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

2013 ◽  
Vol 9 (1) ◽  
pp. 353-366 ◽  
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.

scholarly journals Coupled regional climate–ice-sheet simulation shows limited Greenland ice loss during the Eemian

2013 ◽  
Vol 9 (4) ◽  
pp. 1773-1788 ◽  
Author(s):  
M. M. Helsen ◽  
W. J. van de Berg ◽  
R. S. W. van de Wal ◽  
M. R. van den Broeke ◽  
J. Oerlemans
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Temperature Record ◽  
Last Interglacial ◽  
Central Dome

Abstract. During the last interglacial period (Eemian, 130–115 kyr BP) eustatic global sea level likely peaked at > 6 m above the present-day level, but estimates of the contribution of the Greenland Ice Sheet vary widely. Here we use an asynchronously two-way-coupled regional climate–ice-sheet model, which includes physically realistic feedbacks between the changing ice sheet topography and climate forcing. Our simulation results in a contribution from the Greenland Ice Sheet to the Eemian sea level highstand between 1.2 and 3.5 m, with a most likely value of 2.1 m. Simulated Eemian ice loss in Greenland is dominated by the rapid retreat of the southwestern margin; two-thirds of the ice loss occurred south of 70° N. The southern dome survived the Eemian and remained connected to the central dome. Large-scale ice sheet retreat is prevented in areas with high accumulation. Our results broadly agree with ice-core-inferred elevation changes and marine records, but it does not match with the ice-core-derived temperature record from northern Greenland. During maximum Eemian summertime insolation, Greenland mass loss contributed ~ 0.5 m kyr−1 to sea level rise, 24% of the reconstructed total rate of sea level rise. Next to that, a difference of > 3 m remains between our maximum estimate of the Greenland contribution and the reconstructed minimum value of the global eustatic Eemian highstand. Hence, the Antarctic Ice Sheet must also have contributed significantly to this sea level highstand.

scholarly journals Contribution of Greenland ice sheet melting to sea level rise during the last interglacial period: an approach combining ice sheet modelling and proxy data

2012 ◽  
Vol 8 (4) ◽  
pp. 3345-3377
Author(s):  
A. Quiquet ◽  
C. Ritz ◽  
H. J. Punge ◽  
D. Salas y Mélia
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Proxy Data ◽  
Intergovernmental Panel ◽  
Period Range ◽  
Ice Sheet Modelling

Abstract. In the context of global warming, 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 (4th assessment report of the Intergovernmental Panel on climate change, IPCC-AR4, Meehl et al., 2007). By the end of the next century, a 3–5 °C warm up is expected in Greenland. Similar temperatures in this region were reached during the last interglacial (LIG) period due to a change in orbital configuration rather than to anthropogenic forcing. Ice core evidence suggests that the Greenland Ice Sheet (GIS) has survived this warm period but great uncertainties remain about the total Greenland ice reduction during the LIG and its sea level rise contribution. In order to improve our confidence in future state projections, we first intend to reconstruct the past states of the GIS using ice sheet modelling, and confront the simulations with paleo data. The chosen methodoly of paleoclimate reconstruction is strongly based on proxy data. Proxy data are also used to constrain the ice sheet model during the calibration phase. Our estimates of Greenland melting contribution to sea level rise during the LIG period range from 0.65 to 1.5 m of sea level equivalent.

scholarly journals Quantification of the Greenland ice sheet contribution to Last Interglacial sea level rise

2013 ◽  
Vol 9 (2) ◽  
pp. 621-639 ◽  
Author(s):  
E. J. Stone ◽  
D. J. Lunt ◽  
J. D. Annan ◽  
J. C. Hargreaves
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
The Arctic ◽  
Substantial Contribution ◽  
Interglacial Period ◽  
Last Interglacial

Abstract. During the Last Interglacial period (~ 130–115 thousand years ago) the Arctic climate was warmer than today, and global mean sea level was probably more than 6.6 m higher. However, there are large discrepancies in the estimated contributions to this sea level change from various sources (the Greenland and Antarctic ice sheets and smaller ice caps). Here, we determine probabilistically the likely contribution of Greenland ice sheet melt to Last Interglacial sea level rise, taking into account ice sheet model parametric uncertainty. We perform an ensemble of 500 Glimmer ice sheet model simulations forced with climatologies from the climate model HadCM3, and constrain the results with palaeodata from Greenland ice cores. Our results suggest a 90% probability that Greenland ice melt contributed at least 0.6 m, but less than 10% probability that it exceeded 3.5 m, a value which is lower than several recent estimates. Many of these previous estimates, however, did not include a full general circulation climate model that can capture atmospheric circulation and precipitation changes in response to changes in insolation forcing and orographic height. Our combined modelling and palaeodata approach suggests that the Greenland ice sheet is less sensitive to orbital forcing than previously thought, and it implicates Antarctic melt as providing a substantial contribution to Last Interglacial sea level rise. Future work should assess additional uncertainty due to inclusion of basal sliding and the direct effect of insolation on surface melt. In addition, the effect of uncertainty arising from climate model structural design should be taken into account by performing a multi-climate-model comparison.

