There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

Scherer, Reed P.

doi:10.1017/s0022143000016671

Cited by 10 publications

(1 citation statement)

References 26 publications

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“…is consistent with melting of the WAIS (Scherer, 1993;Flores and Sierro, 2007). A decrease in the δ 18 O signature of benthic fauna for the same interval (Fig.…”

Section: Global Records Of Climate and Sea-level Change During The Pliocene-pleistocenesupporting

confidence: 77%

Reconstructing Neogene Climate and Glacial History of Southern McMurdo Sound, Antarctica

Galbraith¹

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<p>Understanding the glacial changes that have occurred in southern McMurdo Sound throughout the Neogene makes an important contribution to reconstructing Antarctic ice volume changes during past periods of climatic warmth, and provides insight into future possible response of the ice sheet. Fossiliferous glacimarine deposits previously identified throughout McMurdo Sound have provided inferences on past changes in ice volume and the implications for global sea level. This study investigates new stratigraphic sections comprising fossiliferous glacimarine sediments from two locations on the flanks of Mount Discovery and one on Brown Peninsula at ~150m above present day sea-level. The aim of this thesis is to undertake a sedimentological, facies and glacimarine sequence stratigraphic analysis together with a quantitative assessment of the constituent micro and macrofossils in order to determine depositional processes, changes in environment and implications for glacial variability in the southern McMurdo Sound. Up to four distinct sedimentary cycles are evident in the Mt Discovery sections with each cycle consisting of: 1. A basal glacial surface of erosion (GSE) or its correlative conformity (CC) seaward of the grounding line, displaying an abrupt transition from a more distal facies to a more proximal facies. 2. A sharp-based massive diamictite displaying physical intermixing of subjacent lithologies, intra formational clasts, soft sediment deformation features, clast rotation features, and a lack of bioturbation, interpreted as subglacial, or in very close proximity to a marine grounding line. In some cases stratified diamictites overly correlative conformities displaying clast alignment, graded beds, and weak decimeter scale parallel bedding in the matrix, interpreted as grounding-line proximal sediment gravity flows or rain-out from ice melt. 3. In some cases, the diamictite passes gradationally-upwards or is sharply overlain by a conglomerate representing appearance of glacimarine fluvio-deltaic deposition or debris flows as the glacier grounding line begins to retreat. 4. Conglomerates are overlain, often sharply, by hemipelagic laminated or massive mudstone and represent the most ice distal and marine part of the sequence at the interglacial minima. 5. A proglacial facies succession is sometimes preserved below the GSE or correlative conformity marking the top of the sequence and usually consists of a transition from mudstone facies into grounding zone proximal conglomerates during re-advance of the grounding line. Lithofacies analysis supported by sediment grainsize, the results of a foraminiferal census and macrofaunal identifications conducted on each facies imply deposition on the continental shelf in depths of up to 400 m, during oscillations in the proximity of a marine grounding line. Radiocarbon dating of constituent macrofauna (barnacle plates) reported only background ¹⁴C implying an age of deposition older than the Last Glacial Maximum. The present day elevation of the site and a model developed here using glacio-iostatic loading and unloading implies that the Mt Discovery sites have been above sea-level for approximately the last ~2.7Ma. Given their inferred association with Scallop Hill Formation and faunal similarity to sequences in the nearby ANDRILL drill cores, a Pliocene age is considered most likely. This finding is consistent with previous investigations that indicate a dynamic, sub-polar marine-terminating ice sheet margin in Southern McMurdo Sound during the Pliocene, with periods of open ice shelf free conditions potentially associated with more frequent regional collapse and retreat events of a marine-based ice sheet in the Ross Sea embayment.</p>

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“…is consistent with melting of the WAIS (Scherer, 1993;Flores and Sierro, 2007). A decrease in the δ 18 O signature of benthic fauna for the same interval (Fig.…”

Section: Global Records Of Climate and Sea-level Change During The Pliocene-pleistocenesupporting

confidence: 77%

Reconstructing Neogene Climate and Glacial History of Southern McMurdo Sound, Antarctica

Galbraith¹

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The contribution to future flood risk in the Severn Estuary from extreme sea level rise due to ice sheet mass loss

Quinn

Bates

Siddall

2013

J. Geophys. Res. Oceans

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[1] In this paper, we assess the risk of future coastal flooding in the Severn Estuary, examining the contribution from low probability extreme sea level rise scenarios resulting from the possibility of increased rates of ice sheet mass loss in the coming century. A simple asymmetric probability distribution is constructed to include sea level rise scenarios of up to 1.9 m by 2100, based on recent assessments of future sea level rise in the UK. A regular sampling procedure, sampling every 1 mm, is used to increase the boundary water levels associated with a current 1:200 year event to force a two-dimensional hydrodynamic model of coastal inundation to examine the influence of sea level rise on inundation of the Somerset Levels region. From the resulting ensemble of predictions an estimation of risk (conditioned upon the hazard and the probability of occurrence) by 2100 is established. The results indicate that although the likelihood of extreme sea level rise due to rapid ice sheet mass loss is low, the resulting hazard can be large, resulting in a significant (29.7%) increase to the projected risk. These findings clearly demonstrate that uncertainty in future sea level rise, mostly associated with the rate of ice sheet mass loss, is a vital component of coastal flood risk, and therefore, needs to be accounted for by decision makers when considering mitigation policies related to coastal flooding.Citation: Quinn, N., P. D. Bates, and M. Siddall (2013), The contribution to future flood risk in the Severn Estuary from extreme sea level rise due to ice sheet mass loss,

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The Antarctic palaeo record and its role in improving predictions of future Antarctic Ice Sheet change

Bentley

2009

J Quaternary Science

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This paper reviews the ways in which the palaeo record of Antarctic Ice Sheet change can be used to improve understanding of contemporary ice sheet behaviour, and thus enhance predictions of future sea‐level change. The main areas where the palaeo ice sheet record can contribute are understanding long‐term ice sheet trajectory; providing data against which ice sheet models can be tested; to identify and understand the range and types of natural ice sheet behaviour; to balance the global water budget; to correct contemporary glaciological measurements of mass change; and to understand the relationship between polar ecosystems and the ice sheet. I review each in turn and argue that research priorities include understanding past West Antarctic Ice Sheet collapse and its timing; a focus on the palaeo record of rapid retreat events and how these unfolded in the geological past; improving the number and range of ice sheet reconstructions, particularly through the Holocene; continuing to investigate the potential for using sediments and landforms to parameterise basal conditions in ice sheet models; and understanding past East Antarctic Ice Sheet dynamics, particularly the evidence for partial deglaciation. Copyright © 2009 John Wiley & Sons, Ltd.

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There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

Cited by 10 publications

References 26 publications

Reconstructing Neogene Climate and Glacial History of Southern McMurdo Sound, Antarctica

Reconstructing Neogene Climate and Glacial History of Southern McMurdo Sound, Antarctica

The contribution to future flood risk in the Severn Estuary from extreme sea level rise due to ice sheet mass loss

The Antarctic palaeo record and its role in improving predictions of future Antarctic Ice Sheet change

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