Combining ice core records and ice sheet models to explore the evolution of the East Antarctic Ice sheet during the Last Interglacial period

Abstract. The last interglacial period (LIG, ∼ 129–116 thousand years ago) provides the most recent case study of multimillennial polar warming above the preindustrial level and a response of the Greenland and Antarctic ice sheets to this warming, as well as a test bed for climate and ice sheet models. Past changes in Greenland ice sheet thickness and surface temperature during this period were recently derived from the North Greenland Eemian Ice Drilling (NEEM) ice core records, northwest Greenland. The NEEM paradox has emerged from an estimated large local warming above the preindustrial level (7.5 ± 1.8 °C at the deposition site 126 kyr ago without correction for any overall ice sheet altitude changes between the LIG and the preindustrial period) based on water isotopes, together with limited local ice thinning, suggesting more resilience of the real Greenland ice sheet than shown in some ice sheet models. Here, we provide an independent assessment of the average LIG Greenland surface warming using ice core air isotopic composition (δ15N) and relationships between accumulation rate and temperature. The LIG surface temperature at the upstream NEEM deposition site without ice sheet altitude correction is estimated to be warmer by +8.5 ± 2.5 °C compared to the preindustrial period. This temperature estimate is consistent with the 7.5 ± 1.8 °C warming initially determined from NEEM water isotopes but at the upper end of the preindustrial period to LIG temperature difference of +5.2 ± 2.3 °C obtained at the NGRIP (North Greenland Ice Core Project) site by the same method. Climate simulations performed with present-day ice sheet topography lead in general to a warming smaller than reconstructed, but sensitivity tests show that larger amplitudes (up to 5 °C) are produced in response to prescribed changes in sea ice extent and ice sheet topography.

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Where might we find evidence of a Last Interglacial West Antarctic Ice Sheet collapse in Antarctic ice core records?

Global and Planetary Change ◽

10.1016/j.gloplacha.2012.03.004 ◽

2012 ◽

Vol 88-89 ◽

pp. 64-75 ◽

Cited By ~ 13

Author(s):

S.L. Bradley ◽

M. Siddall ◽

G.A. Milne ◽

V. Masson-Delmotte ◽

E. Wolff

Keyword(s):

Ice Core ◽

Ice Sheet ◽

Last Interglacial ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Ice Core Records

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How warm was Greenland during the last interglacial period?

10.5194/cp-2016-28 ◽

2016 ◽

Cited By ~ 4

Author(s):

Amaelle Landais ◽

Valérie Masson-Delmotte ◽

Emilie Capron ◽

Petra M. Langebroek ◽

Pepijn Bakker ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Water Isotopes ◽

Interglacial Period ◽

Last Interglacial ◽

Surface Warming ◽

Last Interglacial Period ◽

Industrial Level

Abstract. The last interglacial period (LIG, ~ 129–116 thousand years ago) provides the most recent case study for multi-millennial polar warming above pre-industrial level and a respective response of the Greenland and Antarctic ice sheets to this warming, as well as a test bed for climate and ice sheet models. Past changes in Greenland ice sheet thickness and surface temperature during this period were recently derived from the NEEM ice core records, North-West Greenland. The NEEM paradox has emerged from an estimated large local warming above pre-industrial level (7.5 ± 1.8 °C at the deposition site 126 ka ago without correction for any overall ice sheet altitude changes between the LIG and pre-industrial) based on water isotopes, together with limited local ice thinning, suggesting more resilience of the real Greenland ice sheet than shown in some ice sheet models. Here, we provide an independent assessment of the average LIG Greenland surface warming using ice core air isotopic composition (δ15N) and relationships between accumulation rate and temperature. The LIG surface temperature at the upstream NEEM deposition site without ice sheet altitude correction is estimated to be warmer by &plus;7 to &plus;11 °C (&plus;8 °C being the most likely estimate according to constraints on past accumulation rate) compared to the pre-industrial period. This temperature estimate is consistent with the 7.5 ± 1.8 °C warming initially determined from NEEM water isotopes. Moreover, we show that under such warm temperatures, melting of snow probably led to a significant firn shrinking by ~ 15 m. Climate simulations performed with present day ice sheet topography lead to much smaller warming but larger amplitudes (up to 5 °C) can be obtained from changes in sea ice extent and ice sheet topography. Still, ice sheet simulations forced by 5 °C surface warming lead to large ice sheet decay that are not compatible with existing data. Our new, independent temperature constrain therefore reinforces the NEEM paradox.

