ISMIP6 Future Projections for Antarctica performed using the AWI PISM ice sheet model

2020 ◽  
Author(s):  
Thomas Kleiner ◽  
Jeremie Schmiedel ◽  
Angelika Humbert
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Climate Models ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Initial State ◽  
Intercomparison Project ◽  
Non Local ◽  
The Impact

<p>Ice sheets constitute the largest and most uncertain potential source of future sea-level rise. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) brings together a consortium of international ice sheet and climate models to explore the contribution from the Greenland and Antarctic ice sheets to future sea-level rise.</p> <p>We use the Parallel Ice Sheet Model (PISM, pism-docs.org) to carry out spinup and projection simulations for the Antarctic Ice Sheet. Our treatment of the ice-ocean boundary condition previously based on 3D ocean temperatures (initMIP-Antarctica) has been adopted to use the ISMIP6 parameterisation and 3D ocean forcing fields (temperature and salinity) according to the ISMIP6 protocol.</p> <p>In this study, we analyse the impact of the choices made during the model initialisation procedure on the initial state. We present the AWI PISM results of the ISMIP6 projection simulations and investigate the ice sheet response for individual basins. In the analysis, we distinguish between the local and non-local ice shelf basal melt parameterisation.</p>

scholarly journals Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) – experimental design

2012 ◽  
Vol 5 (4) ◽  
pp. 963-974 ◽  
Author(s):  
A. M. Dolan ◽  
S. J. Koenig ◽  
D. J. Hill ◽  
A. M. Haywood ◽  
R. M. DeConto
Keyword(s):  
Experimental Design ◽  
Sea Level ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Warm Period ◽  
Modern World ◽  
Intercomparison Project ◽  
Ice Sheet Modelling

Abstract. During the mid-Pliocene warm period (3.264 to 3.025 million years ago), global mean temperature was similar to that predicted for the next century and atmospheric carbon dioxide concentrations were slightly higher than today. Sea level was also higher than today, implying a reduction in the extent of the ice sheets. Thus, the mid-Pliocene warm period (mPWP) provides a unique testing ground to investigate the stability of the Earth's ice sheets and their contribution to sea level in a warmer-than-modern world. Climate models and ice sheet models can be used to enhance our understanding of ice sheet stability; however, uncertainties associated with different ice-sheet modelling frameworks mean that a rigorous comparison of numerical ice sheet model simulations for the Pliocene is essential. As an extension to the Pliocene Model Intercomparison Project (PlioMIP; Haywood et al., 2010, 2011a), the Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) will provide the first assessment as to the ice sheet model dependency of ice sheet predictions for the mPWP. Here we outline the PLISMIP experimental design and initialisation conditions that have been adopted to simulate the Greenland and Antarctic ice sheets under present-day and warm mid-Pliocene conditions. Not only will this project provide a new benchmark in the simulation of ice sheets in a past warm period, but the analysis of model sensitivity to various uncertainties could directly inform future predictions of ice sheet and sea level change.

scholarly journals Simulation of the Greenland Ice sheet over two glacial cycles: Investigating a sub-ice shelf melt parameterisation and relative sea level forcing in an ice sheet-ice shelf model

2017 ◽  
Author(s):  
Sarah L. Bradley ◽  
Thomas J. Reerink ◽  
Roderik S. W. van de Wal ◽  
Michiel M. Helsen
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Shelf ◽  
Temporal Behaviour ◽  
The North ◽  
Non Local ◽  
Continental Shelf Break

Abstract. Observational evidence, including offshore moraines and sediment cores confirm that at the Last Glacial maximum (LGM) the Greenland ice sheet (GrIS) grew to a significantly larger spatial extent than seen at present, grounding into Baffin Bay and to the continental shelf break. Given this larger spatial extent and it is close proximity to the neighboring Laurentide (LIS) and Innuitian Ice sheet (IIS), it is likely these ice sheets will have had a strong non-local influence on the spatial and temporal behaviour of the GrIS. Most previous paleo ice sheet modelling simulations recreated an ice sheet that either did not extend out onto the continental shelf; or utilized a simplified marine ice parametersiation and therefore did not fully include ice shelf dynamics, and or the sensitivity of the GrIS to this non-local signal from the surrounding ice sheets. In this paper, we investigated the evolution of the GrIS over the two most recent glacial-interglacial cycles (240 kyr BP to present day), using the ice sheet-ice shelf model, IMAU-ICE and investigated the influence of the LIS and IIS via an offline relative sea level (RSL) forcing generated by a GIA model. This RSL forcing controlled via changes in the water depth below the developing ice shelves, the spatial and temporal pattern of sub-ice shelf melting, which was parametrised in relation to changes in water depth. In the suite of simulations, the GrIS at the glacial maximums coalesced with the IIS to the north, expanded to the continental shelf break to the south west but remained too restricted to the north east. In terms of an ice-volume equivalent sea level contribution, at the Last Interglacial (LIG) and LGM the ice sheet added 1.46 m and −2.59 m to the budget respectively. The estimated lowering of the sea level by the Greenland contribution is considerably more (1.26 m) than most previous studies indicated whereas the contribution to the LIG high stand is lower (0.7 m). The spatial and temporal behaviour of the northern margin was highly variable in all simulations, controlled by the sub surface melt (SSM), which was dictated by the RSL forcing and the glacial history of the IIS and LIS. In contrast, the southwestern part of the ice sheet was insensitive to these forcing’s, with a uniform response in an all simulations controlled by the surface air temperature (SAT) forcing, derived from ice cores.

