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

Charbit, S.; Ritz, Catherine; Philippon, G.; Peyaud, Vincent; Kageyama, Masa

doi:10.5194/cp-3-15-2007

Cited by 117 publications

(142 citation statements)

References 69 publications

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“…Numerical ice sheet modeling could improve the understanding of this period but most studies focus on the primary inception regions over North America and western Siberia (Marshall and Clarke, 1999;Zweck and Huybrechts, 2005;Calov et al, 2005a;Kubatzki et al, 2006;Charbit et al, 2007;Peyaud et al, 2007). This is probably due to the lack of constraints on timing and extent of ice from data, but also because the steep Scandinavian topography and variable climate are a challenge for the realistic representation of glaciers.…”

Section: Introductionmentioning

confidence: 99%

Warm Nordic Seas delayed glacial inception in Scandinavia

2010

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Abstract.We simulate the last glacial inception, 115 000 years ago, with a three dimensional thermomechanical ice sheet model of the Northern Hemisphere, forced by a comprehensive coupled climate model. High oceanic heat transport into the Nordic Seas prevents large scale ice growth over Scandinavia. Glacial inception in the region starts on the highest mountains in the south when sea surface temperatures in the Nordic Seas are reduced by at least 3 • C.

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Section: Introductionmentioning

confidence: 99%

Warm Nordic Seas delayed glacial inception in Scandinavia

2010

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“…Although the geographical extents of the LGM ice sheets are well constrained, it is still uncertain how the ice sheets arrived at the observed extents (Dyke et al, 2002;Kleman et al, 2010). Modelling efforts of the last glacial cycle reveal different results of the ice-sheet extent at LGM (Tarasov and Peltier, 1997;Charbit et al, 2007;Bonelli et al, 2009). Typically, the models predict too much ice on Alaska or they are unable to capture the increased equatorward extent over eastern North America.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, features associated with ice-sheet dynamics and the atmospheric state remain sources of uncertainty. The uncertainty associated with the atmospheric state was illustrated in Charbit et al (2007), who simulated the evolution of the ice sheets through the last glacial cycle using anomalies of temperature and precipitation computed by six different atmospheric general circulation models (AGCMs). They found that the spatial distributions and shapes of the Northern Hemisphere ice sheets at LGM were sensitive to the employed atmospheric model.…”

Section: Introductionmentioning

confidence: 99%

Interactions between topographically and thermally forced stationary waves: implications for ice-sheet evolution

Liakka

2012

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C TThis study examines mutual interactions between stationary waves and ice sheets using a dry atmospheric primitive-equation model coupled to a three-dimensional thermomechanical ice-sheet model. The emphasis is on how non-linear interactions between thermal and topographical forcing of the stationary waves influence the ice-sheet evolution by changing the ablation. Simulations are conducted in which a small ice cap, on an idealised Northern Hemisphere continent, evolves to an equilibrium continental-scale ice sheet. In the absence of stationary waves, the equilibrium ice sheet arrives at symmetric shape with a zonal equatorward margin. In isolation, the topographically induced stationary waves have essentially no impact on the equilibrium features of the ice sheet. The reason is that the temperature anomalies are located far from the equatorward ice margin. When forcing due to thermal cooling is added to the topographical forcing, thermally induced perturbation winds amplify the topographically induced stationary-wave response, which that serves to increase both the equatorward extent and the volume of the ice sheet. Roughly, a 10% increase in the ice volume is reported here. Hence, the present study suggests that the topographically induced stationary-wave response can be substantially enhanced by the high albedo of ice sheets.

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“…Due to the difference of resolution between the atmospheric and the ice-sheet models, temperature is vertically corrected using a linear vertical gradient of 6 K km −1 . Precipitation is also vertically corrected using an exponential function of the temperature (Charbit et al, 2002(Charbit et al, , 2007. Snowfall is recalculated using the downscaled precipitation and temperature because the more detailed topography of GRISLI allows snowfall when LMDZ5 provides only liquid precipitation.…”

Section: In Case Of No Initial Fennoscandian Ice Sheetmentioning

confidence: 99%

How might the North American ice sheet influence the northwestern Eurasian climate?

et al. 2015

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Abstract.It is now widely acknowledged that past Northern Hemisphere ice sheets covering Canada and northern Europe at the Last Glacial Maximum (LGM) exerted a strong influence on climate by causing changes in atmospheric and oceanic circulations. In turn, these changes may have impacted the development of the ice sheets themselves through a combination of different feedback mechanisms. The present study is designed to investigate the potential impact of the North American ice sheet on the surface mass balance (SMB) of the Eurasian ice sheet driven by simulated changes in the past glacial atmospheric circulation. Using the LMDZ5 atmospheric circulation model, we carried out 12 experiments under constant LGM conditions for insolation, greenhouse gases and ocean. In these experiments, the Eurasian ice sheet is removed. The 12 experiments differ in the North American ice-sheet topography, ranging from a white and flat (present-day topography) ice sheet to a fullsize LGM ice sheet. This experimental design allows the albedo and the topographic impacts of the North American ice sheet onto the climate to be disentangled. The results are compared to our baseline experiment where both the North American and the Eurasian ice sheets have been removed. In summer, the sole albedo effect of the American ice sheet modifies the pattern of planetary waves with respect to the no-ice-sheet case, resulting in a cooling of the northwestern Eurasian region. By contrast, the atmospheric circulation changes induced by the topography of the North American ice sheet lead to a strong decrease of this cooling. In winter, the Scandinavian and the Barents-Kara regions respond differently to the American ice-sheet albedo effect: in response to atmospheric circulation changes, Scandinavia becomes warmer and total precipitation is more abundant, whereas the Barents-Kara area becomes cooler with a decrease of convective processes, causing a decrease of total precipitation. The gradual increase of the altitude of the American ice sheet leads to less total precipitation and snowfall and to colder temperatures over both the Scandinavian and the Barents and Kara sea sectors. We then compute the resulting annual surface mass balance over the Fennoscandian region from the simulated temperature and precipitation fields used to force an ice-sheet model. It clearly appears that the SMB is dominated by the ablation signal. In response to the summer cooling induced by the American ice-sheet albedo, high positive SMB values are obtained over the Eurasian region, leading thus to the growth of an ice sheet. On the contrary, the gradual increase of the American ice-sheet altitude induces more ablation over the Eurasian sector, hence limiting the growth of Fennoscandia. To test the robustness of our results with respect to the Eurasian ice sheet state, we carried out two additional LMDZ experiments with new boundary conditions involving both the American (flat or full LGM) and high Eurasian ice sheets. The most striking result is that the Eurasian ice sheet is...

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

Cited by 117 publications

References 69 publications

Warm Nordic Seas delayed glacial inception in Scandinavia

Warm Nordic Seas delayed glacial inception in Scandinavia

Interactions between topographically and thermally forced stationary waves: implications for ice-sheet evolution

How might the North American ice sheet influence the northwestern Eurasian climate?

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