A high‐resolution diatom record of the last deglaciation from the SE Norwegian Sea: Documentation of rapid climatic changes

Abstract

Although the pulsating nature and the abruptness of the last deglaciation are well documented in marine and land records, very few marine records have so far been able to capture the high‐frequency climatic changes recorded in the Greenland ice core Dye 3. We studied high‐resolution sediment cores from SE Norwegian Sea, which display a detailed climatic record during the last deglaciation comparable to that of Dye 3. Accelerator mass spectrometry age control of the cores enables us to correlate this record in detail with continental records. The results indicate that the surface waters of the SE Norwegian Sea were seasonally ice free after 13,400 B.P. The Bølling/Allerød interstadial complex (13,200–11,200 B.P.) was a climatically unstable period with changing Arctic‐Subarctic conditions. This period was punctuated by four progressively more severe sea surface temperature (SST) minima: between 12,900–12,800 B.P. (BCP I); 12,500–12,400 B.P. (BCP II); 12,300–12,000 B.P. (OD I); and 11,800–11,500 B.P. (OD II). The Younger Dryas (YD) (11,200–10,200 B.P.) represents the severest and most prolonged cold episode of this series of climatic deteriorations. It was bounded by very rapid SST changes and characterized by Arctic‐Polar conditions. The first true warm Atlantic water incursion to the SE Norwegian Sea took place around 10,100 B.P., followed by a brief cooler condition between 9900–9600 B.P. (YD II). The early Holocene climatic optimum occurred between 8000–5000 B.P. A conceptual model is proposed where meltwater fluxes are suggested to cause the observed instability in the SST record.