scholarly journals Coupled regional climate–ice sheet simulation shows limited Greenland ice loss during the Eemian

2013 ◽  
Vol 9 (2) ◽  
pp. 1735-1770 ◽  
Author(s):  
M. M. Helsen ◽  
W. J. van de Berg ◽  
R. S. W. van de Wal ◽  
M. R. van den Broeke ◽  
J. Oerlemans
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Large Scale ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Temperature Record ◽  
Last Interglacial ◽  
Central Dome

Abstract. During the last interglacial (Eemian, 130–115 kyr BP) eustatic global sea level likely peaked at >6 m above the present-day level, but estimates of the contribution of the Greenland ice sheet vary widely. Here we use an asynchronously two-way coupled regional climate–ice sheet model, which includes physically realistic feedbacks between the changing ice sheet topography and climate forcing. Our simulation results in a contribution from the Greenland ice sheet to the Eemian sea level highstand between 1.2 and 3.5 m, with a most likely value of 2.1 m. Simulated Eemian ice loss in Greenland is dominated by the rapid retreat of the southwestern margin: two-thirds of the ice loss occurred south of 70° N. The southern dome survived the Eemian and remained connected to the central dome. Large-scale ice sheet retreat is prevented in areas with high accumulation. Our results broadly agree with ice core inferred elevation changes and marine records, but it does not match with the ice-core derived temperature record from northern Greenland. During maximum Eemian summertime insolation, Greenland mass loss contributed ~0.5 m kyr−1 to sea level rise, 24% of the reconstructed total rate of sea level rise. Next to that, a difference of >3 m remains between our maximum estimate of the Greenland contribution and the reconstructed minimum value of the global eustatic Eemian highstand. Hence, the Antarctic ice sheet must also have contributed significantly to this sea level highstand.

scholarly journals Moderate Greenland ice sheet melt during the last interglacial constrained by present-day observations and paleo ice core reconstructions

2016 ◽  
Author(s):  
P.M. Langebroek ◽  
K.H. Nisancioglu
Keyword(s):  
Sea Level ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Atmospheric Temperature ◽  
Lapse Rate ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Temperature Lapse Rate

Abstract. During the last interglacial period (LIG, ~ 130–115 ka before present, ka = 1000 yr) summer temperatures over Greenland were several degrees higher than today. It is likely that the Greenland ice sheet (GIS) was smaller than today, contributing to the reconstructed sea-level highstand of the LIG. However, the range of simulated GIS melt is large, and the location of the melt is uncertain. Here, we use temperature and precipitation patterns simulated by the Norwegian Earth System Model (NorESM) to investigate the volume, extent and stability of the GIS during the LIG. Present-day observations of ice sheet size, elevation and stability, together with paleo elevation information from five deep ice cores, are used to evaluate our ensemble of GIS simulations. Accepted simulations indicate a maximum GIS reduction equivalent to a global mean sea-level rise of 0.8–2.2 m compared to today, with most of the melt occurring in the southwest. The timing of the maximum ice melt over Greenland is simulated between 124 and 122 ka. We furthermore suggest a preferred mean value for the basal sliding parameter, relatively high PDD factors and an average to high atmospheric temperature lapse rate based on training the SICOPOLIS ice sheet model to observations and available LIG proxy data.

scholarly journals Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Eelco J. Rohling ◽  
Fiona D. Hibbert ◽  
Katharine M. Grant ◽  
Eirik V. Galaasen ◽  
Nil Irvalı ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Temporal Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Present Level ◽  
Last Interglacial ◽  
Ice Shelf ◽  
Ice Volume ◽  
Global Sea Level

Abstract The last interglacial (LIG; ~130 to ~118 thousand years ago, ka) was the last time global sea level rose well above the present level. Greenland Ice Sheet (GrIS) contributions were insufficient to explain the highstand, so that substantial Antarctic Ice Sheet (AIS) reduction is implied. However, the nature and drivers of GrIS and AIS reductions remain enigmatic, even though they may be critical for understanding future sea-level rise. Here we complement existing records with new data, and reveal that the LIG contained an AIS-derived highstand from ~129.5 to ~125 ka, a lowstand centred on 125–124 ka, and joint AIS + GrIS contributions from ~123.5 to ~118 ka. Moreover, a dual substructure within the first highstand suggests temporal variability in the AIS contributions. Implied rates of sea-level rise are high (up to several meters per century; m c−1), and lend credibility to high rates inferred by ice modelling under certain ice-shelf instability parameterisations.

scholarly journals How warm was Greenland during the last interglacial period?

2016 ◽  
Vol 12 (9) ◽  
pp. 1933-1948 ◽  
Author(s):  
Amaelle Landais ◽  
Valérie Masson-Delmotte ◽  
Emilie Capron ◽  
Petra M. Langebroek ◽  
Pepijn Bakker ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Water Isotopes ◽  
Interglacial Period ◽  
Last Interglacial ◽  
Last Interglacial Period ◽  
Ice Sheet Topography ◽  
North Greenland

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.

