Briefing: Antarctic ice sheet mass loss and future sea-level rise

Emerging evidence suggests retreat of the Antarctic Ice Sheet (AIS) can persist considerably longer than the duration of the forcing. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and responses on century and longer timescales. New data from Iceberg Alley identifies eight retreat phases after the last Ice Age that de-stabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently stabilized equally rapidly. New blue ice records and independent ice-sheet modeling demonstrate the dynamic response of the AIS included a step-wise retreat of up to 400&#160;km across the Ross Sea, accompanied by ice elevation drawdown of the West Antarctic Ice Sheet (>600&#160;m). Together, these long time series support studies that propose the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat, associated with substantial global sea level rise.

Download Full-text

A high-end sea level rise probabilistic projection including rapid Antarctic ice sheet mass loss

Environmental Research Letters ◽

10.1088/1748-9326/aa6512 ◽

2017 ◽

Vol 12 (4) ◽

pp. 044013 ◽

Cited By ~ 61

Author(s):

Dewi Le Bars ◽

Sybren Drijfhout ◽

Hylke de Vries

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

Probabilistic Projection

Download Full-text

Acceleration of Dynamic Ice Loss in Antarctica From Satellite Gravimetry

Frontiers in Earth Science ◽

10.3389/feart.2021.741789 ◽

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.

Download Full-text

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

10.5194/egusphere-egu2020-12835 ◽

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

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.&#160; 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).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.

Download Full-text

Antarctic ice sheet response to upper-bound scenarios

10.5194/egusphere-egu21-11823 ◽

2021 ◽

Author(s):

Sainan Sun ◽

Frank Pattyn

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Upper Bound ◽

Ice Sheet ◽

Climate Forcing ◽

Ice Shelf ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

Basal Sliding ◽

The Antarctic

Mass loss of the Antarctic ice sheet contributes the largest uncertainty of future sea-level rise projections. Ice-sheet model predictions are limited by uncertainties in climate forcing and poor understanding of processes such as ice viscosity. The Antarctic BUttressing Model Intercomparison Project (ABUMIP) has investigated the 'end-member' scenario, i.e., a total and sustained removal of buttressing from all Antarctic ice shelves, which can be regarded as the upper-bound physical possible, but implausible contribution of sea-level rise due to ice-shelf loss. In this study, we add successive layers of &#8216;realism&#8217; to the ABUMIP scenario by considering sustained regional ice-shelf collapse and by introducing ice-shelf regrowth after collapse with the inclusion of ice-sheet and ice-shelf damage (Sun et al., 2017). Ice shelf regrowth has the ability to stabilize grounding lines, while ice shelf damage may reinforce ice loss. In combination with uncertainties from basal sliding and ice rheology, a more realistic physical upperbound to ice loss is sought. Results are compared in the light of other proposed mechanisms, such as MICI due to ice cliff collapse.

Download Full-text

Antarctic Ice-Sheet Volume at 18000 Years B.P. and Holocene Sea-Level Changes at the West Antarctic Margin

Journal of Glaciology ◽

10.3189/s0022143000014751 ◽

1979 ◽

Vol 24 (90) ◽

pp. 213-230 ◽

Cited By ~ 1

Author(s):

Craig S. Lingle ◽

James A. Clark

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Sea Level Changes ◽

Ice Shelf ◽

Relative Sea Level ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

The Antarctic

AbstractThe Antarctic ice sheet has been reconstructed at 18000 years b.p. by Hughes and others (in press) using an ice-flow model. The volume of the portion of this reconstruction which contributed to a rise of post-glacial eustatic sea-level has been calculated and found to be (9.8±1.5) × 106 km3. This volume is equivalent to 25±4 m of eustatic sea-level rise, defined as the volume of water added to the ocean divided by ocean area. The total volume of the reconstructed Antarctic ice sheet was found to be (37±6) × 106 km3. If the results of Hughes and others are correct, Antarctica was the second largest contributor to post-glacial eustatic sea-level rise after the Laurentide ice sheet. The Farrell and Clark (1976) model for computation of the relative sea-level changes caused by changes in ice and water loading on a visco-elastic Earth has been applied to the ice-sheet reconstruction, and the results have been combined with the changes in relative sea-level caused by Northern Hemisphere deglaciation as previously calculated by Clark and others (1978). Three families of curves have been compiled, showing calculated relative sea-level change at different times near the margin of the possibly unstable West Antarctic ice sheet in the Ross Sea, Pine Island Bay, and the Weddell Sea. The curves suggest that the West Antarctic ice sheet remained grounded to the edge of the continental shelf until c. 13000 years b.p., when the rate of sea-level rise due to northern ice disintegration became sufficient to dominate emergence near the margin predicted otherwise to have been caused by shrinkage of the Antarctic ice mass. In addition, the curves suggest that falling relative sea-levels played a significant role in slowing and, perhaps, reversing retreat when grounding lines approached their present positions in the Ross and Weddell Seas. A predicted fall of relative sea-level beneath the central Ross Ice Shelf of as much as 23 m during the past 2000 years is found to be compatible with recent field evidence that the ice shelf is thickening in the south-east quadrant.

