On the relationship between ice volume and sea level over the last glacial cycle

AbstractA widely used method for investigating palaeotemperatures is to analyze local proxy records (e.g. ice cores or deep-sea sediment cores). The interpretation of these records is often not straightforward, and global or hemispheric means cannot be deduced from local estimates because of large spatial variability. Using a different approach, temperature changes over the last glacial cycle can be estimated from sea-level observations by applying an inverse method to an ice-sheet model. In order to understand the underlying physical mechanisms, we used a 1-D ice-sheet model and a 3-D coupled thermodynamic ice-sheet–ice-shelf–bedrock model to investigate the importance of several physical processes for the inverse temperature reconstructions. Results show that (i) temperature reconstructions are sensitive to the employed formulation of mass balance, (ii) excluding thermodynamics in the ice sheet leads to a smaller temperature amplitude in the reconstruction and (iii) hysteresis in the non-linear relation between sea level and temperature occurs as a consequence of ice redistribution in the process of merging and separation of ice sheets. The ice redistribution does not occur if the geometry does not support the formation of a relatively flat dome, which tends to be preserved in warming conditions.

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Ice sheets and sea level of the Last Glacial Maximum

Quaternary Science Reviews ◽

10.1016/s0277-3791(01)00118-4 ◽

2002 ◽

Vol 21 (1-3) ◽

pp. 1-7 ◽

Cited By ~ 337

Author(s):

Peter U. Clark ◽

Alan C. Mix

Keyword(s):

Sea Level ◽

Last Glacial Maximum ◽

Ice Sheets ◽

Glacial Maximum ◽

Last Glacial ◽

The Last Glacial Maximum ◽

The Last Glacial ◽

And Sea Level

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Antarctic ice volume for the last 740 ka calculated with a simple ice sheet model

Antarctic Science ◽

10.1017/s0954102005002683 ◽

2005 ◽

Vol 17 (2) ◽

pp. 281-287 ◽

Cited By ~ 6

Author(s):

J. OERLEMANS

Keyword(s):

Sea Level ◽

Deep Sea ◽

Relative Phase ◽

Ice Sheet ◽

Ice Cores ◽

Temperature History ◽

Glacial Cycle ◽

Ice Volume ◽

The Antarctic ◽

And Sea Level

Fluctuations in the volume of the Antarctic ice sheet for the last 740 ka are calculated by forcing a simple ice sheet model with a sea-level history (from a composite deep sea δ18O record) and a temperature history (from the Dome C deuterium record). Antarctic ice volume reaches maximum values of about 30 × 1015 m3, 3 to 8 ka after glacial maxima [defined as maximum values of the deep sea δ18O record]. Minimum values of ice volume reached in the course of interglacial periods are about 26 × 1015 m3. Most of the time the temperature forcing (larger accumulation) and sea-level forcing (grounding-line retreat) tend to have competing effects. However, towards the end of a glacial cycle, when temperature rises and sea-level is still relatively low, the ice volume reaches a peak. The peak value is very sensitive to the relative phase of the sea-level forcing with respect to the temperature forcing. This is further studied by looking at the response of the model to purely periodic forcings with different relative phase. The large sensitivity of ice sheet size to the phase of the forcings may have some implications for dating of deep ice cores. Care has to be taken by using anchor points from the deep sea record.

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Dependence of late glacial sea-level predictions on 3D Earth structure

10.5194/egusphere-egu2020-7699 ◽

2020 ◽

Author(s):

Meike Bagge ◽

Volker Klemann ◽

Bernhard Steinberger ◽

Milena Latinovic ◽

Maik Thomas

Keyword(s):

Solid Earth ◽

Sea Level ◽

Seismic Tomography ◽

Earth Structure ◽

Glacial Cycle ◽

Relative Sea Level ◽

Last Glacial ◽

Earth Structures ◽

3D Earth Structure ◽

The Last Glacial

<p><span>Glacial isostatic adjustment is dominated by Earth rheology resulting in a variability of relative sea-level (RSL) predictions of more than 100 meters during the last glacial cycle. Seismic tomography models reveal significant lateral variations in seismic wavespeed, most likely corresponding to variations in temperature and hence viscosity. Therefore, the replacement of 1D Earth structures by a 3D Earth structure is an essential part of recent research to reveal the impact of lateral viscosity contrasts and to achieve a more consistent view on solid-Earth dynamics. Here, we apply the VIscoelastic Lithosphere and MAntle model VILMA to predict RSL during the last deglaciation. We create an ensemble of geodynamically constrained 3D Earth structures which is based on seismic tomography models while considering a range of conversion factors to transfer seismic velocity variations into viscosity variations. For a number of globally distributed sites, we discuss the resulting variability in RSL predictions, compare this with regionally optimized 1D Earth structures, and validate the model results with relative sea-level data (sea-level indicators). This study is part of the German Climate Modeling initiative PalMod aiming the modeling of the last glacial cycle under consideration of a coupled Earth system model, i.e. including feedbacks between ice-sheets and the solid Earth.</span></p>

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