Recent Progress in Greenland Ice Sheet Modelling

Goelzer, Heiko; Robinson, Alexander; Seroussi, H. L.; Wal, R. S. W. van de

doi:10.1007/s40641-017-0073-y

Cited by 60 publications

(70 citation statements)

References 123 publications

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“…Apart from SMB, changes in the discharge of ice from iceberg calving and melt from the fronts of marine-terminating outlet glaciers have the potential to increase the rate at which the GrIS contributes to future SLR and many of these processes are starting to be included in state-of-the-art Greenland ice-sheet models 18 . Calving and frontal melt has already led to ice front retreat along most of the GrIS and acceleration of marine-terminating glaciers since about 2000 19 .…”

Section: Greenland Forcing and Mass-balance Changesmentioning

confidence: 99%

“…While considerable progress has been made over the last decade with respect to understanding processes at the interface between ice sheets, atmosphere and ocean, significant uncertainties in both forcing and response of the ice sheets remain 18,87 . For the AIS, for instance, the majority of present-day mass loss (essentially the ASE) is driven by changes in ocean circulation.…”

Section: Need For Improvementmentioning

confidence: 99%

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The Greenland and Antarctic ice sheets under 1.5 °C global warming

et al. 2018

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Even if anthropogenic warming were constrained to less than 2°C above pre-industrial, the Greenland and Antarctic ice sheets will continue to lose mass this century, with rates similar to those observed over the last decade. However, nonlinear responses cannot be excluded, which may lead to larger rates of mass loss. Furthermore, large uncertainties in future projections still remain, pertaining to knowledge gaps in atmospheric (Greenland) and oceanic (Antarctica) forcing. On millennial time scales, both ice sheets have tipping points at or slightly above the 1.5-2.0°C threshold; for Greenland, this may lead to irreversible mass loss due to 1 the surface mass balance-elevation feedback, while for Antarctica, this could result in a collapse of major drainage basins due to ice-shelf weakening.Projecting future sea-level rise (SLR, Box 1) is primarily hampered by our incomplete knowledge of the contributions of the Greenland and the Antarctic Ice Sheets (GrIS and AIS, respectively), Earth's largest ice masses. In this paper we review the potential contribution of both ice sheets under a strongly mitigated climate change scenario that limits the rise in global near-surface temperature to less than 2°C above pre-industrial (targeting 1.5°C), as agreed at the 21st UNFCCC climate conference in Paris. We base the review on both present-day observed/modelled changes and future forcings according to the RCP2.6 scenario. We use RCP2.6, the most conservative of the four Representative Concentration Pathways of greenhouse gas concentration trajectories adopted by the IPCC for its Fifth Assessment Report, because it is the scenario in the published literature that best approximates to the above warming range. Ice-sheet mass balance is defined as the net result of all mass gains and losses, and surface mass balance (SMB) as the net mass balance at the ice-sheet surface (where a negative mass balance means mass loss), including the firn layer. Hence, SMB does not include dynamical mass loss associated with ice flow at the ice-sheet margin or melting at the ice-ocean interface. Increased ice flow accounts for about one third of the recent GrIS mass loss 1 . For Antarctica, where mass lost through ice discharge past the grounding line (the limit between the grounded ice sheet and floating ice shelf) is roughly evenly shared between oceanic basal melt before reaching the ice front and iceberg calving, increased ice flow accounts for all of the recent mass loss 2,3 .In the following sections we synthesize: (i) the latest available evidence of GrIS and AIS mass balance changes together with possible climate forcings from the atmosphere/ocean; (ii) the expected responses of the ice sheets under conditions of limited (1.5°C) global warming by 2100. In the concluding section, we highlight outstanding issues that require urgent attention by the research community in order to improve projections. Greenland forcing and mass-balance changesGreenland has warmed by ∼5°C in winter and ∼2°C in summer since the mid-1990s 4 , which is more than d...

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Section: Greenland Forcing and Mass-balance Changesmentioning

confidence: 99%

Section: Need For Improvementmentioning

confidence: 99%

The Greenland and Antarctic ice sheets under 1.5 °C global warming

et al. 2018

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“…As a result, several key features of ice flow models have improved greatly, including: (1) the approximation used for the stress balance equations (Figure 3), (2) the discretization of model domains (Figure 4), and (3) the representation of grounding lines and ice front migration. This section summarizes these improvements; for more details on recent ISM development, we refer readers to Goelzer et al (2017) and Pattyn et al (2017).…”

Section: An Improved Generation Of Modelsmentioning

confidence: 99%

Projections of Future Sea Level Contributions from the Greenland and Antarctic Ice Sheets: Challenges Beyond Dynamical Ice Sheet Modeling

Nowicki¹,

Nasa²,

Seroussi³

2018

Oceanog

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“…The results presented here do not include any weighting of the ice flow models based on their agreement with observations or the number of simulations submitted. As explained in previous studies (Goelzer et al, 2017(Goelzer et al, , 2018Seroussi et al, 2019), the range of initialization techniques adopted by models leads to varying biases. Some models are initialized with a long paleoclimate spin-up, giving limited spurious trends but an initial configuration further from the observed state, whereas models initialized with data assimilation of present-day observations can capture these conditions accurately but often have non-495 physical trend in their evolution.…”

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confidence: 98%

“…Ice-ocean interactions in ice shelf cavities are poorly observed and constrained(Dutrieux et al, 2014;Jenkins et al, 2018;Holland et al, 2019), leading to additional limitations on the representation of ocean-induced sub-shelf 510 melt. Finally, despite the progresses in ice sheet numerical modeling over the last decade(Pattyn et al, 2018;Goelzer et al, 2017), significant limitations remain in our understanding of basal sliding, basal hydrology (De Fleurian et al, J. Glaciol.…”

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confidence: 99%

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

Seroussi¹,

Goelzer²,

Morlighem³

2020

Preprint

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Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and inform on the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimated the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes and the forcings employed. This study presents results from 18 simulations from 15 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100, forced with different scenarios from the Cou-5 pled Model Intercomparison Project Phase 5 (CMIP5) representative of the spread in climate model results. The contribution of the Antarctic ice sheet in response to increased warming during this period varies between -7.8 and 30.0 cm of Sea Level Equivalent (SLE). The evolution of the West Antarctic Ice Sheet varies widely among models, with an overall mass loss up to 21.0 cm SLE in response to changes in oceanic conditions. East Antarctica mass change varies between -6.5 and 16.5 cm SLE, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario 10 forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional mass loss of 8 mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the ocean-induced melt rates, the calibration of these melt rates based on oceanic conditions taken outside of ice shelf cavities and the ice sheet dynamic response to these oceanic changes. Results under RCP 2.6 scenario based on two CMIP5 AOGCMs show an overall mass loss of 10 mm SLE compared to simulations done under present-day 15 conditions, with limited mass gain in East Antarctica.

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Recent Progress in Greenland Ice Sheet Modelling

Cited by 60 publications

References 123 publications

The Greenland and Antarctic ice sheets under 1.5 °C global warming

The Greenland and Antarctic ice sheets under 1.5 °C global warming

Projections of Future Sea Level Contributions from the Greenland and Antarctic Ice Sheets: Challenges Beyond Dynamical Ice Sheet Modeling

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

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