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

2020 ◽  
Author(s):  
Eelco Rohling ◽  
Fiona Hibbert
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Global Climate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Climate Forcing ◽  
Potential Contribution ◽  
Last Interglacial ◽  
Ice Shelf

<p>Sea-level rise is among the greatest risks that arise from anthropogenic global climate change. It is receiving a lot of attention, among others in the IPCC reports, but major questions remain as to the potential contribution from the great continental ice sheets. In recent years, some modelling work has suggested that the ice-component of sea-level rise may be much faster than previously thought, but the rapidity of rise seen in these results depends on inclusion of scientifically debated mechanisms of ice-shelf decay and associated ice-sheet instability. The processes have not been active during historical times, so data are needed from previous warm periods to evaluate whether the suggested rates of sea-level rise are supported by observations or not. Also, we then need to assess which of the ice sheets was most sensitive, and why. The last interglacial (LIG; ~130,000 to ~118,000 years ago, ka) was the last time global sea level rose well above its present level, reaching a highstand of +6 to +9 m or more. Because Greenland Ice Sheet (GrIS) contributions were smaller than that, this implies substantial Antarctic Ice Sheet (AIS) contributions. However, this still leaves the timings, magnitudes, and drivers of GrIS and AIS reductions open to debate. I will discuss recently published sea-level reconstructions for the LIG highstand, which reveal that AIS and GrIS contributions were distinctly asynchronous, and that rates of rise to values above 0 m (present-day sea level) reached up to 3.5 m per century. Such high pre-anthropogenic rates of sea-level rise lend credibility to high rates inferred by ice modelling under certain ice-shelf instability parameterisations, for both the past and future. Climate forcing was distinctly asynchronous between the southern and northern hemispheres as well during the LIG, explaining the asynchronous sea-level contributions from AIS and GrIS. Today, climate forcing is synchronous between the two hemispheres, and also faster and greater than during the LIG. Therefore, LIG rates of sea-level rise should likely be considered minimum estimates for the future.</p>

Doubling of future Greenland Ice Sheet surface melt revealed by the new CMIP6 high-emission scenario

2020 ◽  
Author(s):  
Stefan Hofer ◽  
Charlotte Lang ◽  
Charles Amory ◽  
Christoph Kittel ◽  
Alison Delhasse ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Radiative Forcing ◽  
Climate Models ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Cmip5 Models ◽  
Surface Melt ◽  
The Impact

<p>Future climate projections show a marked increase in Greenland Ice Sheet (GrIS) runoff<br>during the 21st century, a direct consequence of the Polar Amplification signal. Regional<br>climate models (RCMs) are a widely used tool to downscale ensembles of projections from<br>global climate models (GCMs) to assess the impact of global warming on GrIS melt and<br>sea level rise contribution. Initial results of the CMIP6 GCM model intercomparison<br>project have revealed a greater 21st century temperature rise than in CMIP5 models.<br>However, so far very little is known about the subsequent impacts on the future GrIS<br>surface melt and therefore sea level rise contribution. Here, we show that the total GrIS<br>melt during the 21st century almost doubles when using CMIP6 forcing compared to the<br>previous CMIP5 model ensemble, despite an equal global radiative forcing of +8.5 W/m2<br>in 2100 in both RCP8.5 and SSP58.5 scenarios. The total GrIS sea level rise contribution<br>from surface melt in our high-resolution (15 km) projections is 17.8 cm in SSP58.5, 7.9 cm<br>more than in our RCP8.5 simulations, despite the same radiative forcing. We identify a<br>+1.7°C greater Arctic amplification in the CMIP6 ensemble as the main driver behind the<br>presented doubling of future GrIS sea level rise contribution</p>

scholarly journals Ice Sheet Model Intercomparison Project (ISMIP6) contribution to CMIP6

2016 ◽  
Author(s):  
Sophie M. J. Nowicki ◽  
Tony Payne ◽  
Eric Larour ◽  
Helene Seroussi ◽  
Heiko Goelzer ◽  
...  
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Coupled Model ◽  
Sea Level Change ◽  
Model Intercomparison ◽  
Sea Level Changes ◽  
Level Change ◽  
Intercomparison Project

