HR: 14:10h
AN: C13A-03 INVITED    [Abstracts]
TI: Late Holocene Sea-levels, Climate and Ice Sheet Dynamics in West Greenland
AU: * Long, A J
EM: A.J.Long@Durham.ac.uk
AF: Durham University, Science Laboratories South Road, Durham, DH1 3LE, United Kingdom
AU: Woodroffe, S A
EM: S.A.Woodroffe@Durham.ac.uk
AF: Durham University, Science Laboratories South Road, Durham, DH1 3LE, United Kingdom
AU: Bryant, C
EM: Charlotte.Bryant@nercrcl.gla.ac.uk
AF: NERC Radiocarbon Laboratory, Scottish Enterprise Technology Park Rankine Avenue East Kilbride, Glasgow, G75 OQF, United Kingdom
AB: At the end of the Holocene altithermal, c. 5 ka cal. yr BP, the Greenland Ice Sheet (GIS) had retreated 10-30 km inland of its present position. During the subsequent neoglacial, from c. 4 ka cal yr BP onwards, the GIS re-grew, advancing to reach a maximum extent during the "Little Ice Age". This re-growth saw an increase in load on the earth's surface that, throughout West Greenland, was accompanied by a switch from early and mid Holocene relative sea-level (RSL) fall to late Holocene RSL rise. Evidence for this rise includes drowned archaeological sites, submerged freshwater peats and flooded lake basins. Recently collected sediment cores from flooded lake basins in Disko Bugt and Kangerlussuaq (and from elsewhere in West Greenland) define millennial scale trends in mid and late Holocene RSL that reflect increased ice load during the neoglacial. They provide powerful constraints on geophysical models of Holocene ice sheet history. However, such records lack the resolution required to explore the short-term dynamic interactions between the ice sheet and RSL during the last millennia. In this paper we present a high resolution RSL record from Kangerlussuaq from this period. Our approach uses thin, radiocarbon-dated salt marsh deposits that overlie bedrock. We reconstruct RSL change between c. AD 1400 and the present using seventeen radiocarbon dates on terrestrial plant macrofossils, together with an extensive database of fossil and modern diatom assemblages. Our data indicate a long-term rate of RSL rise over this period of c. 1.3 mm yr-1, close to that suggested by recent GPS observations (when corrected for a twentieth century "eustatic" sea-level rise of c. 1.5-2 mm yr-1). We also identify higher frequency variability in our record that may reflect changes in ice load associated with the "Little Ice Age" in West Greenland. High resolution RSL records, such as this, provide a new target for geophysical models of ice sheet mass balance change and a long term context for short term geodetic records of crustal motions and ice sheet dynamics.
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1621 Cryospheric change (0776)
DE: 1630 Impacts of global change (1225)
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Cryosphere [C]
MN: 2007 Fall Meeting