Antarctic Ice Sheet mass balance over the past decade from 2005 to 2016

2020 ◽  
Author(s):  
Yijing Lin
Keyword(s):  
Global Warming ◽  
Mass Loss ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Grounding Line ◽  
Ice Sheet Mass Balance ◽  
The Antarctic

<p>Global warming has become a world concerned issue which draws increasingly attention of the scientific community. Sea-level rise is an important indicator of Global warming as it integrates many factors of climate change including ice sheet melting.  The accurate assessment of the Antarctic ice sheet mass balance is applied to deeply explore the impact of minor change in Antarctic ice sheet on sea level rise. Based on multi-source remote sensing product, we finely estimated the mass balance of the Antarctic ice sheet and discussed dynamics and climatological causes of the fluctuations from 2005 to 2015 by IOM (Input-Output-Method).</p><p>In our study, the calculation method of ice flux on the grounding line is improved. We also precisely evaluate the ice flux as an output component. The result shows that: (1) The Antarctic ice sheet was continuously losing mass during the period of 2005-2016. (2) The mass loss of the Antarctic ice sheet was dominated by West Antarctica when East Antarctica was in a positive mass balance, but some basins also occurred significant mass loss. The Antarctic peninsula fluctuated in a state of zero balance. (3) The change in the mass balance of the ice sheet was dominated by the surface mass balance as a whole, and was mainly affected by the interannual variation of climatological factors. From a small-scale perspective, ice shelf thinning and glacier calving causes the change of ice flux on the grounding line. That change leads to the severe mass loss in the region it happened. Therefore the mass loss in the year of the disintegration event happened increases.</p>

scholarly journals The effect of overshooting 1.5 °C global warming on the mass loss of the Greenland ice sheet

2018 ◽  
Vol 9 (4) ◽  
pp. 1169-1189 ◽  
Author(s):  
Martin Rückamp ◽  
Ulrike Falk ◽  
Katja Frieler ◽  
Stefan Lange ◽  
Angelika Humbert
Keyword(s):  
Global Warming ◽  
Mass Loss ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. Sea-level rise associated with changing climate is expected to pose a major challenge for societies. Based on the efforts of COP21 to limit global warming to 2.0 ∘C or even 1.5 ∘C by the end of the 21st century (Paris Agreement), we simulate the future contribution of the Greenland ice sheet (GrIS) to sea-level change under the low emission Representative Concentration Pathway (RCP) 2.6 scenario. The Ice Sheet System Model (ISSM) with higher-order approximation is used and initialized with a hybrid approach of spin-up and data assimilation. For three general circulation models (GCMs: HadGEM2-ES, IPSL-CM5A-LR, MIROC5) the projections are conducted up to 2300 with forcing fields for surface mass balance (SMB) and ice surface temperature (Ts) computed by the surface energy balance model of intermediate complexity (SEMIC). The projected sea-level rise ranges between 21–38 mm by 2100 and 36–85 mm by 2300. According to the three GCMs used, global warming will exceed 1.5 ∘C early in the 21st century. The RCP2.6 peak and decline scenario is therefore manually adjusted in another set of experiments to suppress the 1.5 ∘C overshooting effect. These scenarios show a sea-level contribution that is on average about 38 % and 31 % less by 2100 and 2300, respectively. For some experiments, the rate of mass loss in the 23rd century does not exclude a stable ice sheet in the future. This is due to a spatially integrated SMB that remains positive and reaches values similar to the present day in the latter half of the simulation period. Although the mean SMB is reduced in the warmer climate, a future steady-state ice sheet with lower surface elevation and hence volume might be possible. Our results indicate that uncertainties in the projections stem from the underlying GCM climate data used to calculate the surface mass balance. However, the RCP2.6 scenario will lead to significant changes in the GrIS, including elevation changes of up to 100 m. The sea-level contribution estimated in this study may serve as a lower bound for the RCP2.6 scenario, as the currently observed sea-level rise is not reached in any of the experiments; this is attributed to processes (e.g. ocean forcing) not yet represented by the model, but proven to play a major role in GrIS mass loss.

scholarly journals ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21<sup>st</sup> century

2020 ◽  
Author(s):  
Helene Seroussi ◽  
Sophie Nowicki ◽  
Antony J. Payne ◽  
Heiko Goelzer ◽  
William H. Lipscomb ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
The Antarctic

Abstract. 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 Coupled 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 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 conditions, with limited mass gain in East Antarctica.

