scholarly journals The tipping points and early-warning indicators for Pine Island Glacier, West Antarctica

2020 ◽  
Author(s):  
Sebastian H. R. Rosier ◽  
Ronja Reese ◽  
Jonathan F. Donges ◽  
Jan De Rydt ◽  
G. Hilmar Gudmundsson ◽  
...  
Keyword(s):  
Mass Loss ◽  
Early Warning ◽  
Ice Sheet ◽  
Systematic Investigation ◽  
Critical Threshold ◽  
Tipping Points ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Early Warning Indicators ◽  
Warning Indicators

Abstract. Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to this is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice-internal dynamics can drive a self-amplifying retreat committing a glacier to irreversible, rapid and substantial ice loss. This process might have already been triggered in the Amundsen Sea region, where Pine Island and Thwaites glaciers dominate the current mass loss from Antarctica, but modelling and observational techniques have not been able to establish this rigorously, leading to divergent views on the future mass loss of the WAIS. Here, we aim at closing this knowledge gap by conducting a systematic investigation of the stability regime of Pine Island Glacier. To this end we show that early warning indicators robustly detect critical slowing for the marine ice sheet instability. We are thereby able to identify three distinct tipping points in response to increases in ocean-induced melt. The third and final event, triggered by an ocean warming of approximately 1.2 °C from the steady state model configuration, leads to a retreat of the entire glacier that could initiate a collapse of the West Antarctic Ice Sheet.

scholarly journals The tipping points and early warning indicators for Pine Island Glacier, West Antarctica

2021 ◽  
Vol 15 (3) ◽  
pp. 1501-1516
Author(s):  
Sebastian H. R. Rosier ◽  
Ronja Reese ◽  
Jonathan F. Donges ◽  
Jan De Rydt ◽  
G. Hilmar Gudmundsson ◽  
...  
Keyword(s):  
Mass Loss ◽  
Early Warning ◽  
Ice Sheet ◽  
Tipping Points ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Early Warning Indicators ◽  
Warning Indicators

Abstract. Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to ongoing and future changes is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice internal dynamics can drive a self-sustaining retreat committing a glacier to irreversible, rapid and substantial ice loss. This process might have already been triggered in the Amundsen Sea region, where Pine Island and Thwaites glaciers dominate the current mass loss from Antarctica, but modelling and observational techniques have not been able to establish this rigorously, leading to divergent views on the future mass loss of the West Antarctic Ice Sheet. Here, we aim at closing this knowledge gap by conducting a systematic investigation of the stability regime of Pine Island Glacier. To this end we show that early warning indicators in model simulations robustly detect the onset of the marine ice sheet instability. We are thereby able to identify three distinct tipping points in response to increases in ocean-induced melt. The third and final event, triggered by an ocean warming of approximately 1.2 ∘C from the steady-state model configuration, leads to a retreat of the entire glacier that could initiate a collapse of the West Antarctic Ice Sheet.

The tipping points of Pine Island Glacier, West Antarctica

2020 ◽  
Author(s):  
Sebastian Rosier ◽  
Ronja Reese ◽  
Jonathan Donges ◽  
Jan De Rydt ◽  
Hilmar Gudmundsson ◽  
...  
Keyword(s):  
Mass Loss ◽  
Ice Sheet ◽  
Tipping Point ◽  
Critical Threshold ◽  
Tipping Points ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

<p><strong>Mass loss from the Antarctic Ice Sheet is the main source of uncertainty in projections of future sea-level rise, with important implications for coastal regions worldwide. Central to this is the marine ice sheet instability: once a critical threshold, or tipping point, is crossed, ice-internal dynamics can drive a self-amplifying retreat committing a glacier to substantial ice loss that is irreversible at time scales most relevant to human societies. This process might have already been triggered in the Amundsen Sea region, where Pine Island and Thwaites glaciers dominate the current mass loss from Antarctica. However, current modelling and observational techniques have not been able to establish this rigorously, leading to divergent views on the future mass loss of the West Antarctic Ice Sheet. Here we aim at closing this knowledge gap by conducting a systematic investigation of the tipping points of Pine Island Glacier using established early warning indicators that detect critical slowing as a system approaches a tipping point. We are thereby able to identify three distinct tipping points in response to increases in ocean-induced melt. The third and final event, triggered for less than a tripling of melt rates, leads to a retreat of the entire glacier that could initiate a collapse of the West Antarctic Ice Sheet.</strong></p>

scholarly journals Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

2018 ◽  
Vol 12 (2) ◽  
pp. 521-547 ◽  
Author(s):  
Alex S. Gardner ◽  
Geir Moholdt ◽  
Ted Scambos ◽  
Mark Fahnstock ◽  
Stefan Ligtenberg ◽  
...  
Keyword(s):  
Mass Loss ◽  
Average Rate ◽  
Ice Sheet ◽  
Snow Accumulation ◽  
Amundsen Sea ◽  
Ice Flow ◽  
Antarctic Ice Sheet ◽  
Modest Increase ◽  
The Past ◽  
West Antarctic

Abstract. Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013–2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ∼ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of < 10 m yr−1, resulting from multiple overlapping image pairs acquired during the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr−1) in 2015, an increase of 36 ± 15 Gt yr−1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr−1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

Local Facilitation May Cause Tipping Points on a Landscape Level Preceded by Early-Warning Indicators

