Title: The North Atlantic Warming Hole and AMOC weakening
Abstract: In contrast to most of the global ocean, the surface waters in the central subpolar gyre in the North Atlantic are actually cooling. This, the "North Atlantic Warming Hole" (NAWH), has been cited as proof that the Atlantic Meridional Overturning Circulation (AMOC) is weakening, potentially leading to drastic cooling in Scandinavia. We'll look at the NAWH in models and observations. The results suggest instead the feature is an fundamentally an advective feature, stemming from anomalous freshwater entering the gyre, primarily from melting sea ice in the Labrador and Nordic Seas. Turbulent mixing acts to reduce the temperature, leading to density compensation. As such, the NAWH is not the result of reduced oceanic heat transport, but the temperature anomaly decreases initially in concert with AMOC. In the long term, the relation breaks down as atmospheric warming weakens the anomaly. The findings illustrate the importance of freshwater fluxes from high latitudes in altering the regional ocean circulation.