Abstract. Reducing the uncertainty in the past, present and future contribution of ice sheets to sea level change requires a coordinated effort between the climate and glaciology communities. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is the primary activity within the Coupled Model Intercomparison Project – phase 6 (CMIP6) focusing on the Greenland and Antarctic Ice Sheets. In this paper, we describe the framework for ISMIP6 and its relationship to other activities within CMIP6. The ISMIP6 experimental design relies on CMIP6 climate models and includes, for the first time within CMIP, coupled ice sheet – climate models as well as standalone ice sheet models. To facilitate analysis of the multi-model ensemble and to generate a set of standard climate inputs for standalone ice sheet models, ISMIP6 defines a protocol for all variables related to ice sheets. ISMIP6 will provide a basis for investigating the feedbacks, impacts, and sea level changes associated with dynamic ice sheets and for quantifying the uncertainty in ice-sheet-sourced global sea level change.

scholarly journals Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) – experimental design

2011 ◽  
Vol 4 (4) ◽  
pp. 2661-2686 ◽  
Author(s):  
A. M. Dolan ◽  
S. J. Koenig ◽  
D. J. Hill ◽  
A. M. Haywood ◽  
R. M. DeConto
Keyword(s):  
Experimental Design ◽  
Sea Level ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Warm Period ◽  
Modern World ◽  
Intercomparison Project ◽  
Ice Sheet Modelling

Abstract. During the mid-Pliocene Warm Period (3.264 to 3.025 million yr ago), global mean temperature was similar to that predicted for the next century and atmospheric carbon dioxide concentrations were slightly higher. Sea level was also higher than today, implying a reduction in the extent of the ice sheets. Thus, the mid-Pliocene Warm Period provides a unique testing ground to investigate the stability of the Earth's ice sheets and their contribution to sea level in a warmer-than-modern world. Climate models and ice sheet models can be used to enhance our understanding of ice sheet stability, however, uncertainties associated with different ice-sheet modelling frameworks/approaches mean that a rigorous comparison of numerical ice sheet model simulations for the Pliocene is essential. As an extension to the Pliocene Model Intercomparison Project (PlioMIP; Haywood et al., 2010, 2011a), the Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP) will address these uncertainties. Here we outline the PLISMIP experimental design and initialisation conditions that have been adopted to simulate the Greenland and Antarctic ice sheets under present day and warm mid-Pliocene conditions. Not only will this project provide a new benchmark in the simulation of ice sheets in a past warm period, but the analysis of model sensitivity to various uncertainties could directly inform future predictions of ice sheet and sea level change.

scholarly journals Simulating the Antarctic ice sheet in the Late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project

2014 ◽  
Vol 8 (6) ◽  
pp. 5539-5588 ◽  
Author(s):  
B. de Boer ◽  
A. M. Dolan ◽  
J. Bernales ◽  
E. Gasson ◽  
H. Goelzer ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Warm Period ◽  
Antarctic Ice Sheet ◽  
Late Pliocene ◽  
Bedrock Topography ◽  
Intercomparison Project ◽  
The Antarctic

Abstract. In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The Late-Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of four sensitivity experiments. Ice-sheet model forcing fields are taken from the HadCM3 atmosphere–ocean climate model runs for the pre-industrial and the Pliocene. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, although the models are setup with their own parameter settings. For the Pliocene simulations using the Bedmap1 bedrock topography, some models show a small retreat of the East Antarctic ice sheet, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. This can be ascribed to either the surface mass balance, as the HadCM3 Pliocene climate shows a significant increase over the Wilkes and Aurora basin, or the initial bedrock topography. For the latter, our simulations with the recently published Bedmap2 bedrock topography indicate a significantly larger contribution to Pliocene sea-level rise from the East Antarctic ice sheet for all six models relative to the simulations with Bedmap1.

scholarly journals Ice Sheet Model Intercomparison Project (ISMIP6) contribution to CMIP6

2016 ◽  
Vol 9 (12) ◽  
pp. 4521-4545 ◽  
Author(s):  
Sophie M. J. Nowicki ◽  
Anthony Payne ◽  
Eric Larour ◽  
Helene Seroussi ◽  
Heiko Goelzer ◽  
...  
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Coupled Model ◽  
Sea Level Change ◽  
Model Intercomparison ◽  
Sea Level Changes ◽  
Level Change ◽  
Intercomparison Project