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Limited Retreat of the Wilkes Basin Ice Sheet during the Last Interglacial.

10.5194/egusphere-egu2020-13504 ◽

2020 ◽

Author(s):

Johannes Sutter ◽

Olaf Eisen ◽

Martin Werner ◽

Klaus Grosfeld ◽

Thomas Kleiner ◽

...

Keyword(s):

Sea Level ◽

Ice Core ◽

Ice Sheet ◽

Last Interglacial ◽

Antarctic Ice Sheet ◽

Future Global Warming ◽

Grounding Line ◽

Ice Core Record ◽

East Antarctic Ice Sheet

The response of the marine sectors of the East Antarctic Ice Sheet to future global warming represents a major source of uncertainty in sea level projections. If greenhouse gas emissions continue unbridled, ice loss in these areas may contribute up to several meters to long-term global sea level rise. In East Antarctica, thinning of the ice cover of the George V and Sabrina Coast is currently taking place, and its destabilization in past warm climate periods has been implied. The extent of such past interglacial retreat episodes cannot yet be quantitatively derived from paleo proxy records alone. Ice sheet modelling constrained by paleo observations is therefore critical to assess the stability of the East Antarctic Ice Sheet during warmer climates. We propose that a runaway retreat during the Last Interglacial of the George V Coast grounding line into the Wilkes Subglacial Basin would either leave a clear imprint on the water isotope composition in the neighbouring Talos Dome ice-core record or prohibit the preservation of an ice core record from the Last Interglacial alltogether. We test this hypothesis using a dynamic ice sheet model and infer that the marine Wilkes Basin ice sheet remained stable throughout the Last Interglacial (130,000-120,000 years ago). Our analysis provides the first constraint on Last Interglacial East Antarctic grounding line stability by benchmarking ice sheet model simulations with ice core records. Our findings also imply that ambitious mitigation efforts keeping global temperature rise in check could safeguard this region from irreversible ice loss in the long term.

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Greenland ice sheet contribution to sea level rise during the last interglacial period: a modelling study driven and constrained by ice core data

Climate of the Past ◽

10.5194/cp-9-353-2013 ◽

2013 ◽

Vol 9 (1) ◽

pp. 353-366 ◽

Cited By ~ 42

Author(s):

A. Quiquet ◽

C. Ritz ◽

H. J. Punge ◽

D. Salas y Mélia

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Core ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Interglacial Period ◽

Last Interglacial ◽

Intergovernmental Panel ◽

Orbital Configuration ◽

Global Sea Level

Abstract. As pointed out by the forth assessment report of the Intergovernmental Panel on Climate Change, IPCC-AR4 (Meehl et al., 2007), the contribution of the two major ice sheets, Antarctica and Greenland, to global sea level rise, is a subject of key importance for the scientific community. By the end of the next century, a 3–5 °C warming is expected in Greenland. Similar temperatures in this region were reached during the last interglacial (LIG) period, 130–115 ka BP, due to a change in orbital configuration rather than to an anthropogenic forcing. Ice core evidence suggests that the Greenland ice sheet (GIS) survived this warm period, but great uncertainties remain about the total Greenland ice reduction during the LIG. Here we perform long-term simulations of the GIS using an improved ice sheet model. Both the methodologies chosen to reconstruct palaeoclimate and to calibrate the model are strongly based on proxy data. We suggest a relatively low contribution to LIG sea level rise from Greenland melting, ranging from 0.7 to 1.5 m of sea level equivalent, contrasting with previous studies. Our results suggest an important contribution of the Antarctic ice sheet to the LIG highstand.