Download Full-text

Decadal-scale onset and termination of Antarctic ice-mass loss during the last deglaciation

Nature Communications ◽

10.1038/s41467-021-27053-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Michael E. Weber ◽

Nicholas R. Golledge ◽

Chris J. Fogwill ◽

Chris S. M. Turney ◽

Zoë A. Thomas

Keyword(s):

Mass Loss ◽

Sea Level Rise ◽

Sea Level ◽

Ross Sea ◽

Ice Sheet ◽

Rate Of Change ◽

Last Deglaciation ◽

Decadal Scale ◽

Ice Sheet Modeling ◽

Global Sea Level

AbstractEmerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and timescale of responses. Iceberg-rafted debris data from Iceberg Alley identify eight retreat phases after the Last Glacial Maximum that each destabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently re-stabilized equally rapidly. This dynamic response of the AIS is supported by (i) a West Antarctic blue ice record of ice-elevation drawdown >600 m during three such retreat events related to globally recognized deglacial meltwater pulses, (ii) step-wise retreat up to 400 km across the Ross Sea shelf, (iii) independent ice sheet modeling, and (iv) tipping point analysis. Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.

Download Full-text

Impact of transient increases in atmospheric CO2 on the accumulation and mass balance of the Antarctic ice sheet

Annals of Glaciology ◽

10.1017/s0260305500013938 ◽

1997 ◽

Vol 25 ◽

pp. 137-144 ◽

Cited By ~ 6

Author(s):

Siobhan P. O’Farrell ◽

John L. McGregor ◽

Leon D. Rotstayn ◽

William F. Budd ◽

Christopher Zweck ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Coupled Model ◽

Negative Contribution ◽

Antarctic Ice Sheet ◽

Ice Shelves ◽

Basal Melting ◽

Main Effects ◽

The Antarctic

The response of the Antarctic ice sheet to climate change over the next 500 years is calculated using the output of a transient-coupled ocean-atmosphere simulation assuming the atmospheric CO2value increases up to three times present levels. The main effects on the ice sheet on this time-scale include increasing rates of accumulation, minimal surface melting, and basal melting of ice shelves. A semi-Lagrangian transport scheme for moisture was used to improve the model’s ability to represent realistic rates of accumulation under present-day conditions, and thereby increase confidence in the anomalies calculated under a warmer climate. The response of the Antarctic ice sheet to the warming is increased accumulation inland, offset by loss from basal melting from the floating ice, and increased ice flow near the grounding line. The preliminary results of this study show that the change to the ice-sheet balance for the transient-coupled model forcing amounted to a minimal sea-level contribution in the next century, but a net positive sea-level rise of 0.21 m by 500 years. This new result supercedes earlier results that showed the Antarctic ice sheet made a net negative contribution to sea-level rise over the next century. However, the amplitude of the sea-level rise is still dominated In the much larger contributions expected from thermal expansion of the ocean of 0.25 m for 100 years and 1.00 m for 500 years.

Download Full-text

Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet

Science Advances ◽

10.1126/sciadv.1500589 ◽

2015 ◽

Vol 1 (8) ◽

pp. e1500589 ◽

Cited By ~ 59

Author(s):

Ricarda Winkelmann ◽

Anders Levermann ◽

Andy Ridgwell ◽

Ken Caldeira

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Carbon Emissions ◽

Fossil Fuel ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Global Sea Level ◽

The Antarctic

The Antarctic Ice Sheet stores water equivalent to 58 m in global sea-level rise. We show in simulations using the Parallel Ice Sheet Model that burning the currently attainable fossil fuel resources is sufficient to eliminate the ice sheet. With cumulative fossil fuel emissions of 10,000 gigatonnes of carbon (GtC), Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 m per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice Sheet becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West and East Antarctica results in a threshold increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice Sheet in its entirety with associated sea-level rise that far exceeds that of all other possible sources.

Download Full-text

The contribution of the East Antarctic Ice Sheet to future sea level rise

10.5194/egusphere-egu2020-3099 ◽

2020 ◽

Author(s):

Jim Jordan ◽

Hilmar Gudmundsson ◽

Adrian Jenkins ◽

Chris Stokes ◽

Stewart Jamieson ◽

...

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Ice Sheet ◽

Ice Shelf ◽

Antarctic Ice Sheet ◽

Mean Sea Level ◽

Potential Contributor ◽

Global Mean Sea Level ◽

Global Mean ◽

East Antarctic Ice Sheet

The East Antarctic Ice Sheet (EAIS) is the single largest potential contributor to future global mean sea level rise, containing a water mass equivalent of 53 m. Recent work has found the overall mass balance of the EAIS to be approximately in equilibrium, albeit with large uncertainties. However, changes in oceanic conditions have the potential to upset this balance. This could happen by both a general warming of the ocean and also by shifts in oceanic conditions allowing warmer water masses to intrude into ice shelf cavities.We use the &#218;a numerical ice-flow model, combined with ocean-melt rates parameterized by the PICO box mode, to predict the future contribution to global-mean sea level of the EAIS. Results are shown for the next 100 years under a range of emission scenarios and oceanic conditions on a region by region basis, as well as for the whole of the EAIS.&#160;

Download Full-text