Holocene sea-ice variations in Greenland: onshore evidence

Abstract

The oldest dated driftwood log from northern Greenland is c. 9300 cal. years old, which is about 2000 years younger than the beginning of the last deglaciation and 2000 years younger than the oldest driftwood on Svalbard. Driftwood entry to northern Greenland was rare until 7400 cal. years BP, indicating more severe summer sea-ice conditions than at present. More open water than at present probably characterized the period between 6800 and 5500 cal. years BP, during which time driftwood stranded on the beaches of Nioghalvfjerdsfjorden that is now covered by a floating glacier. In central East Greeland, the occurrence of the extralimital species Mytilus edulis in the time interval from c. 8500 to 6000 cal. years BP indicates more open water than at present, and in northwest Greenland studies of dinoflagellate cysts in a marine core indicate warmer surface waters, and hence less sea ice than at present from 7300 to 3700 cal. years BP.