scholarly journals Calibrating Antarctic ice sheet mass loss due to millennial-scale ocean thermal forcing

2021 ◽  
Author(s):  
Gavin Piccione ◽  
Terrence Blackburn ◽  
Slawek Tulaczyk ◽  
Troy Rasbury ◽  
Mathis Hain ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Level ◽  
Late Pleistocene ◽  
Ice Sheet ◽  
Ocean Temperature ◽  
Thermal Forcing ◽  
Antarctic Ice Sheet ◽  
Repeated Heating ◽  
Millennial Scale ◽  
East Antarctic Ice Sheet

Abstract Throughout the Late Pleistocene, millennial-scale cycles in the rate of poleward heat transport resulted in repeated heating and cooling of the Southern Ocean1. Ice sheet models2 suggest that this variation in Southern Ocean temperature can force fluctuations in the mass of the Antarctic ice sheet that transiently impact sea level by up to 15 meters. However, current geologic evidence for Antarctic ice response to this ocean thermal forcing is unable to calibrate these models, leaving large uncertainty in how Antarctica contributes to sea level on millennial timescales. Here we present a >100kyr archive of East Antarctic Ice Sheet response to Late Pleistocene millennial-scale climate cycles recorded by transitions from opal to calcite in subglacial precipitates. 234U-230Th dates for two precipitates define a time series for 32 mineralogic transitions that match Antarctic climate fluctuations, with precipitation of opal during cold periods and calcite during warm periods. Geochemical evidence indicates opal precipitation via cryoconcentration of silica in subglacial water and calcite precipitation from the admixture of meltwater flushed from the ice sheet interior. These freeze-flush cycles represent changes in subglacial hydrologic-connectivity driven by ice sheet thickness response to Southern Ocean temperature oscillations around the Ross Embayment. Changes in Ross Embayment ice mass require high ocean-ice heat exchange2, and would occur only after retreat of the West Antarctic Ice Sheet3 and large portions of the East Antarctic Ice sheet margin4. These results point to high Antarctic ice sheet sensitivity to millennial-scale ocean thermal forcing throughout the Late Pleistocene, and when combined with modeling results2, predict that an Antarctic ice volume of at least 2–5 meters sea level equivalent is vulnerable to millennial-scale climate forcing.

The contribution of the East Antarctic Ice Sheet to future sea level rise

2020 ◽  
Author(s):  
Jim Jordan ◽  
Hilmar Gudmundsson ◽  
Adrian Jenkins ◽  
Chris Stokes ◽  
Stewart Jamieson ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Mean Sea Level ◽  
Potential Contributor ◽  
Global Mean Sea Level ◽  
Global Mean ◽  
East Antarctic Ice Sheet

<p>The East Antarctic Ice Sheet (EAIS) is the single largest potential contributor to future global mean sea level rise, containing a water mass equivalent of 53 m. Recent work has found the overall mass balance of the EAIS to be approximately in equilibrium, albeit with large uncertainties. However, changes in oceanic conditions have the potential to upset this balance. This could happen by both a general warming of the ocean and also by shifts in oceanic conditions allowing warmer water masses to intrude into ice shelf cavities.</p><p>We use the Úa numerical ice-flow model, combined with ocean-melt rates parameterized by the PICO box mode, to predict the future contribution to global-mean sea level of the EAIS. Results are shown for the next 100 years under a range of emission scenarios and oceanic conditions on a region by region basis, as well as for the whole of the EAIS. </p>

Testing the sensitivity of the East Antarctic Ice Sheet to Southern Ocean dynamics: past changes and future implications

2013 ◽  
Vol 29 (1) ◽  
pp. 91-98 ◽  
Author(s):  
CHRISTOPHER J. FOGWILL ◽  
CHRISTIAN S. M. TURNEY ◽  
KATRIN J. MEISSNER ◽  
NICHOLAS R. GOLLEDGE ◽  
PAUL SPENCE ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Ocean Dynamics ◽  
Antarctic Ice Sheet ◽  
East Antarctic Ice Sheet

scholarly journals Short Note: New marine core record of Late Pleistocene glaciation history, Rauer Group, East Antarctica

2009 ◽  
Vol 21 (3) ◽  
pp. 299-300 ◽  
Author(s):  
Sonja Berg ◽  
Bernd Wagner ◽  
Duanne A. White ◽  
Holger Cremer ◽  
Ole Bennike ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Quaternary ◽  
Short Note ◽  
Ice Sheet ◽  
East Antarctica ◽  
Prydz Bay ◽  
Pleistocene Glaciation ◽  
Antarctic Ice Sheet ◽  
Significant Variability ◽  
East Antarctic Ice Sheet

The evolution of the East Antarctic Ice Sheet (EAIS) during the Late Quaternary is poorly known, partly because some regions, such as the Prydz Bay vicinity, indicate significant variability in the glaciation patterns (e.g. Domack et al. 1998, Zwartz et al. 1998, Hodgson et al. 2005).