Decreasing Antarctic surface mass balance due to runoff-dominated ablation by 2100

2020 ◽  
Author(s):  
Christoph Kittel ◽  
Charles Amory ◽  
Cécile Agosta ◽  
Nicolas Jourdain ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
Ice Shelves ◽  
The Antarctic

&lt;p&gt;&lt;span&gt;The surface mass balance (SMB) of the Antarctic ice sheet is often considered as a negative contributor to the sea level rise as present snowfall accumulation largely compensate&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; for ablation through wind erosion, sublimation and runoff. The latter is even almost negligible since current Antarctic surface melting is limited to relatively scarce events over generally peripheral areas and refreezes almost entirely into the snowpack. However, melting can significantly affect the stability of ice shelves through hydrofracturing, potentially leading to their disintegration, acceleration of grounded ice and increased sea level rise. Although a large increase in snowfall is expected in a warmer climate, more numerous and stronger melting events could conversely lead to a larger risk of ice shelf collapse. In this study, we provide an estimation of the SMB of the Antarctic ice sheet for the end of the 21st&amp;#160;century by forcing the state-of-the-art regional climate model MAR with three different global climate models. We chose the models (from both the Coupled Model Intercomparison Project Phase 5 and 6 - CMIP5 and CMIP6) providing the best metrics for representing the current Antarctic climate. While the increase in snowfall largely compensates snow ablation through runoff in CMIP5-forced projections, CMIP6-forced simulations reveal that runoff cannot be neglected in the future as it accounts for a maximum of 50% of snowfall and becomes the main ablation component over the ice sheet. Furthermore, we identify a tipping point (ie., a warming of 4&amp;#176;C) at which the Antarctic SMB starts to decrease as a result of enhanced runoff particularly over ice shelves. Our results highlight the importance of taking into account meltwater production and runoff and indicate that previous model studies neglecting these processes yield overestimated SMB estimates, ultimately leading to underestimated Antarctic contribution to sea level rise. Finally, melt rates over each ice shelf are higher than those that led to the collapse of the Larsen A and B ice shelves, suggesting a high probability of ice shelf collapses all over peripheral Antarctica by 2100.&lt;/span&gt;&lt;/p&gt;

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

2020 ◽  
Author(s):  
Helene Seroussi ◽  
Heiko Goelzer ◽  
Mathieu Morlighem ◽  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
East Antarctica ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
The Antarctic

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to differ- ent 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 Coupled 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 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 conditions, with limited mass gain in East Antarctica.&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

scholarly journals The GRISLI-LSCE contribution to ISMIP6, Part 2: projections of the Antarctic ice sheet evolution by the end of the 21<sup>st</sup> century

2020 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Greenhouse Gas Emission ◽  
Ice Sheet ◽  
Companion Paper ◽  
Antarctic Ice Sheet ◽  
Grounding Line ◽  
Common Framework ◽  
Global Sea Level ◽  
The Antarctic

Abstract. Of primary societal importance, the ice sheet contribution to global sea level rise over the 21st century remains largely uncertain. In particular, the contribution of the Antarctic ice sheet by 2100 ranges from a few millimetres to more than one metre in the recent literature. The Ice Sheet Model Intercomparison Project for CMIP6 aimed at reducing the uncertainties on the fate of the ice sheets in the future by gathering various ice sheet models in a common framework. While in a companion paper we present the GRISLI-LSCE contribution to ISMIP6-Greenland, we present here the GRISLI-LSCE contribution to ISMIP6-Antarctica. We show that our model is strongly sensitive to the climate forcing used, with a contribution of the Antarctic ice sheet to global sea level rise by 2100 that ranges from −50 mm to +150 mm of sea level equivalent. Future oceanic warming leads to a decrease in thickness of the ice shelves and implies grounding line retreats while increased precipitation partially mitigates the ice sheet contribution to global sea level rise. Most of ice sheet changes over the next century are dampened under low greenhouse gas emission scenarios. Uncertainties related to sub-shelf basal melt induce large differences in simulated grounding line retreats, confirming the importance of this process and its representation in ice sheet models for the projections of the Antarctic ice sheet.

scholarly journals Acceleration of Dynamic Ice Loss in Antarctica From Satellite Gravimetry

2021 ◽  
Vol 9 ◽  
Author(s):  
Theresa Diener ◽  
Ingo Sasgen ◽  
Cécile Agosta ◽  
Johannes J. Fürst ◽  
Matthias H. Braun ◽  
...  
Keyword(s):  
Mass Loss ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
Surface Ice ◽  
The Antarctic ◽  
Dynamic Discharge

The dynamic stability of the Antarctic Ice Sheet is one of the largest uncertainties in projections of future global sea-level rise. Essential for improving projections of the ice sheet evolution is the understanding of the ongoing trends and accelerations of mass loss in the context of ice dynamics. Here, we examine accelerations of mass change of the Antarctic Ice Sheet from 2002 to 2020 using data from the GRACE (Gravity Recovery and Climate Experiment; 2002–2017) and its follow-on GRACE-FO (2018-present) satellite missions. By subtracting estimates of net snow accumulation provided by re-analysis data and regional climate models from GRACE/GRACE-FO mass changes, we isolate variations in ice-dynamic discharge and compare them to direct measurements based on the remote sensing of the surface-ice velocity (2002–2017). We show that variations in the GRACE/GRACE-FO time series are modulated by variations in regional snow accumulation caused by large-scale atmospheric circulation. We show for the first time that, after removal of these surface effects, accelerations of ice-dynamic discharge from GRACE/GRACE-FO agree well with those independently derived from surface-ice velocities. For 2002–2020, we recover a discharge acceleration of -5.3 ± 2.2 Gt yr−2 for the entire ice sheet; these increasing losses originate mainly in the Amundsen and Bellingshausen Sea Embayment regions (68%), with additional significant contributions from Dronning Maud Land (18%) and the Filchner-Ronne Ice Shelf region (13%). Under the assumption that the recovered rates and accelerations of mass loss persisted independent of any external forcing, Antarctica would contribute 7.6 ± 2.9 cm to global mean sea-level rise by the year 2100, more than two times the amount of 2.9 ± 0.6 cm obtained by linear extrapolation of current GRACE/GRACE-FO mass loss trends.

