Northeast Greenland speleothems trap forest pollen during MIS

Diminishing ice sheets, an intensification of the hydrological cycle, and shifts in vegetation composition and abundance, are some of the results of the Arctic’s amplified response to climate warming. Improved understanding of Arctic amplification can be achieved through investigation of past interglacial periods. Although an increasing number of studies exploring past interglacials in Greenland exist, northeastern Greenland remains under-investigated, despite being highly sensitive to the effects of Arctic amplification. Here, we investigate the palaeoenvironment under warmer and wetter climate conditions by using pollen trapped in speleothems that were deposited in northeastern Greenland (80°N, 22°W) during late Marine Isotope Stage (MIS) 11. The results are placed in the context of a sensitivity study into modern pollen compositions recorded in surface samples as well as published Holocene records from eastern and northern Greenland. The deposition of speleothems in northeastern Greenland during MIS 11 and the composition of the trapped pollen assemblages provide a first-order proxy for drastically different atmospheric and oceanic boundary conditions compared to today. Modern and Holocene pollen samples are dominated by open land vegetation (shrubs and herbs), whereas the MIS 11 speleothem-trapped pollen show an abundance of conifer trees, primarily fir and pine, as well as an array of deciduous trees, shrubs, and open land vegetation. These results are in agreement with findings from other studies investigating southern Greenland during MIS 11. The speleothems and trapped pollen used in this study thus provide direct terrestrial evidence for the presence of higher vegetation in northeastern Greenland during MIS 11 and indirectly help to constrain the extent of the ice sheet at that time.