A Comparison of Deep Antarctic Ice Cores and Their Implications for Climate Between 65,000 and 15,000 Years Ago

Jouzel, Jean; Raisbeck, G. M.; Benoist, Jean-Pierre; Yiou, F.; Lorius, C.; Raynaud, Dominique; Petit, J. R.; Barkov, N. I.; Korotkevitch, Y. S.; Kotlyakov, V. M.

doi:10.1016/0033-5894(89)90003-3

Cited by 139 publications

(59 citation statements)

References 47 publications

(43 reference statements)

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“…Pan-Antarctic cosmogenic surface exposure ages from bedrock samples and glacial erratics indicate that ice thicknesses close to the present coast were several hundred meters greater during the LGM than at present, and tapered inland (SI Appendix, Table S1), in agreement with inferences from ice cores (18). This terrestrial record constrains the vertical dimensions of the former ice sheet, whereas marine geologic interpretations from swath bathymetric and seismic surveys allow the lateral extent of the ice sheet to be reconstructed (19,20).…”

Section: Resultssupporting

confidence: 72%

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

Golledge

Fogwill

Mackintosh

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

135

143

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Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments—a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.

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Section: Resultssupporting

confidence: 72%

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

Golledge

Fogwill

Mackintosh

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

135

143

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“…Results from these cores5 confirmed m y of the paleoctimate inferences made from glacial-geologic data, including the generally lower accumulation rates during isotope stage 2 (Jouzel et al, 1989). These cores, however, are from w d inland on the polar plateau, and relate only indirectly to pdeodimate in coastal regions.…”

Section: 1 Introductionsupporting

confidence: 66%

Beryllium-10 in the Taylor Dome ice core: Applications to Antarctic glaciology and paleoclimatology

Steig¹

1996

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This is an authorized facsimile, made from the miaollm master copy of the original dissertation or master thesis published by UMI. from other deep ice cores, several giaaologid issues need to be addressed.In particular, accumulation data are necessary as input for numerical iceflow-models, for determining the flux of chemical constituents from measured concentrations, and for caicuIation of the offset in age between ice and trapped air in the core.The analysis of cosmogenic beryllium-10 provides a geochemical method for constraining the accumdation-rate history at Taylor Dome.High-resolution measurements were made in shallow firn cores and snow pits to determine the relationship among beryllium-10 concentrations, wet and dry deposition mechanisms, and snow-accumulation rates.Comparison between theoretical and measured variations in deposition over the last 75 years constrains the relationship between beryllium-10 deposition and global average production rates.

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“…The surface of the major part of the East Antarctic Plateau ice sheet may have been about 100 m lower in the last glacial than at present (Jouzel et al, 1989;Pattyn, 1999;Ritz et al, 2001). In contrast, the surface elevation at the margins of the plateau may have been hundreds of meters higher (Näslund et al, 2000;Hättestrand and Johansen, 2005).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 90%

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

et al. 2014

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Abstract. We use a full-Stokes thermo-mechanically coupled ice-flow model to study the dynamics of the glacier inside Scharffenbergbotnen valley, Dronning Maud Land, Antarctica. The domain encompasses a high accumulation rate region and, downstream, a sublimation-dominated bare ice ablation area. The ablation ice area is notable for having old ice at its surface since the vertical velocity is upwards, and horizontal velocities are almost stagnant there. We compare the model simulation with field observations of velocities and the age distribution of the surface ice. No satisfactory match using an isotropic flow law could be found because of too high vertical velocities and much too high horizontal ones in simulations despite varying enhancement factor, geothermal heat flux and surface temperatures over large ranges. However, the existence of a pronounced ice fabric may explain the observed present-day surface velocity and mass balance distribution in the inner Scharffenbergbotnen blue ice area. Near absence of data on the temporal evolution of Scharffenbergbotnen since the Late Glacial Maximum necessitates exploration of the impact of anisotropy using prescribed ice fabrics: isotropic, single maximum, and linear variation with depth, in both two-dimensional and threedimensional flow models. The realistic velocity field simulated with a noncollinear orthotropic flow law, however, produced surface ages in significant disagreement with the few reliable age measurements and suggests that the age field is not in a steady state and that the present distribution is a result of a flow reorganization at about 15 000 yr BP. In order to fully understand the surface age distribution, a transient simulation starting from the Late Glacial Maximum including the correct initial conditions for geometry, age, fabric and temperature distribution would be needed. This is the first time that the importance of anisotropy has been demonstrated in the ice dynamics of a blue ice area and demonstrates the need to understand ice flow in order to better interpret archives of ancient ice for paleoclimate research.

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A Comparison of Deep Antarctic Ice Cores and Their Implications for Climate Between 65,000 and 15,000 Years Ago

Cited by 139 publications

References 47 publications

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

Beryllium-10 in the Taylor Dome ice core: Applications to Antarctic glaciology and paleoclimatology

Influence of anisotropy on velocity and age distribution at Scharffenbergbotnen blue ice area

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