era.