Interglacial Climates and Antarctic Ice Surges

1972 ◽  
Vol 2 (3) ◽  
pp. 401-408 ◽  
Author(s):  
John T. Hollin
Keyword(s):  
Gulf Of Mexico ◽  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Washington Dc ◽  
Ice Ages ◽  
Last Interglacial ◽  
Antarctic Ice Sheet ◽  
The Past ◽  
Pollen Diagrams

Wilson's theory of ice ages implies that the present interglacial will end with, or at least be interrupted by, an Antarctic ice sheet “surge”. Such surges in the past would have caused distinctive rises of sea level: by 10–30 m, in 100 yr or much less, and precisely at the break of climate at the end of each interglacial. Lithostratigraphic, pollen-analytic and radiometric evidence hinting at such a rise (to 17 m?) late in the last interglacial (at about 95,000 BP?) is found in the Spencer's Point formation in Bermuda, the Ladson and Canepatch formations in S. Carolina, the Norfolk formation in Virginia, and above the Walker interglacial swamp in Washington, DC. The strongest evidence that could be found against this rise would be pollen diagrams up toward 17 m which showed continuously freshwater conditions late in the interglacial. Features that might be explained by a surge occur in the Camp Century ice core, in Atlantic, Caribbean and Gulf of Mexico marine cores, and in the Orgnac stalagmite.

scholarly journals Limited Retreat of the Wilkes Basin Ice Sheet during the Last Interglacial.

2020 ◽  
Author(s):  
Johannes Sutter ◽  
Olaf Eisen ◽  
Martin Werner ◽  
Klaus Grosfeld ◽  
Thomas Kleiner ◽  
...  
Keyword(s):  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Last Interglacial ◽  
Antarctic Ice Sheet ◽  
Future Global Warming ◽  
Grounding Line ◽  
Ice Core Record ◽  
East Antarctic Ice Sheet

<p>The response of the marine sectors of the East Antarctic Ice Sheet to future global warming represents a major source of uncertainty in sea level projections. If greenhouse gas emissions continue unbridled, ice loss in these areas may contribute up to several meters to long-term global sea level rise. In East Antarctica, thinning of the ice cover of the George V and Sabrina Coast is currently taking place, and its destabilization in past warm climate periods has been implied. The extent of such past interglacial retreat episodes cannot yet be quantitatively derived from paleo proxy records alone. Ice sheet modelling constrained by paleo observations is therefore critical to assess the stability of the East Antarctic Ice Sheet during warmer climates. We propose that a runaway retreat during the Last Interglacial of the George V Coast grounding line into the Wilkes Subglacial Basin would either leave a clear imprint on the water isotope composition in the neighbouring Talos Dome ice-core record or prohibit the preservation of an ice core record from the Last Interglacial alltogether. We test this hypothesis using a dynamic ice sheet model and infer that the marine Wilkes Basin ice sheet remained stable throughout the Last Interglacial (130,000-120,000 years ago). Our analysis provides the first constraint on Last Interglacial East Antarctic grounding line stability by benchmarking ice sheet model simulations with ice core records. Our findings also imply that ambitious mitigation efforts keeping global temperature rise in check could safeguard this region from irreversible ice loss in the long term.</p>

scholarly journals Greenland ice sheet contribution to sea level rise during the last interglacial period: a modelling study driven and constrained by ice core data

2013 ◽  
Vol 9 (1) ◽  
pp. 353-366 ◽  
Author(s):  
A. Quiquet ◽  
C. Ritz ◽  
H. J. Punge ◽  
D. Salas y Mélia
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Intergovernmental Panel ◽  
Orbital Configuration ◽  
Global Sea Level

Abstract. As pointed out by the forth assessment report of the Intergovernmental Panel on Climate Change, IPCC-AR4 (Meehl et al., 2007), the contribution of the two major ice sheets, Antarctica and Greenland, to global sea level rise, is a subject of key importance for the scientific community. By the end of the next century, a 3–5 °C warming is expected in Greenland. Similar temperatures in this region were reached during the last interglacial (LIG) period, 130–115 ka BP, due to a change in orbital configuration rather than to an anthropogenic forcing. Ice core evidence suggests that the Greenland ice sheet (GIS) survived this warm period, but great uncertainties remain about the total Greenland ice reduction during the LIG. Here we perform long-term simulations of the GIS using an improved ice sheet model. Both the methodologies chosen to reconstruct palaeoclimate and to calibrate the model are strongly based on proxy data. We suggest a relatively low contribution to LIG sea level rise from Greenland melting, ranging from 0.7 to 1.5 m of sea level equivalent, contrasting with previous studies. Our results suggest an important contribution of the Antarctic ice sheet to the LIG highstand.

