Evidence from Svalbard for near-freezing temperatures and climate oscillations in the Arctic during the Paleocene and Eocene

Until recently, the Arctic was assumed to be characterised by relatively warm conditions throughout the Early Cenozoic. However, recent investigations on deep-sea drilling cores from northern high latitudes, including the Arctic Ocean, give apparently contradicting results. Here we report the intermittent occurrence of certain temperature indicators in the Early Tertiary sedimentary sequence on Svalbard, which may represent the first direct northern high-latitude record of cold water temperatures for the early Cenozoic. Glendonites (calcite pseudomorphs after calcium carbonate hexahydrate) and erratics in otherwise fine-grained sediments require near-freezing temperatures and the presence of at least seasonal sea ice. This succession also contains coal seams and other warm climate indicators, but not on the same stratigraphical levels. These results imply the occurrence of cooling phases episodically during the warm background climate of the Paleocene and Eocene, suggesting that Arctic temperature variability was much greater than previously recognized.