Mid- to late-Holocene hydrological and climatic variability in Disko Bugt, central West Greenland

摘要

Diatom and lithological analyses were carried out on two sediment cores from Disko Bugt and the adjacent Kangersuneq Fjord, West Greenland, in order to investigate mid- to late-Holocene (6.9-0.7 kyr BP) hydrographic and climatic variability. While the Disko Bugt record is found to reflect mainly West Greenland Current (WGC) fluctuations that can be linked to North Atlantic circulation variability, the fjord record appears to be more representative of local climate conditions. The records demonstrate that the period of investigation was marked by a late-Holocene Thermal Maximum beginning at c. 4.8 kyr and ending between 3.5 and 3.1 kyr BP, encompassing a colder period between c. 4.0 and 3.8 kyr BP. An episode of higher surface-water temperature is also indicated in Disko Bugt between 2.2 and 1.5 kyr BP. In contrast, the record from Kangersuneq Fjord suggests persisting cooler (summer) surface waters for this interval, interpreted to be attributable to increased meltwater outflow. The warming episode recognized in Disko Bugt corresponds to a reported interval of increased influence of Atlantic waters in the East Greenland Current, which suggests an active North Atlantic current system with enhanced Irminger Current transport also affecting the WGC. Within the later part of the Disko Bugt record ending at c. 0.7 kyr BP (c. AD 1300) no evidence could be found for a significant Mediaeval warming. When comparing the timing of various environmental changes with past shifts in human settlement in the Disko Bugt area, an apparent link exists between changes in hunting tradition and sea ice conditions.