Greenland ice sheet hydrology

2013 ◽  
Vol 38 (1) ◽  
pp. 19-54 ◽  
Author(s):  
Vena W. Chu
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Field Studies ◽  
Ice Dynamics ◽  
Surface Water Hydrology ◽  
Basal Sliding ◽  
Hydrologic System ◽  
Global Sea Level

Understanding Greenland ice sheet (GrIS) hydrology is essential for evaluating response of ice dynamics to a warming climate and future contributions to global sea level rise. Recently observed increases in temperature and melt extent over the GrIS have prompted numerous remote sensing, modeling, and field studies gauging the response of the ice sheet and outlet glaciers to increasing meltwater input, providing a quickly growing body of literature describing seasonal and annual development of the GrIS hydrologic system. This system is characterized by supraglacial streams and lakes that drain through moulins, providing an influx of meltwater into englacial and subglacial environments that increases basal sliding speeds of outlet glaciers in the short term. However, englacial and subglacial drainage systems may adjust to efficiently drain increased meltwater without significant changes to ice dynamics over seasonal and annual scales. Both proglacial rivers originating from land-terminating glaciers and subglacial conduits under marine-terminating glaciers represent direct meltwater outputs in the form of fjord sediment plumes, visible in remotely sensed imagery. This review provides the current state of knowledge on GrIS surface water hydrology, following ice sheet surface meltwater production and transport via supra-, en-, sub-, and proglacial processes to final meltwater export to the ocean. With continued efforts targeting both process-level and systems analysis of the hydrologic system, the larger picture of how future changes in Greenland hydrology will affect ice sheet glacier dynamics and ultimately global sea level rise can be advanced.

scholarly journals Extraordinary runoff from the Greenland ice sheet in 2012 amplified by hypsometry and depleted firn retention

2016 ◽  
Vol 10 (3) ◽  
pp. 1147-1159 ◽  
Author(s):  
Andreas Bech Mikkelsen ◽  
Alun Hubbard ◽  
Mike MacFerrin ◽  
Jason Eric Box ◽  
Sam H. Doyle ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Equilibrium Line ◽  
Aerial Photographs ◽  
Discharge Data ◽  
Impermeable Barrier ◽  
Global Sea Level ◽  
Percolation Zone

Abstract. It has been argued that the infiltration and retention of meltwater within firn across the percolation zone of the Greenland ice sheet has the potential to buffer up to  ∼  3.6 mm of global sea-level rise (Harper et al., 2012). Despite evidence confirming active refreezing processes above the equilibrium line, their impact on runoff and proglacial discharge has yet to be assessed. Here, we compare meteorological, melt, firn stratigraphy and discharge data from the extreme 2010 and 2012 summers to determine the relationship between atmospheric forcing and melt runoff at the land-terminating Kangerlussuaq sector of the Greenland ice sheet, which drains into the Watson River. The 6.8 km3 bulk discharge in 2012 exceeded that in 2010 by 28 %, despite only a 3 % difference in net incoming melt energy between the two years. This large disparity can be explained by a 10 % contribution of runoff originating from above the long-term equilibrium line in 2012 caused by diminished firn retention. The amplified 2012 response was compounded by catchment hypsometry; the disproportionate increase in area contributing to runoff as the melt-level rose high into the accumulation area.Satellite imagery and aerial photographs reveal an extensive supraglacial network extending 140 km from the ice margin that confirms active meltwater runoff originating well above the equilibrium line. This runoff culminated in three days with record discharge of 3100 m3 s−1 (0.27 Gt d−1) that peaked on 11 July and washed out the Watson River Bridge. Our findings corroborate melt infiltration processes in the percolation zone, though the resulting patterns of refreezing are complex and can lead to spatially extensive, perched superimposed ice layers within the firn. In 2012, such layers extended to an elevation of at least 1840 m and provided a semi-impermeable barrier to further meltwater storage, thereby promoting widespread runoff from the accumulation area of the Greenland ice sheet that contributed directly to proglacial discharge and global sea-level rise.

Trends and projections in ice sheet mass balance

2020 ◽  
Author(s):  
Andrew Shepherd ◽  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Sea Levels ◽  
Global Sea Level

<p>In recent decades, the Antarctic and Greenland Ice Sheets have been major contributors to global sea-level rise and are expected to be so in the future. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the degree and trajectory of today’s imbalance remain uncertain. Here we compare and combine 26 individual satellite records of changes in polar ice sheet volume, flow and gravitational potential to produce a reconciled estimate of their mass balance. <strong>Since the early 1990’s, ice losses from Antarctica and Greenland have caused global sea-levels to rise by 18.4 millimetres, on average, and there has been a sixfold increase in the volume of ice loss over time. Of this total, 41 % (7.6 millimetres) originates from Antarctica and 59 % (10.8 millimetres) is from Greenland. In this presentation, we compare our reconciled estimates of Antarctic and Greenland ice sheet mass change to IPCC projection of sea level rise to assess the model skill in predicting changes in ice dynamics and surface mass balance.  </strong>Cumulative ice losses from both ice sheets have been close to the IPCC’s predicted rates for their high-end climate warming scenario, which forecast an additional 170 millimetres of global sea-level rise by 2100 when compared to their central estimate.</p>

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