ANTARCTIC PENINSULA GLACIER SYNCHRONICITY INCREASED DURING THE HOLOCENE: IMPLICATIONS FOR THE MODERN RECESSION

Modern studies of glacier mass balance in the Antarctic Peninsula overwhelmingly demonstrate widespread recession of glaciers and ice shelves in recent decades. While the modern recession has been linked to rapid atmospheric warming and warm ocean currents, the pre-satellite era behavior of tidewater glaciers has yet to be documented on spatial and temporal scales that are comparable to these modern glaciological observations. Here we present the largest comparison to date of tidewater glacier advance and retreat since the Last Glacial Maximum, detailing timing of glacial behavior once the Antarctic Peninsula Ice Cap receded to the inner continental shelf and into bays and fjords. We examine the glacimarine sedimentary records from a dozen coastal embayments of the Antarctic Peninsula, spanning 11° of latitude and vastly different local climatic and oceanographic ranges, including those both east and west of the peninsula. In order to develop a holistic and comparable dataset, multiple proxies were used to evaluate glacial and marine conditions from these expanded sediment records, including sediment grain size, carbon and nitrogen content, and diatom and foraminiferal microfossil assemblages. Where published records lacked these data, cores were resampled for additional proxies. Radiocarbon AMS dating was used to develop a detailed chronology for each site, and sampling resolution on the sub-centennial scale was achieved within these expanded sedimentary archives, notably lacking bias in the older vs. younger intervals of the records. This novel comparison reveals that tidewater glaciers responded asynchronously to climate events during the Early and Mid Holocene, but synchronously to Late Holocene events as their drainage areas decreased in size. Progressive increase in synchronicity of glacial behavior throughout the Holocene implies that the retreating glacial systems are now exceptionally vulnerable to current atmospheric and ocean warming.