The sensitivity of Northern Hemisphere ice sheets to atmospheric forcing during the last glacial cycle using PMIP3 models

ABSTRACTThe evolution of Northern Hemisphere ice sheets through the last glacial cycle is simulated with the glacial index method by using the climate forcing from one General Circulation Model, COSMOS. By comparing the simulated results to geological reconstructions, we first show that the modelled climate is capable of capturing the main features of the ice-sheet evolution. However, large deviations exist, likely due to the absence of nonlinear interactions between ice sheet and other climate components. The model uncertainties of the climate forcing are examined using the output from nine climate models from the Paleoclimate Modelling Intercomparison Project Phase III. The results show a large variability in simulated ice sheets between the different models. We find that the ice-sheet extent pattern resembles summer surface air temperature pattern at the Last Glacial Maximum, confirming the dominant role of surface ablation process for high-latitude Northern Hemisphere ice sheets. This study shows the importance of the upper boundary condition for ice-sheet modelling, and implies that careful constraints on climate output is essential for simulating realistic glacial Northern Hemisphere ice sheets.

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Sensitivity of atmospheric forcing on Northern Hemisphere ice sheets during the last glacial-interglacial cycle using output from PMIP3

10.5194/cp-2017-105 ◽

2017 ◽

Cited By ~ 3

Author(s):

Lu Niu ◽

Gerrit Lohmann ◽

Sebastian Hinck ◽

Evan J. Gowan

Keyword(s):

Northern Hemisphere ◽

Air Temperature ◽

Ice Sheets ◽

Ice Sheet ◽

Surface Air Temperature ◽

Phase Iii ◽

Temperature Pattern ◽

Atmospheric Forcing ◽

Last Glacial ◽

The Last Glacial

Abstract. We use the three-dimensional Parallel Ice Sheet Model (PISM) to simulate Northern Hemisphere ice sheets evolution through the last glacial-interglacial cycle. The simulation is driven by the NGRIP δ18O index combined with climate forcing at two time slices, the Last Glacial Maximum (LGM) and present day (PD). In order to investigate the sensitivity of the ice sheets to the atmospheric forcing, atmospheric output from nine climate models from the Paleoclimate Modeling Intercomparison Project Phase III (PMIP3) are used to force the ice sheet model with the same set-up. The results show large diversity in simulated ice sheets between different models. By comparing the atmospheric forcing, we found that summer surface air temperature pattern resembles the ice sheet extent pattern at the LGM, which shows great sensitivity to summer surface air temperature. This implies that careful constrains on climate output is essential for simulating reliable glacial-interglacial Northern Hemisphere ice sheets. The ablation process is of vital importance for high-latitude Northern Hemisphere ice sheets. Besides, the absent nonlinear interactions between ice sheet and atmosphere and ocean, which have different signals regionally, also contribute to the mismatches between simulated ice sheets and geological evidences. Hence, we highlight the needs for coupling an ice sheet model to GCM to take into account these missing processes.

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Investigating the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle

Climate of the Past ◽

10.5194/cp-5-329-2009 ◽

2009 ◽

Vol 5 (3) ◽

pp. 329-345 ◽

Cited By ~ 62

Author(s):

S. Bonelli ◽

S. Charbit ◽

M. Kageyama ◽

M.-N. Woillez ◽

G. Ramstein ◽

...

Keyword(s):

Northern Hemisphere ◽

Climate Model ◽

Ice Sheets ◽

Ice Sheet ◽

Co2 Concentration ◽

Atmospheric Co2 ◽

Glacial Cycle ◽

Last Glacial ◽

Atmospheric Co2 Concentration ◽

The Last Glacial

Abstract. A 2.5-dimensional climate model of intermediate complexity, CLIMBER-2, fully coupled with the GREMLINS 3-D thermo-mechanical ice sheet model is used to simulate the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle and to investigate the ice sheets responses to both insolation and atmospheric CO2 concentration. This model reproduces the main phases of advance and retreat of Northern Hemisphere ice sheets during the last glacial cycle, although the amplitude of these variations is less pronounced than those based on sea level reconstructions. At the last glacial maximum, the simulated ice volume is 52.5×1015 m3 and the spatial distribution of both the American and Eurasian ice complexes is in reasonable agreement with observations, with the exception of the marine parts of these former ice sheets. A set of sensitivity studies has also been performed to assess the sensitivity of the Northern Hemisphere ice sheets to both insolation and atmospheric CO2. Our results suggest that the decrease of summer insolation is the main factor responsible for the early build up of the North American ice sheet around 120 kyr BP, in agreement with benthic foraminifera δ18O signals. In contrast, low insolation and low atmospheric CO2 concentration are both necessary to trigger a long-lasting glaciation over Eurasia.

