Istorvet Ice Cap, East Greenland Late Holocene Radiocarbon Ages Lowell, T.V.; Hall, B.L.; Kelly, M.A.; Bennike, O.; Lusas, A.R.; Honsaker, W.; Smith, C.A.; Levy, L.B.; Travis, S.; Denton, G.H. Lowell, T.V. Hall, B.L. Kelly, M.A. Bennike, O. Lusas, A.R. Honsaker, W. Smith, C.A. Levy, L.B. Travis, S. Denton, G.H. earth science/paleoclimate/others (Istorvet Ice Cap>LATITUDE 70.93>LONGITUDE -22.15) The Greenland Ice Sheet is undergoing dynamic changes that will have global implications if they continue into the future. In this regard, an understanding of how the ice sheet responded to past climate changes affords a baseline for anticipating future behavior. Small, independent ice caps adjacent to the Greenland Ice Sheet (hereinafter called “local ice caps”) are sensitive indicators of the response of Greenland ice-marginal zones to climate change. Therefore, we reconstructed late Holocene ice-marginal fluctuations of the local Istorvet ice cap in east Greenland, using radiocarbon dates of subfossil plants, 10Be dates of surface boulders, and analyses of sediment cores from both threshold and control lakes. During the last termination, the Istorvet ice cap had retreated close to its maximum Holocene position by w11,730 cal yr BP. Radiocarbon dates of subfossil plants exposed by recent recession of the ice margin indicate that the Istorvet cap was smaller than at present from AD 200 to AD 1025. Sediments from a threshold lake show no glacial input until the ice cap advanced to within 365 m of its Holocene maximum position bywAD 1150. Thereafter the ice cap remained at or close to this position until at least AD 1660. The timing of this, the most extensive of the Holocene, expansion is similar to that recorded at some glaciers in the Alps and in southern Alaska. However, in contrast to these other regions, the expansion in east Greenland at AD 1150 appears to have been very close to, if not at, a maximum Holocene value. Comparison of the Istorvet ice-cap fluctuations with Holocene glacier extents in Southern Hemisphere middle-to-high latitude locations on the Antarctic Peninsula and in the Andes and the Southern Alps suggests an out-of-phase relationship. If correct, this pattern supports the hypothesis that a bipolar see-saw of oceanic and/or atmospheric circulation during the Holocene produced asynchronous glacier response at some localities in the two polar hemispheres. STUDY NOTES: Radiocarbon ages from subfossil plants collected on the western side of the Istorvet ice cap, Liverpool Land, East Greenland. These radiocarbon ages represent former plants growing at near the current margin of the ice cap and thus represent the last time the ice cap was the same size or smaller than present. Data include location, field label, dated material, NOSAMS number, d13C, Age, error, start AD, End AD, Relative area, Other Taxa, latitude, longitude, and elevation. Istorvet Site Locations: 70.87 to 71.0°N, 21.17 to 22.28°W, 520 to 835m elev. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Lowell, T.V. Investigator : Hall, B.L. Investigator : Kelly, M.A. Investigator : Bennike, O. Investigator : Lusas, A.R. Investigator : Honsaker, W. Investigator : Smith, C.A. Investigator : Levy, L.B. Investigator : Travis, S. Investigator : Denton, G.H. 2012-08-06 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13181 https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.txt https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.xls https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.txt https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.xls English https://www.ncdc.noaa.gov/paleo/study/13181 https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.txt https://www1.ncdc.noaa.gov/pub/data/paleo/radiocarbon/istorvet2012c14.xls Lowell, Thomas V., Brenda L. Hall, Meredith A. Kelly, Ole Bennike, Amanda R. Lusas, William Honsaker, Colby A. Smith, Laura B. Levy, Scott Travis, and George H. Denton2013Late Holocene expansion of Istorvet ice cap, Liverpool Land, east GreenlandQuaternary Science Reviews63 START YEAR: 1590 cal yr BP * END YEAR: 115 cal yr BP -22.15 70.93 -22.15 70.93