scholarly journals Four decades of Antarctic Ice Sheet mass balance from 1979–2017

2019 ◽  
Vol 116 (4) ◽  
pp. 1095-1103 ◽  
Author(s):  
Eric Rignot ◽  
Jérémie Mouginot ◽  
Bernd Scheuchl ◽  
Michiel van den Broeke ◽  
Melchior J. van Wessem ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Ice Sheet ◽  
East Antarctica ◽  
Balance Model ◽  
West Antarctica ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
Ice Sheet Mass Balance

We use updated drainage inventory, ice thickness, and ice velocity data to calculate the grounding line ice discharge of 176 basins draining the Antarctic Ice Sheet from 1979 to 2017. We compare the results with a surface mass balance model to deduce the ice sheet mass balance. The total mass loss increased from 40 ± 9 Gt/y in 1979–1990 to 50 ± 14 Gt/y in 1989–2000, 166 ± 18 Gt/y in 1999–2009, and 252 ± 26 Gt/y in 2009–2017. In 2009–2017, the mass loss was dominated by the Amundsen/Bellingshausen Sea sectors, in West Antarctica (159 ± 8 Gt/y), Wilkes Land, in East Antarctica (51 ± 13 Gt/y), and West and Northeast Peninsula (42 ± 5 Gt/y). The contribution to sea-level rise from Antarctica averaged 3.6 ± 0.5 mm per decade with a cumulative 14.0 ± 2.0 mm since 1979, including 6.9 ± 0.6 mm from West Antarctica, 4.4 ± 0.9 mm from East Antarctica, and 2.5 ± 0.4 mm from the Peninsula (i.e., East Antarctica is a major participant in the mass loss). During the entire period, the mass loss concentrated in areas closest to warm, salty, subsurface, circumpolar deep water (CDW), that is, consistent with enhanced polar westerlies pushing CDW toward Antarctica to melt its floating ice shelves, destabilize the glaciers, and raise sea level.

scholarly journals The GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 2: Projections of the Antarctic ice sheet evolution by the end of the 21st century

2021 ◽  
Vol 15 (2) ◽  
pp. 1031-1052
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Coupled Model ◽  
Model Intercomparison ◽  
Antarctic Ice Sheet ◽  
Grounding Line ◽  
Intercomparison Project ◽  
Global Sea Level ◽  
The Antarctic

Abstract. The Antarctic ice sheet's contribution to global sea level rise over the 21st century is of primary societal importance and remains largely uncertain as of yet. In particular, in the recent literature, the contribution of the Antarctic ice sheet by 2100 can be negative (sea level fall) by a few centimetres or positive (sea level rise), with some estimates above 1 m. The Ice Sheet Model Intercomparison Project for the Coupled Model Intercomparison Project – phase 6 (ISMIP6) aimed at reducing the uncertainties in the fate of the ice sheets in the future by gathering various ice sheet models in a common framework. Here, we present the GRISLI-LSCE (Grenoble Ice Sheet and Land Ice model of the Laboratoire des Sciences du Climat et de l'Environnement) contribution to ISMIP6-Antarctica. We show that our model is strongly sensitive to the climate forcing used, with a contribution of the Antarctic ice sheet to global sea level rise by 2100 that ranges from −50 to +150 mm sea level equivalent (SLE). Future oceanic warming leads to a decrease in thickness of the ice shelves, resulting in grounding-line retreat, while increased surface mass balance partially mitigates or even overcompensates the dynamic ice sheet contribution to global sea level rise. Most of the ice sheet changes over the next century are dampened under low-greenhouse-gas-emission scenarios. Uncertainties related to sub-ice-shelf melt rates induce large differences in simulated grounding-line retreat, confirming the importance of this process and its representation in ice sheet models for projections of the Antarctic ice sheet's evolution.

scholarly journals Monitoring southwest Greenland’s ice sheet melt with ambient seismic noise

2016 ◽  
Vol 2 (5) ◽  
pp. e1501538 ◽  
Author(s):  
Aurélien Mordret ◽  
T. Dylan Mikesell ◽  
Christopher Harig ◽  
Bradley P. Lipovsky ◽  
Germán A. Prieto
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Seismic Noise ◽  
Seismic Velocity ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sea Level Changes ◽  
Ice Sheet Mass Balance ◽  
Velocity Changes

The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth’s crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations.

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