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Evolution of the East Antarctic Ice Sheet: A Numerical Study of Thermo-Mechanical Response Patterns With Changing Climate

Annals of Glaciology ◽

10.1017/s0260305500006327 ◽

1988 ◽

Vol 11 ◽

pp. 52-59 ◽

Cited By ~ 58

Author(s):

P. Huybrechts ◽

J. Oerlemans

Keyword(s):

Mechanical Response ◽

Flow Line ◽

Numerical Study ◽

Ice Core ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

Mechanical Coupling ◽

Vostok Station ◽

Basal Melting ◽

East Antarctic Ice Sheet

An efficient numerical ice-sheet model, including time dependence and full thermo-mechanical coupling, has been developed in order to investigate the thermal regime and overall configuration of a polar ice sheet with respect to changing environmental conditions. From basic sensitivity experiments, in which a schematic East Antarctic ice sheet is forced with a typical glacial–interglacial climatic shift, it is found that: (i) the mutual interaction of temperature and deformation has a stabilizing effect on its steady-state configuration; (ii) in the transient mode, this climatic transition initially leads to increased ice thickness due to enhanced accumulation, after which this trend is reversed due to a warmer base. Time-scales for this reversal are of the order of 103 years in marginal zones and of 104 years in interior regions; (iii) horizontal heat advection plays a major role in damping possible runaway behaviour due to the dissipation – strain-rate feed-back, suggesting that creep instability is a rather unlikely candidate to initiate surging of the East Antarctic ice sheet. The model is then applied to four East Antarctic flow lines. Only the flow line passing through Wilkes Land appears to be vulnerable to widespread basal melting, due to enhanced basal warming following climatic warming. Time-dependent modelling of the Vostok flow line indicates that the Vostok Station area has risen about 95 m since the beginning of the present interglacial due to thermo-mechanical effects, which is of particular interest in interpreting the palaeoclimatic signal of the ice core obtained there.

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Evolution of the East Antarctic Ice Sheet: A Numerical Study of Thermo-Mechanical Response Patterns With Changing Climate

Annals of Glaciology ◽

10.3189/s0260305500006327 ◽

1988 ◽

Vol 11 ◽

pp. 52-59 ◽

Cited By ~ 16

Author(s):

P. Huybrechts ◽

J. Oerlemans

Keyword(s):

Mechanical Response ◽

Flow Line ◽

Numerical Study ◽

Ice Core ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

Mechanical Coupling ◽

Vostok Station ◽

Basal Melting ◽

East Antarctic Ice Sheet

An efficient numerical ice-sheet model, including time dependence and full thermo-mechanical coupling, has been developed in order to investigate the thermal regime and overall configuration of a polar ice sheet with respect to changing environmental conditions.From basic sensitivity experiments, in which a schematic East Antarctic ice sheet is forced with a typical glacial–interglacial climatic shift, it is found that: (i) the mutual interaction of temperature and deformation has a stabilizing effect on its steady-state configuration; (ii) in the transient mode, this climatic transition initially leads to increased ice thickness due to enhanced accumulation, after which this trend is reversed due to a warmer base. Time-scales for this reversal are of the order of 103 years in marginal zones and of 104 years in interior regions; (iii) horizontal heat advection plays a major role in damping possible runaway behaviour due to the dissipation – strain-rate feed-back, suggesting that creep instability is a rather unlikely candidate to initiate surging of the East Antarctic ice sheet.The model is then applied to four East Antarctic flow lines. Only the flow line passing through Wilkes Land appears to be vulnerable to widespread basal melting, due to enhanced basal warming following climatic warming. Time-dependent modelling of the Vostok flow line indicates that the Vostok Station area has risen about 95 m since the beginning of the present interglacial due to thermo-mechanical effects, which is of particular interest in interpreting the palaeoclimatic signal of the ice core obtained there.