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.

ISMIP6-based projections of ocean-forced Antarctic ice loss using the Community Ice Sheet Model 

2021 ◽  
Author(s):  
William Lipscomb ◽  
Gunter Leguy ◽  
Nicolas Jourdain ◽  
Xylar Asay-Davis ◽  
Hélène Seroussi ◽  
...  
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Global Climate ◽  
Ice Sheet ◽  
High Sensitivity ◽  
Global Climate Models ◽  
Thermal Forcing ◽  
Antarctic Ice Sheet ◽  
Basal Friction ◽  
West Antarctic

<p>The future retreat rate for marine-based regions of the Antarctic Ice Sheet is one of the largest uncertainties in sea-level projections. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) aims to improve projections and quantify uncertainties by running an ensemble of ice sheet models with forcing derived from global climate models. Here, the Community Ice Sheet Model (CISM) is used to run ISMIP6-based projections of ocean-forced Antarctic Ice Sheet evolution. Using several combinations of sub-ice-shelf melt schemes, CISM is spun up to steady state over many millennia. During the spin-up, basal-friction and thermal-forcing parameters are adjusted to optimize agreement with the observed ice thickness. The model is then run forward to year 2500, applying ocean thermal forcing anomalies from six climate models. In all simulations, ocean warming triggers long-term retreat of the West Antarctic Ice Sheet, especially in the Filchner-Ronne and Ross sectors. The ocean-forced sea-level rise in 2500 varies from about 150 mm to 1300 mm, depending on the melt scheme and ocean forcing applied. Further experiments show relatively high sensitivity to the basal friction law, and moderate sensitivity to grid resolution and the prescribed collapse of small ice shelves. The Amundsen sector exhibits threshold behavior, with modest retreat under many parameter settings, but complete collapse under some combinations of low basal friction and high thermal-forcing anomalies. Large uncertainties remain, as a result of parameterized sub-shelf melt rates, simplified treatments of calving and basal friction, and the lack of ice–ocean coupling.</p>

scholarly journals A new sea-level record for the Neogene/Quaternary boundary reveals transition to a more stable East Antarctic Ice Sheet

2020 ◽  
Vol 117 (49) ◽  
pp. 30980-30987
Author(s):  
Kim A. Jakob ◽  
Paul A. Wilson ◽  
Jörg Pross ◽  
Thomas H. G. Ezard ◽  
Jens Fiebig ◽  
...  
Keyword(s):  
Sea Level ◽  
Northern Hemisphere ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Deep Ocean ◽  
Antarctic Ice Sheet ◽  
Sea Levels ◽  
Ice Volume ◽  
Warming World ◽  
East Antarctic Ice Sheet

Sea-level rise resulting from the instability of polar continental ice sheets represents a major socioeconomic hazard arising from anthropogenic warming, but the response of the largest component of Earth’s cryosphere, the East Antarctic Ice Sheet (EAIS), to global warming is poorly understood. Here we present a detailed record of North Atlantic deep-ocean temperature, global sea-level, and ice-volume change for ∼2.75 to 2.4 Ma ago, when atmospheric partial pressure of carbon dioxide (pCO2) ranged from present-day (>400 parts per million volume, ppmv) to preindustrial (<280 ppmv) values. Our data reveal clear glacial–interglacial cycles in global ice volume and sea level largely driven by the growth and decay of ice sheets in the Northern Hemisphere. Yet, sea-level values during Marine Isotope Stage (MIS) 101 (∼2.55 Ma) also signal substantial melting of the EAIS, and peak sea levels during MIS G7 (∼2.75 Ma) and, perhaps, MIS G1 (∼2.63 Ma) are also suggestive of EAIS instability. During the succeeding glacial–interglacial cycles (MIS 100 to 95), sea levels were distinctly lower than before, strongly suggesting a link between greater stability of the EAIS and increased land-ice volumes in the Northern Hemisphere. We propose that lower sea levels driven by ice-sheet growth in the Northern Hemisphere decreased EAIS susceptibility to ocean melting. Our findings have implications for future EAIS vulnerability to a rapidly warming world.

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