Ice-sheet surges and the geological record

1969 ◽  
Vol 6 (4) ◽  
pp. 903-910 ◽  
Author(s):  
John T. Hollin
Keyword(s):  
United States ◽  
Sea Level ◽  
Ice Sheet ◽  
The United States ◽  
Tectonic Activity ◽  
Ice Ages ◽  
Antarctic Ice Sheet ◽  
Geological Record ◽  
Glacial Time ◽  
The Antarctic

If they had occurred, ice-sheet surges would have caused sea-level rises of up to 50 m from Gondwanaland and say 20 m from Antarctica. The rises would have taken 100 years or much less, and the sub sequent falls would have taken 50 000 years or so, as the ice built up again. Such rises may explain the extensive (hundreds of miles ?) and sharp (submergence time 4 years ?) coal – marine shale contacts in the Carboniferous cyclothems. The chief rival explanation for these contacts is sudden subsidence. Tests should show (1) if such contacts are better correlated with periods of glaciation or with areas of tectonic activity, (2) how extensive the contacts really are, (3) if there is any evidence of erosion during sea-level falls, (4) if the amplitudes and periods of the cycles fit surges or subsidence, (5) how fast the submergences were, and (6) if any coolings began at the contacts. Wilson suggests that in the Pleistocene the surge coolings were sufficient to trigger the northern ice ages. If so, interglacial pollen profiles should show rapid but temporary marine transgressions beginning at the break of climate. Evidence suggesting such transgressions occurs in England and the United States, but is still insufficient to disprove explanations such as local downwarping. There is no evidence yet for surges in Wisconsin or Post-glacial time. There is some evidence that the Antarctic Ice Sheet is currently building up, but this could be a response to a Post-glacial accumulation increase rather than the prelude to a surge.

scholarly journals Climate dependent contrast in surface mass balance in East Antarctica over the past 216 kyr

2015 ◽  
Vol 11 (1) ◽  
pp. 377-405 ◽  
Author(s):  
F. Parrenin ◽  
S. Fujita ◽  
A. Abe-Ouchi ◽  
K. Kawamura ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Core ◽  
Ice Sheet ◽  
Ice Cores ◽  
Atmospheric Modeling ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Last Interglacial ◽  
Surface Mass ◽  
The Past

Abstract. Documenting past changes in the East Antarctic surface mass balance is important to improve ice core chronologies and to constrain the ice sheet contribution to global mean sea level. Here we reconstruct the past changes in the ratio of surface mass balance (SMB ratio) between the EPICA Dome C (EDC) and Dome Fuji (DF) East Antarctica ice core sites, based on a precise volcanic synchronisation of the two ice cores and on corrections for the vertical thinning of layers. During the past 216 000 years, this SMB ratio, denoted SMBEDC/SMBDF, varied between 0.7 and 1.1, decreasing during cold periods and increasing during warm periods. While past climatic changes have been depicted as homogeneous along the East Antarctic Plateau, our results reveal larger amplitudes of changes in SMB at EDC compared to DF, consistent with previous results showing larger amplitudes of changes in water stable isotopes and estimated surface temperature at EDC compared to DF. Within interglacial periods and during the last glacial inception (Marine Isotope Stages, MIS-5c and MIS-5d), the SMB ratio deviates by up to 30% from what is expected based on differences in water stable isotope records. Moreover, the SMB ratio is constant throughout the late parts of the current and last interglacial periods, despite contrasting isotopic trends. These SMB ratio changes not closely related to isotopic changes are one of the possible causes of the observed gaps between the ice core chronologies at DF and EDC. Such changes in SMB ratio may have been caused by (i) climatic processes related to changes in air mass trajectories and local climate, (ii) glaciological processes associated with relative elevation changes, or (iii) a combination of climatic and glaciological processes, such as the interaction between changes in accumulation and in the position of the domes. Our inferred SMB ratio history has important implications for ice sheet modeling (for which SMB is a boundary condition) or atmospheric modeling (our inferred SMB ratio could serve as a test).

scholarly journals Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

2020 ◽  
Vol 117 (8) ◽  
pp. 3996-4006 ◽  
Author(s):  
Chris S. M. Turney ◽  
Christopher J. Fogwill ◽  
Nicholas R. Golledge ◽  
Nicholas P. McKay ◽  
Erik van Sebille ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Mass Loss ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ocean Warming ◽  
Weddell Sea ◽  
Meridional Overturning Circulation ◽  
Last Interglacial ◽  
Antarctic Ice Sheet

The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further amplify warming.