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Greenland warming during the last interglacial: the relative importance of insolation and oceanic changes

10.5194/cp-2016-48 ◽

2016 ◽

Cited By ~ 1

Author(s):

Rasmus A. Pedersen ◽

Peter L. Langen ◽

Bo M. Vinther

Keyword(s):

General Circulation ◽

Ice Core ◽

Ice Sheet ◽

Circulation Model ◽

The Arctic ◽

Balance Model ◽

Interglacial Period ◽

Last Interglacial ◽

Ice Core Record ◽

The Impact

Abstract. Insolation changes during the Eemian (the last interglacial period, 129–116 000 years before present) resulted in warmer than present conditions in the Arctic region. The NEEM ice core record suggests warming of 8±4 K in northwestern Greenland based on water stable isotopes. Here we use general circulation model experiments to investigate the causes of the Eemian warming in Greenland. Simulations of the atmospheric response to combinations of Eemian insolation and pre-industrial oceanic conditions and vice versa, are used to disentangle the impacts of the insolation change and the related changes in sea surface temperatures and sea ice conditions. The changed oceanic conditions cause warming throughout the year, prolonging the impact of the summertime insolation increase. Consequently, the oceanic conditions cause annual mean warming of 2 K at the NEEM site, whereas the insolation alone causes an insignificant change. Taking the precipitation changes into account, however, the insolation and oceanic changes cause more comparable increases in the precipitation-weighted temperature, implying that both contributions are important for the ice core record at the NEEM site. The simulated Eemian precipitation-weighted warming of 2.4 K at the NEEM site is low compared to the ice core reconstruction, partially due to missing feedbacks related to ice sheet changes. Surface mass balance calculations with an energy balance model indicate potential mass loss in the north and southwestern parts of the ice sheet. The oceanic conditions favor increased accumulation in the southeast, while the insolation appears to be the dominant cause of the expected ice sheet reduction.

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Reconciling reconstructions and simulations of the Greenland ice sheet and its climate during the Last Interglacial period

10.5194/egusphere-egu2020-19016 ◽

2020 ◽

Author(s):

Alexander Robinson ◽

Emilie Capron ◽

Jorge Alvarez-Solas ◽

Michael Bender ◽

Heiko Goelzer ◽

...

Keyword(s):

Climate Change ◽

Sea Level ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Future Climate Change ◽

Interglacial Period ◽

Last Interglacial ◽

Proxy Data ◽

Last Interglacial Period

There is still no consensus concerning the evolution of the Greenland ice sheet during the Last Interglacial period (LIG, 130-115 kyr ago). Ice cores indicate that the ice sheet survived over most of the continent. Proxy data indicate temperature anomalies of up to 6-8&#176;C. However, under these conditions, models predict almost complete deglaciation. This paradox must be resolved to be able to quantify Greenland&#8217;s sea-level contribution during the LIG as well as to understand its sensitivity to future climate change. Here we analyze the available evidence and outline strategies to reconcile modeling and data efforts for Greenland during the LIG.

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Inferring the Last Interglacial West Antarctic Ice Sheet from the coupling of an ice core water stable isotope record and an atmospheric general circulation model

10.5194/egusphere-egu2020-16787 ◽

2020 ◽

Author(s):

Sentia Goursaud ◽

Louise Sime ◽

Eric Wolff

Keyword(s):

General Circulation ◽

Ice Core ◽

Ice Sheet ◽

Circulation Model ◽

Last Interglacial ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Isotope Record ◽

Water Stable Isotope

The Last Interglacial period (130-115 ka BP, hereafter LIG) is often considered as a prime example to study the effect of warmer-than-present temperatures on polar ice sheets evolution. As the debate mainly focuses on the causes and tipping point of a potential collapse of the West Antarctic Ice Sheet (hereafter WAIS), few investigations examine the consequences of a wais collapse in terms of atmospheric circulation. However, a knowledge of the state of the atmosphere is necessary to use proxy data recorded in ice cores. By analysing a new ice core drilled in Skytrain ice rise and using climate modeling, the WACSWAIN (WArm Climate Stability of West Antarctic ice sheet in the last Interglacial) aims to reconstruct WAIS extent during the LIG. Here, we use simulations from the atmospheric general circulation model HadCM3 with different WAIS configurations. We show that changes in temperature are directly linked to changes in orography through thermodynamic effects, as well as a linear sea ice extent rise over the Pacific Ocean with the WAIS reduction explained by a reversal of meridional winds turning southwards as the WAIS disappears. At the Skytrain ice rise, we show that not only the isotopic thermometer can be applied, but we also suggest that the water stable isotope record imprinted in the ice core will allow us to quantify the wais reduction.

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