Late glacial Holocene sea surface temperatures and gradients between the North Atlantic and the Norwegian sea: Implications for the Nordic heat pump

A S-N transect of sediment cores is used to (a) determine the millenial scale variability of sea surface temperatures (SSTs) and (b) the strength of the S-N SST gradients in the North Atlantic. The results show that the initial warming of the surface North Atlantic after the Last Glacial Maximum occurred synchronously between 50°N and 63°N at 13.4 ka, but was delayed by 1000 years at 72°N. All cores indicate that the Bølling-Allerød period was a climatically unstable time interval punctuated by several SST coolings. However, the magnitudes of these brief coolings were strongly subdued in the North Atlantic compared with the eastern Norwegian Sea. Plotting SSTs on a S-N transect indicates the presence of a strong (9°C) gradient (the Arctic front) between the Norwegian Sea and the North Atlantic throughout the Bølling-Allerød period. This gradient became even stronger (15°C) during the Younger Dryas, and nearly disappeared during the Early Holocene. The observed SST gradients have implications for the magnitude of the oceanic heat pump and atmospheric circulation patterns of the late glacial period.