Abstract. Reducing the uncertainty in the past, present, and future contribution of ice sheets to sea-level change requires a coordinated effort between the climate and glaciology communities. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is the primary activity within the Coupled Model Intercomparison Project – phase 6 (CMIP6) focusing on the Greenland and Antarctic ice sheets. In this paper, we describe the framework for ISMIP6 and its relationship with other activities within CMIP6. The ISMIP6 experimental design relies on CMIP6 climate models and includes, for the first time within CMIP, coupled ice-sheet–climate models as well as standalone ice-sheet models. To facilitate analysis of the multi-model ensemble and to generate a set of standard climate inputs for standalone ice-sheet models, ISMIP6 defines a protocol for all variables related to ice sheets. ISMIP6 will provide a basis for investigating the feedbacks, impacts, and sea-level changes associated with dynamic ice sheets and for quantifying the uncertainty in ice-sheet-sourced global sea-level change.

scholarly journals Greater Greenland Ice Sheet contribution to global sea level rise in CMIP6

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Stefan Hofer ◽  
Charlotte Lang ◽  
Charles Amory ◽  
Christoph Kittel ◽  
Alison Delhasse ◽  
...  
Keyword(s):  
Mass Loss ◽  
Sea Level Rise ◽  
Sea Level ◽  
Climate Models ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Cmip5 Models ◽  
Climate Projections ◽  
The Impact

AbstractFuture climate projections show a marked increase in Greenland Ice Sheet (GrIS) runoff during the 21st century, a direct consequence of the Polar Amplification signal. Regional climate models (RCMs) are a widely used tool to downscale ensembles of projections from global climate models (GCMs) to assess the impact of global warming on GrIS melt and sea level rise contribution. Initial results of the CMIP6 GCM model intercomparison project have revealed a greater 21st century temperature rise than in CMIP5 models. However, so far very little is known about the subsequent impacts on the future GrIS surface melt and therefore sea level rise contribution. Here, we show that the total GrIS sea level rise contribution from surface mass loss in our high-resolution (15 km) regional climate projections is 17.8  ±  7.8 cm in SSP585, 7.9 cm more than in our RCP8.5 simulations using CMIP5 input. We identify a +1.3 °C greater Arctic Amplification and associated cloud and sea ice feedbacks in the CMIP6 SSP585 scenario as the main drivers. Additionally, an assessment of the GrIS sea level contribution across all emission scenarios highlights, that the GrIS mass loss in CMIP6 is equivalent to a CMIP5 scenario with twice the global radiative forcing.

scholarly journals Simulation of the Greenland Ice Sheet over two glacial–interglacial cycles: investigating a sub-ice- shelf melt parameterization and relative sea level forcing in an ice-sheet–ice-shelf model

2018 ◽  
Vol 14 (5) ◽  
pp. 619-635 ◽  
Author(s):  
Sarah L. Bradley ◽  
Thomas J. Reerink ◽  
Roderik S. W. van de Wal ◽  
Michiel M. Helsen
Keyword(s):  
Continental Shelf ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Shelf ◽  
Temporal Behaviour ◽  
Ice Shelves ◽  
Non Local ◽  
Continental Shelf Break

Abstract. Observational evidence, including offshore moraines and sediment cores, confirm that at the Last Glacial Maximum (LGM) the Greenland ice sheet (GrIS) expanded to a significantly larger spatial extent than seen at present, grounding into Baffin Bay and out onto the continental shelf break. Given this larger spatial extent and its close proximity to the neighbouring Laurentide Ice Sheet (LIS) and Innuitian Ice Sheet (IIS), it is likely these ice sheets will have had a strong non-local influence on the spatial and temporal behaviour of the GrIS. Most previous paleo ice-sheet modelling simulations recreated an ice sheet that either did not extend out onto the continental shelf or utilized a simplified marine ice parameterization which did not fully include the effect of ice shelves or neglected the sensitivity of the GrIS to this non-local bedrock signal from the surrounding ice sheets. In this paper, we investigated the evolution of the GrIS over the two most recent glacial–interglacial cycles (240 ka BP to the present day) using the ice-sheet–ice-shelf model IMAU-ICE. We investigated the solid earth influence of the LIS and IIS via an offline relative sea level (RSL) forcing generated by a glacial isostatic adjustment (GIA) model. The RSL forcing governed the spatial and temporal pattern of sub-ice-shelf melting via changes in the water depth below the ice shelves. In the ensemble of simulations, at the glacial maximums, the GrIS coalesced with the IIS to the north and expanded to the continental shelf break to the southwest but remained too restricted to the northeast. In terms of the global mean sea level contribution, at the Last Interglacial (LIG) and LGM the ice sheet added 1.46 and −2.59 m, respectively. This LGM contribution by the GrIS is considerably higher (∼ 1.26 m) than most previous studies whereas the contribution to the LIG highstand is lower (∼ 0.7 m). The spatial and temporal behaviour of the northern margin was highly variable in all simulations, controlled by the sub-ice-shelf melting which was dictated by the RSL forcing and the glacial history of the IIS and LIS. In contrast, the southwestern part of the ice sheet was insensitive to these forcings, with a uniform response in all simulations controlled by the surface air temperature, derived from ice cores.

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