Record of Holocene palaeoclimate change along the Antarctic Peninsula: evidence from glacial marine sediments, Lallemand Fjord

Abstract

In light of recent warming and environmental changes observed on the Antarctic Peninsula, an increased knowledge of regional palaeoclimatic trends may provide an improved understanding of the expected response of the Antarctic glacial, oceanic and biotic systems to continued warming. Sedimentologic and geochemical analyses of a 5.5 m long, high-resolution sediment core (PD92 GC-1), collected in Lallemand Fjord, represent the most detailed record of Holocene climate change, to date, in Antarctica. Grain size, smear slide analysis, magnetic susceptibility and total organic carbon content (TOC) were measured. One radiocarbon date establishes a chtonology for the base of the core. Correlation with the upper portion of core GC-1 with other cores collected in the fjord is based upon carbon stratigraphy, nine radiocarbon analyses and 2lOPb data. Deglaciation of Lallemand Fjord is believed to have occurred prior to 8000 yr BP, followed by a period of open marine conditions with variable extent of sea ice (variable TOC content) between 8000 and 2700 14C yr BP. A climatic optimum is recognised between 4200 and 2700 yr BP. Around 2700 yr BP, a decrease in TOC and diatom abundance reflects the formation of more extensive and seasonally persistent sea (fast) ice. The Muller Ice Shelf, now present in the fjord, advanced approximately 400 years ago, coincident with the Little Ice Age. These results indicate environmental variability throughout the Holocene that was consistent across most portions of the maritime Antarctic Peninsula. Surprisingly, the timing of climate transitions correlates with Northern Hemisphere "T-Events" and ice-core data from Greenland, indicating the possibility of coherent climate variability in the Holocene, at least for the high latitudes.