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Influence of ablation-related processes in the built-up of simulated Northern Hemisphere ice sheets during the last glacial cycle

The Cryosphere Discussions ◽

10.5194/tcd-6-4897-2012 ◽

2012 ◽

Vol 6 (6) ◽

pp. 4897-4938 ◽

Cited By ~ 1

Author(s):

S. Charbit ◽

C. Dumas ◽

M. Kageyama ◽

D. M. Roche ◽

C. Ritz

Keyword(s):

Northern Hemisphere ◽

Ice Sheets ◽

Ice Sheet ◽

Glacial Cycle ◽

Satisfactory Description ◽

Last Glacial ◽

Transient Simulations ◽

Main Driver ◽

The Impact ◽

The Last Glacial

Abstract. Since the original formulation of the positive-degree-day (PDD) method, different PDD calibrations have been proposed in the literature in response to the increasing number of observations. Although these formulations provide a satisfactory description of the present-day Greenland geometry, they have not all been tested for paleo ice sheets. Using the climate-ice sheet model CLIMBER-GRISLI coupled with different PDD models, we evaluate how the parameterization of the ablation may affect the evolution of Northern Hemisphere ice sheets in the transient simulations of the last glacial cycle. Results from fully coupled simulations are compared to time-slice experiments carried out at different key periods of the last glacial period. We find large differences in the simulated ice sheets according to the chosen PDD model. These differences occur as soon as the onset of glaciation, therefore affecting the subsequent evolution of the ice system. To further investigate how the PDD method controls this evolution, special attention is given to the role of each PDD parameter. We show that glacial inception is critically dependent on the representation of the impact of the temperature variability from the daily to the inter-annual time scale, whose effect is modulated by the refreezing scheme. Finally, an additional set of sensitivity experiments has been carried out to assess the relative importance of melt processes with respect to initial ice sheet configuration in the construction and the evolution of past Northern Hemisphere ice sheets. Our analysis reveals that the impacts of the initial ice sheet condition may range from quite negligible to explaining about half of the LGM ice volume depending on the representation of stochastic temperature variations which remain the main driver of the evolution of the ice system.

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Ice-sheet models as tools for palaeoclimatic analysis: the example of the European ice sheet through the last glacial cycle

Annals of Glaciology ◽

10.1017/s0260305500015676 ◽

1995 ◽

Vol 21 ◽

pp. 103-110 ◽

Cited By ~ 10

Author(s):

G. S. Boulton ◽

N. Hulton ◽

M. Vautravers

Keyword(s):

Numerical Model ◽

Ice Sheets ◽

Ice Sheet ◽

Early Holocene ◽

Climate Forcing ◽

Glacial Period ◽

Glacial Cycle ◽

Last Glacial ◽

Sheet Surface ◽

The Last Glacial

A numerical model is used to simulate ice-sheet behaviour in Europe through the last glacial cycle. It is used in two modes: a forward mode, in which the model is driven by a proxy palaeoclimate record and the output compared with a geological reconstruction of ice-sheet fluctuation; and an inverse mode, in which we determine the climate function that would be required to simulate geologically reconstructed ice-sheet fluctuations. From these simulations it is concluded that extra-glacial climates may be poor predictors of ice-sheet surface climates, and that climatic transitions during the glacial period may have been much more rapid and the intensity of warming during the early Holocene much greater than hitherto supposed. Stronger climate forcing is required to drive ice-sheet expansion when sliding occurs at the bed compared with a non-sliding bed. Sliding ice sheets grow more slowly and decay more rapidly than non-sliding ice sheets with the same climate forcing.

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Ice-sheet models as tools for palaeoclimatic analysis: the example of the European ice sheet through the last glacial cycle

Annals of Glaciology ◽

10.3189/s0260305500015676 ◽

1995 ◽

Vol 21 ◽

pp. 103-110

Author(s):

G. S. Boulton ◽

N. Hulton ◽

M. Vautravers

Keyword(s):

Numerical Model ◽

Ice Sheets ◽

Ice Sheet ◽

Early Holocene ◽

Climate Forcing ◽

Glacial Period ◽

Glacial Cycle ◽

Last Glacial ◽

Sheet Surface ◽

The Last Glacial

A numerical model is used to simulate ice-sheet behaviour in Europe through the last glacial cycle. It is used in two modes: a forward mode, in which the model is driven by a proxy palaeoclimate record and the output compared with a geological reconstruction of ice-sheet fluctuation; and an inverse mode, in which we determine the climate function that would be required to simulate geologically reconstructed ice-sheet fluctuations.From these simulations it is concluded that extra-glacial climates may be poor predictors of ice-sheet surface climates, and that climatic transitions during the glacial period may have been much more rapid and the intensity of warming during the early Holocene much greater than hitherto supposed. Stronger climate forcing is required to drive ice-sheet expansion when sliding occurs at the bed compared with a non-sliding bed. Sliding ice sheets grow more slowly and decay more rapidly than non-sliding ice sheets with the same climate forcing.

