This project studies marine sediment cores from the Antarctic peninsula to determine whether the current decay of ice shelves there is caused by global warming or another cycle. A comprehensive set of core analyses?from radiocarbon to biostratigraphy?will be performed to characterize ice-shelf status during the last 20,000 years. The project?s goal is to assess ice-shelf response to environmental drivers such as ocean temperature, precipitation, and sea ice extent. The study benefits from two, recent, NSF-supported expeditions to the area, including ShalDril, in which lengthy sediment cores were collected. These cores will support development of a high-resolution picture of the peninsula?s glacial, climactic, and oceanographic history.
The broader impacts of this project include graduate and undergraduate participation in research, support for early career researchers, collaboration with primarily undergraduate institutions, and international collaboration with scientists in the UK and Poland. There are also implications for society?s understanding of climate change, since this work improves our understanding of the behavior of ice sheets and their links to global climate.
Paleoclimate records from eight fjords extending from the South Shetland Islands to Pine Island Bay were generated from long sediment cores aspart of an international study of Holocene climate change. These results are augmented by published records from more open marine settings of thePalmer Deep and the Bransfield Basin, as well as from land-based studies to obtain the spatial sampling needed to examine the timing of climate eventsand climate forcing mechanisms. The records are derived from sediment cores acquired during a 2007 cruise of the NBP Palmer and during an earlier 2005 SHALDRIL cruise when drill cores were acquiredfrom some of the thicker (up to 108 meters) Holocene sections in fjords ofthe northern Antarctic Peninsula (AP) region. Robust radiocarbon chronologies were obtained for one or more cores from all fjords and a number of paleoclimatic proxies have been applied to identify and characterize climate events. These include grain size, sedimentation rates, magnetic susceptibility, pebble content, TOC, biogenic silica content, and diatom and foraminiferal assemblages. Five previously recognized climate intervals are recorded throughout the AP: an early Holocene deglacialinterval, the Mid-Holocene Climate Optimum, a minor cooling event in the mid-Holocene followed by a minor warming event, and the late Holocene Neoglacial. The timing of these events varies widely, up to a few thousand years, across the AP region and reflects differences in local and regional factors such as orography, drainage basin size and altitude, wind patterns,oceanography, and sea-ice coverage. The combined results suggest that the rapid regional warming and glacialretreat observed during the last century is unprecedented in breadth and synchronicity in the Holocene. Although this grant is technically expired, one PhD student, Ms Rebecca Minzonni, continues to work on the project and supported by Rice University.Her research focuses on the analysis of Kasten cores, including using short-lived isotopes as an age dating tool,aimed at examining the magnitude and temporal variation of late Holoceneclimate change. Peer ReviewedPublications resulting from this grant Heroy, D.C., Sjunneskog, C., and Anderson, J.B., 2008, Holocene climate change in the Bransfield Basin, Antarctic Peninsula: evidence from sediment and diatom analysis, Antarctic Science, v. 20, p. 69-87. Milliken,K.T.,Anderson, J.B., Wellner, J.S., Bohaty, S.M., and Manley, P.L., 2009, High-resolution Holocene climate record from Maxwell Bay, South Shetland Islands, Geological Society of America Bulletin, v. 121, 1711-1725. K.T., Anderson, J.B., Wellner, J.S., Bohaty, S.M., and Manley, P.L., 2009, Michalchuk, B., Anderson, J.B., Wellner, J., Manley, P., Majewski, W., and Bohaty, S., 2009, Holocene climate and glacial history of the northeastern Antarctic Peninsula: the marine sedimentary record from a long shaldrill core, Quaternary SciencReviews, v. 28, p. 3049-3065. Allen, C.S., Oakes-Fretwell, L., Anderson, J.B., and Hodgson, D.A., 2010, A record of Holocene glacial oceanographic variability in Neny Fjord, Antarctic Peninsula, The Holocene, v. 20, p. 551-564 Majewski, W., and Anderson, J.B., 2009, Holocene foraminiferal assemblages from Firth of Tay, Antar551-ctic Peninsula: paleoclimatic implications, Marine Micropaleontology, v. 73, p. 135-147.. Lu, Z.L., Rickaby, R.E.M., Wellner, J., Georg, B., Charnley, N., Anderson, J.B., and Hensen, C., 2010, Pore fluid modeling approach to identify recent meltwater signals on the west Antarctic Peninsula: Geochemistry Geophysics Geosystems, v. 11, Q06017, doi:10.1029/2009GC002949. Milliken, K.T., Anderson, J.B., Wellner, J.S., Bohaty, S.M., and Manley, P.L., 2009, Lu, Z., Rickaby, R.E.M., Kennedy, H., Kennedy, P., Pancost, R.D., Shaw, S., Lennie, A., Wellner, JJ., and Anderson, J.B., 2012, An ikaite record of late Holocene climate at the Antarctic Peninsula, Earth and Planetary Science Letters, v. 325-326, p. 108-115. Majewski, W., and Anderson, J.B., 2009, Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: paleoclimatic implications, Marine Micropaoleontology, v. 73, p. 135-147. Majewski, W., and Anderson, J.B., 2009, Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: paleoclimatic implications, Marine Micropaleontology, v. 73, p. 135-147.. Majewski, W., and Anderson, J.B., 2009, Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: paleoclimatic implications, Marine Micropaleontology, v. 73, p. 135-147.. Majewski, W., and Anderson, J.B., 2009, Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: paleoclimatic implications, Marine Micropaleontology, v. 73, p. 135-147.. Majewski, W., Wellner, J.S., Szczucinski, W., and Anderson, J.B., 2012, Holocene oceanographic and glacial changes recorded in Maxwell Bay, West Antarctica, Marine Geology, v. 328, p. 67-79.