2015 ◽  
Vol 186 (4) ◽  
pp. E81-E90 ◽  
Author(s):  
Chi Xu ◽  
Egbert H. Van Nes ◽  
Milena Holmgren ◽  
Sonia Kéfi ◽  
Marten Scheffer
Keyword(s):  
Early Warning ◽  
Tipping Points ◽  
Early Warning Indicators ◽  
Warning Indicators ◽  
Landscape Level

scholarly journals The tipping points and early-warning indicators for Pine Island Glacier, West Antarctica

2020 ◽  
Author(s):  
Sebastian Rosier ◽  
Ronja Reese ◽  
Jonathan Donges ◽  
Jan De Rydt ◽  
G. Gudmundsson ◽  
...  
Keyword(s):  
Early Warning ◽  
Tipping Points ◽  
West Antarctica ◽  
Early Warning Indicators ◽  
Warning Indicators

scholarly journals A Joint Inversion Estimate of Antarctic Ice Sheet Mass Balance Using Multi-Geodetic Data Sets

2019 ◽  
Vol 11 (6) ◽  
pp. 653 ◽  
Author(s):  
Chunchun Gao ◽  
Yang Lu ◽  
Zizhan Zhang ◽  
Hongling Shi
Keyword(s):  
Mass Balance ◽  
Joint Inversion ◽  
Ice Sheet ◽  
Mass Change ◽  
West Antarctica ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
Uplift Rates ◽  
The Antarctic

Many recent mass balance estimates using the Gravity Recovery and Climate Experiment (GRACE) and satellite altimetry (including two kinds of sensors of radar and laser) show that the ice mass of the Antarctic ice sheet (AIS) is in overall decline. However, there are still large differences among previously published estimates of the total mass change, even in the same observed periods. The considerable error sources mainly arise from the forward models (e.g., glacial isostatic adjustment [GIA] and firn compaction) that may be uncertain but indispensable to simulate some processes not directly measured or obtained by these observations. To minimize the use of these forward models, we estimate the mass change of ice sheet and present-day GIA using multi-geodetic observations, including GRACE and Ice, Cloud and land Elevation Satellite (ICESat), as well as Global Positioning System (GPS), by an improved method of joint inversion estimate (JIE), which enables us to solve simultaneously for the Antarctic GIA and ice mass trends. The GIA uplift rates generated from our JIE method show a good agreement with the elastic-corrected GPS uplift rates, and the total GIA-induced mass change estimate for the AIS is 54 ± 27 Gt/yr, which is in line with many recent GPS calibrated GIA estimates. Our GIA result displays the presence of significant uplift rates in the Amundsen Sea Embayment of West Antarctica, where strong uplift has been observed by GPS. Over the period February 2003 to October 2009, the entire AIS changed in mass by −84 ± 31 Gt/yr (West Antarctica: −69 ± 24, East Antarctica: 12 ± 16 and the Antarctic Peninsula: −27 ± 8), greater than the GRACE-only estimates obtained from three Mascon solutions (CSR: −50 ± 30, JPL: −71 ± 30, and GSFC: −51 ± 33 Gt/yr) for the same period. This may imply that single GRACE data tend to underestimate ice mass loss due to the signal leakage and attenuation errors of ice discharge are often worse than that of surface mass balance over the AIS.

scholarly journals Simultaneous solution for mass trends on the West Antarctic Ice Sheet

2014 ◽  
Vol 8 (3) ◽  
pp. 2995-3035 ◽  
Author(s):  
N. Schön ◽  
A. Zammit-Mangion ◽  
J. L. Bamber ◽  
J. Rougier ◽  
T. Flament ◽  
...  
Keyword(s):  
Mass Loss ◽  
Antarctic Peninsula ◽  
Ice Sheet ◽  
The West ◽  
Spatial Error ◽  
Antarctic Ice Sheet ◽  
Forward Models ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
The Antarctic

Abstract. The Antarctic Ice Sheet is the largest potential source of future sea-level rise. Mass loss has been increasing over the last two decades in the West Antarctic Ice Sheet (WAIS), but with significant discrepancies between estimates, especially for the Antarctic Peninsula. Most of these estimates utilise geophysical models to explicitly correct the observations for (unobserved) processes. Systematic errors in these models introduce biases in the results which are difficult to quantify. In this study, we provide a statistically rigorous, error-bounded trend estimate of ice mass loss over the WAIS from 2003–2009 which is almost entirely data-driven. Using altimetry, gravimetry, and GPS data in a hierarchical Bayesian framework, we derive spatial fields for ice mass change, surface mass balance, and glacial isostatic adjustment (GIA) without relying explicitly on forward models. The approach we use separates mass and height change contributions from different processes, reproducing spatial features found in, for example, regional climate and GIA forward models, and provides an independent estimate, which can be used to validate and test the models. In addition, full spatial error estimates are derived for each field. The mass loss estimates we obtain are smaller than some recent results, with a time-averaged mean rate of −76 ± 15 GT yr−1 for the WAIS and Antarctic Peninsula (AP), including the major Antarctic Islands. The GIA estimate compares very well with results obtained from recent forward models (IJ05-R2) and inversion methods (AGE-1). Due to its computational efficiency, the method is sufficiently scalable to include the whole of Antarctica, can be adapted for other ice sheets and can easily be adapted to assimilate data from other sources such as ice cores, accumulation radar data and other measurements that contain information about any of the processes that are solved for.

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