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Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle

Climate of the Past ◽

10.5194/cp-3-15-2007 ◽

2007 ◽

Vol 3 (1) ◽

pp. 15-37 ◽

Cited By ~ 80

Author(s):

S. Charbit ◽

C. Ritz ◽

G. Philippon ◽

V. Peyaud ◽

M. Kageyama

Keyword(s):

Northern Hemisphere ◽

General Circulation ◽

Ice Sheets ◽

Ice Sheet ◽

Maximum Amplitude ◽

The Other ◽

Climate Forcing ◽

Last Glacial ◽

Ice Volume ◽

The Last Glacial

Abstract. A 3-dimensional thermo-mechanical ice-sheet model is used to simulate the evolution of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle. The ice-sheet model is forced by the results from six different atmospheric general circulation models (AGCMs). The climate evolution over the period under study is reconstructed using two climate equilibrium simulations performed for the Last Glacial Maximum (LGM) and for the present-day periods and an interpolation through time between these snapshots using a glacial index calibrated against the GRIP δ18O record. Since it is driven by the timing of the GRIP signal, the temporal evolution of the ice volume and the ice-covered area is approximately the same from one simulation to the other. However, both ice volume curves and spatial distributions of the ice sheets present some major differences from one AGCM forcing to the other. The origin of these differences, which are most visible in the maximum amplitude of the ice volume, is analyzed in terms of differences in climate forcing. This analysis allows for a partial evaluation of the ability of GCMs to simulate climates consistent with the reconstructions of past ice sheets. Although some models properly reproduce the advance or retreat of ice sheets in some specific areas, none of them is able to reproduce both North American or Eurasian ice complexes in full agreement with observed sea-level variations and geological data. These deviations can be attributed to shortcomings in the climate forcing and in the LGM ice-sheet reconstruction used as a boundary condition for GCM runs, but also to missing processes in the ice-sheet model itself.

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Modeling the marine extent of Northern Hemisphere ice sheets during the last glacial cycle

Annals of Glaciology ◽

10.3189/172756403781815870 ◽

2003 ◽

Vol 37 ◽

pp. 173-180 ◽

Cited By ~ 20

Author(s):

Chris Zweck ◽

Philippe Huybrechts

Keyword(s):

Northern Hemisphere ◽

Water Depth ◽

Three Dimensional ◽

Ice Sheets ◽

Ice Sheet ◽

Glacial Cycle ◽

Last Glacial ◽

History Of ◽

The Last Glacial Maximum ◽

The Last Glacial

AbstractMechanisms that determine time-dependent changes of the marine ice margin in dynamic ice-sheet models are important but poorly understood. Here we derive an empirical formulation for changes in the marine extent when modelling the Northern Hemisphere ice sheets over the last glacial cycle in a three-dimensional thermomechanically coupled ice-sheet model. We assume that the strongest control on changes in marine extent is ice calving, and that the variable most crucial to calving is water depth. The empirical marine-extent relationship is tuned so that the major marine-retreat history of the Laurentide and Eurasian ice sheets is modelled accurately in time and space. We find that this empirical treatment relating marine extent to water depth is sufficient to reproduce the observations, and discuss the implications for the physics of marine margin changes and the dynamics of the Northern Hemisphere ice sheets since the Last Glacial Maximum.

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Investigating the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle

Climate of the Past Discussions ◽

10.5194/cpd-5-1013-2009 ◽

2009 ◽

Vol 5 (2) ◽

pp. 1013-1053 ◽

Cited By ~ 1

Author(s):

S. Bonelli ◽

S. Charbit ◽

M. Kageyama ◽

M.-N. Woillez ◽

G. Ramstein ◽

...

Keyword(s):

Northern Hemisphere ◽

Climate Model ◽

Ice Sheets ◽

Ice Sheet ◽

Co2 Concentration ◽

Atmospheric Co2 ◽

Glacial Cycle ◽

Last Glacial ◽

Atmospheric Co2 Concentration ◽

The Last Glacial

Abstract. A 2.5-dimensional climate model of intermediate complexity fully coupled with a 3-dimensional thermo-mechanical ice sheet model is used to simulate the evolution of major Northern Hemisphere ice sheets during the last glacial-interglacial cycle and to investigate the ice sheets responses to both insolation and atmospheric CO2 concentration. This model reproduces the main phases of advance and retreat of Northern Hemisphere ice sheets during the last glacial cycle, although the amplitude of these variations is less pronounced than those based on sea level reconstructions. At the last glacial maximum, the simulated ice volume is 52.5×1015 m3 and the spatial distribution of both the American and Eurasian ice complexes is in reasonable agreement with observations, with the exception of the marine parts of these former ice sheets. A set of sensitivity studies has also been performed to assess the sensitivity of the Northern Hemisphere ice sheets to both insolation and atmospheric CO2. Our results suggest that the decrease of summer insolation is the main factor responsible for the early build up of the North American ice sheet around 120 kyr BP, in agreement with benthic foraminifera δ18O signals. In contrast, low insolation and low atmospheric CO2 concentration are both necessary to trigger a long-lasting glaciation over Eurasia.

