Читать книгу Biogeography in the Sub-Arctic - Группа авторов - Страница 64

During the past decades it has become clear that the Greenland Ice Sheet was much larger than at present during the last glacial maximum, at ~21 ka BP. In the north‐west, the Greenland ice sheet coalesced with the Innuitian Ice Sheet that covered the Canadian Arctic Archipelago (Blake et al. 1992; Kelly and Bennike 1992; Bennike and Björck 2002). Studies of sediment cores and detailed bathymetrical surveys show that the margin of the Greenland Ice Sheet reached the edge of the continental shelf both in South‐East Greenland (Mienert et al. 1992), in central West Greenland (Ó Cofaigh et al. 2013), in North‐West Greenland (Dowdeswell et al. 2014; Slabon et al. 2016) and probably also in East Greenland (Winkelmann et al. 2010; Arndt et al. 2017; Laberg et al. 2017; Arndt 2018). In South Greenland, geophysical modelling implies that the margin of the ice sheet reached the shelf edge and even the highest mountains were glaciated (Bennike et al. 2002b). Jameson Land in central East Greenland is characterized by deep weathering and little glacial scouring, and Funder (1979) suggested that this area was ice free during the last glacial maximum. On the basis of surface exposure dating of glacial erratics, Håkansson et al. (2009) questioned this restricted extent, but Funder et al. (2011) maintained that Jameson Land was ice free. New surface exposure dating of bedrock surfaces in Jameson Land indicates that the area was ice‐covered during the last glacial maximum, but it was deglaciated already at ~18–21 ka (Håkansson et al. 2011). A major expansion of the Greenland ice sheet during the last glacial maximum is in accordance with results from ice core studies (Vinther et al. 2009; Simonsen et al. 2019). The temperature minimum during the last ice age is dated to ~25 ka BP in Greenland, at which time the mean annual temperature was ~23° lower than today (Dahl‐Jensen et al. 1998).