Inferring the Last Interglacial West Antarctic Ice Sheet from the coupling of an ice core water stable isotope record and an atmospheric general circulation model

2020 ◽  
Author(s):  
Sentia Goursaud ◽  
Louise Sime ◽  
Eric Wolff
Keyword(s):  
General Circulation ◽  
Ice Core ◽  
Ice Sheet ◽  
Circulation Model ◽  
Last Interglacial ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Isotope Record ◽  
Water Stable Isotope

<p><span><span>The Last Interglacial period (</span></span><span><span>130-115 ka BP, </span></span><span><span>hereafter LIG</span></span><span><span>) </span></span><span><span>is often considered as a</span></span> <span><span>prime example to study the effect of </span></span><span><span>warmer-than-present </span></span><span><span>temperatures on polar ice sheets evolution. As the debate mainly focuses on the causes and tip</span></span><span><span>ping</span></span><span><span> point of a potential collapse of the West Antarctic Ice Sheet </span></span><span><span>(hereafter </span></span><span><span>WAIS</span></span><span><span>), </span></span><span><span>few investigations examine the consequences of a wais collapse in terms of atmospheric circulation. </span></span><span><span>However, a knowledge of </span></span><span><span>the state of the atmosphere is necessary to use proxy data recorded in ice cores. </span></span><span><span>By analysing a new ice core drilled in Skytrain ice rise and using climate modeling, t</span></span><span><span>he WACSWAIN (WArm Climate Stability of West Antarctic ice sheet in the last Interglacial) </span></span><span><span>aims to </span></span><span><span>reconstruct WAIS extent during the LIG. Here, we use simulations from the atmospheric general circulation model HadCM3 </span></span> <span><span>with </span></span><span><span>different </span></span><span><span>WAIS configurations. We show that changes in temperature are directly linked to changes in orography through thermodynamic effects, as well as a linear sea ice extent rise over the Pacific Ocean with the WAIS reduction explained by a reversal of meridional winds turning southwards as the WAIS disappears.</span></span> <span><span>At the Skytrain ice rise, we show that not only the isotopic thermometer can be applied, but we also suggest that the water stable isotope record imprinted in the ice core will allow us to quantify the wais reduction.</span></span></p>

Revised Southern Ocean sea surface temperatures over the last 180 ka

2021 ◽  
Author(s):  
David Chandler ◽  
Petra Langebroek
Keyword(s):  
Southern Ocean ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Last Interglacial ◽  
Antarctic Ice Sheet ◽  
Surface Temperatures ◽  
Temperature Reconstructions

<p>Proxy records and climate models suggest that the Last Interglacial (LIG, ~130 to 115 thousand years before present) was characterised by high-latitude air and sea surface temperatures (SSTs) slightly warmer than present, and by mean global sea level a few metres higher. Therefore, the LIG is widely used as an analogue for near-future oceanographic/climatic conditions. Of particular interest is the Antarctic Ice Sheet’s contribution to rapid sea level rise and to Southern Ocean surface freshening, in response to warming. In the Southern Ocean, existing LIG temperature reconstructions suffer from very high variance amongst a low number of individual records. Recent syntheses have focused on the LIG climatic optimum, but conditions during the penultimate glacial are also important for forcing transient climate or Antarctic Ice Sheet simulations. Here we use databases of modern core-top sediments to evaluate the strengths of SST proxies available in the Southern Ocean, and consider their likely sources of bias and variance. By selecting only those paleo-temperature reconstructions which we believe are reliable in this region, we then compile a Southern Ocean SST synthesis covering the penultimate glacial and the LIG. This longer temperature time series can be used as a basis for LIG ice sheet simulations or for climate model development.  </p>

scholarly journals Coupled regional climate–ice-sheet simulation shows limited Greenland ice loss during the Eemian

2013 ◽  
Vol 9 (4) ◽  
pp. 1773-1788 ◽  
Author(s):  
M. M. Helsen ◽  
W. J. van de Berg ◽  
R. S. W. van de Wal ◽  
M. R. van den Broeke ◽  
J. Oerlemans
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Temperature Record ◽  
Last Interglacial ◽  
Central Dome

Abstract. During the last interglacial period (Eemian, 130–115 kyr BP) eustatic global sea level likely peaked at > 6 m above the present-day level, but estimates of the contribution of the Greenland Ice Sheet vary widely. Here we use an asynchronously two-way-coupled regional climate–ice-sheet model, which includes physically realistic feedbacks between the changing ice sheet topography and climate forcing. Our simulation results in a contribution from the Greenland Ice Sheet to the Eemian sea level highstand between 1.2 and 3.5 m, with a most likely value of 2.1 m. Simulated Eemian ice loss in Greenland is dominated by the rapid retreat of the southwestern margin; two-thirds of the ice loss occurred south of 70° N. The southern dome survived the Eemian and remained connected to the central dome. Large-scale ice sheet retreat is prevented in areas with high accumulation. Our results broadly agree with ice-core-inferred elevation changes and marine records, but it does not match with the ice-core-derived temperature record from northern Greenland. During maximum Eemian summertime insolation, Greenland mass loss contributed ~ 0.5 m kyr−1 to sea level rise, 24% of the reconstructed total rate of sea level rise. Next to that, a difference of > 3 m remains between our maximum estimate of the Greenland contribution and the reconstructed minimum value of the global eustatic Eemian highstand. Hence, the Antarctic Ice Sheet must also have contributed significantly to this sea level highstand.

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