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Numerical reconstructions of the Northern Hemisphere ice sheets through the last glacial-interglacial cycle

Climate of the Past Discussions ◽

10.5194/cpd-2-879-2006 ◽

2006 ◽

Vol 2 (5) ◽

pp. 879-921 ◽

Cited By ~ 2

Author(s):

S. Charbit ◽

C. Ritz ◽

G. Philippon ◽

V. Peyaud ◽

M. Kageyama

Keyword(s):

Northern Hemisphere ◽

General Circulation ◽

Ice Sheets ◽

Ice Sheet ◽

Maximum Amplitude ◽

The Other ◽

Climate Forcing ◽

Last Glacial ◽

Ice Volume ◽

The Last Glacial

Abstract. A 3-dimensional thermo-mechanical ice-sheet model is used to simulate the evolution of the Northern hemisphere ice sheets through the last glacial-interglacial cycle. The ice-sheet model is forced by the results from six different atmospheric general circulation models (AGCMs). Two climate snapshots simulations performed for the last glacial maximum (LGM) and for the present-day periods are interpolated through time using a glacial index calibrated against the GRIP δ18O record to reconstruct the climate evolution over the period under study. Since it is driven by the timing of the GRIP signal, the temporal evolution of the ice volume and the ice-covered area is approximately the same from one simulation to the other. However, both ice volume curves and spatial distributions of the ice sheets present some major differences from one AGCM to the other. The origin of these differences, which are most visible in the maximum amplitude of the ice volume, is analyzed in terms of differences in climate forcing. The analysis of the results allows an evaluation of the ability of GCMs to simulate climates consistent with the reconstructions of past ice sheets to be evaluated. Although some models properly reproduce the advance or retreat of ice sheets in some specific areas, none of them is able to reproduce both North American or Eurasian ice complexes in full agreement with observed sea-level variations and geological data. These deviations can be attributed to shortcomings in the climate forcing and in the LGM ice-sheet reconstruction used as a boundary condition for GCM runs, but also to missing processes in the ice-sheet model itself.

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Influence of ablation-related processes in the build-up of simulated Northern Hemisphere ice sheets during the last glacial cycle

The Cryosphere ◽

10.5194/tc-7-681-2013 ◽

2013 ◽

Vol 7 (2) ◽

pp. 681-698 ◽

Cited By ~ 23

Author(s):

S. Charbit ◽

C. Dumas ◽

M. Kageyama ◽

D. M. Roche ◽

C. Ritz

Keyword(s):

Northern Hemisphere ◽

Climate Models ◽

Ice Sheets ◽

Ice Sheet ◽

Glacial Cycle ◽

Satisfactory Description ◽

Last Glacial ◽

Transient Simulations ◽

The Impact ◽

The Last Glacial

Abstract. Since the original formulation of the positive-degree-day (PDD) method, different PDD calibrations have been proposed in the literature in response to the increasing number of observations. Although these formulations generally provide a satisfactory description of the present-day Greenland geometry, they have not all been tested for paleo ice sheets. Using the climate-ice sheet model CLIMBER-GRISLI coupled with different PDD models, we evaluate how the parameterisation of the ablation may affect the evolution of Northern Hemisphere ice sheets in the transient simulations of the last glacial cycle. Results from fully coupled simulations are compared to time-slice experiments carried out at different key periods of the last glacial period. We find large differences in the simulated ice sheets according to the chosen PDD model. These differences occur as soon as the onset of glaciation, therefore affecting the subsequent evolution of the ice system. To further investigate how the PDD method controls this evolution, special attention is given to the role of each PDD parameter. We show that glacial inception is critically dependent on the representation of the impact of the temperature variability from the daily to the inter-annual time scale, whose effect is modulated by the refreezing scheme. Finally, an additional set of sensitivity experiments has been carried out to assess the relative importance of melt processes with respect to initial ice sheet configuration in the construction and the evolution of past Northern Hemisphere ice sheets. Our analysis reveals that the impacts of the initial ice sheet condition may range from quite negligible to explaining about half of the LGM ice volume depending on the representation of stochastic temperature variations which remain the main driver of the evolution of the ice system. The main findings of this paper underline the need for conducting studies with high resolution climate models coupled to detailed snow models to better constrain the temporal and spatial variations of the PDD parameters. The development of such approaches could improve the calibration of the PDD formulation which is still widely used in climate-ice sheet studies.

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