scholarly journals The Impact of the Amundsen Sea Freshwater Balance on Ocean Melting of the West Antarctic Ice Sheet

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
David T. Bett ◽  
Paul R. Holland ◽  
Alberto C. Naveira Garabato ◽  
Adrian Jenkins ◽  
Pierre Dutrieux ◽  
...  
Keyword(s):  
Ice Sheet ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
The Impact ◽  
Freshwater Balance

Active subglacial volcanism in West Antarctica as assessed by airborne geophysics: Distribution and context

2020 ◽  
Author(s):  
Donald Blankenship ◽  
Enrica Quatini ◽  
Duncan Young
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Rift System ◽  
West Antarctica ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Volcanism

<p>A combination of aerogeophysics, seismic observations and direct observation from ice cores and subglacial sampling has revealed at least 21 sites under the West Antarctic Ice sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogenous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially underrepresented. Unsurprisingly, the sites of active subglacial volcanism we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea to Siple Coast lithospheric transition.</p>

Chapter 7.5 Active subglacial volcanism in West Antarctica

2021 ◽  
pp. M55-2019-3
Author(s):  
Enrica Quartini ◽  
Donald D. Blankenship ◽  
Duncan A. Young
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Rift System ◽  
West Antarctica ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Volcanism

AbstractA combination of aerogeophysics, seismic observations and direct observation from ice cores, and subglacial sampling, has revealed at least 21 sites under the West Antarctic Ice Sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogeneous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially under-represented. Unsurprisingly, the sites of active subglacial volcanism that we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal-thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea–Siple Coast lithospheric transition.

Sedimentary signature of past West Antarctic Ice Sheet and ocean dynamics from deep sea drill cores in the Amundsen Sea (IODP Expedition 379)

2021 ◽  
Author(s):  
Delaney E. Robinson ◽  
Julia S. Wellner ◽  
Karsten Gohl ◽  
Benedict T.I. Reinardy ◽  
Keyword(s):  
Grain Size ◽  
Ice Sheet ◽  
Silty Clay ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Depositional Processes ◽  
Drill Cores

<p>Modern observations of the West Antarctic Ice Sheet (WAIS) show relatively warm ocean water causing negative changes in ice-sheet mass. The largest ice mass loss in the WAIS occurs in the Amundsen Sea region, where warm water flows onto the shelf and melts the marine-based ice shelves, a process with the potential to lead to full collapse of the WAIS. Geologic records from similar and warmer climate conditions than today are required to understand the role of changes affecting the Amundsen Sea drainage sector in steering past WAIS dynamics. International Ocean Discovery Program (IODP) Expedition 379 successfully recovered sediment drill cores from two sites on the continental rise in the Amundsen Sea, West Antarctica. Both sites are located on a large sediment drift that provides a continuous, long-term record of glacial history in a drainage basin that is fed exclusively by the WAIS. Sediments at both sites are associated with depositional processes related to glacial extent on the shelf. Repeated alternations of two major facies groups composed of dark-gray laminated silty clay and massive/bioturbated greenish-gray, clast-bearing mud are interpreted to represent cycles of glacial and interglacial periods. High-resolution sedimentological analyses define characteristics that vary within the two broad sedimentary facies, helping provide constraints on depositional processes of the sediments and controlling WAIS dynamics.</p><p>Detailed investigations were conducted on Miocene to Pliocene strata using grain size and shape analysis, combined with X-Ray Fluorescence data and computer tomography scans, as well as detailed thin section analysis. Laminated silty clay intervals contain consistently fine-grained sediments dominated by terrigenous components that were supplied by downslope transport during glacial periods. Massive/bioturbated muds with ice rafted debris (IRD) display variable grain size trends accompanied by changes in particular elemental ratios indicating increased supply of biogenic components and possibly reduced delivery of terrigenous detritus during interglacial periods. The boundaries between massive, interglacial facies and laminated, glacial facies are usually sharp; although occasionally, a more gradual interglacial-glacial transition is observed. Different sedimentation patterns suggest fluctuations in downslope transport and bottom current intensities that are connected to ice sheet extent on the West Antarctic continental shelf. Further analysis may reveal facies characteristics that vary with glacial-interglacial cycles and allow improved interpretation of past WAIS dynamics and Southern Ocean circulation.</p>

scholarly journals Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

2015 ◽  
Vol 9 (4) ◽  
pp. 1579-1600 ◽  
Author(s):  
S. L. Cornford ◽  
D. F. Martin ◽  
A. J. Payne ◽  
E. G. Ng ◽  
A. M. Le Brocq ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Ice Shelf ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Accumulation ◽  
Grounding Line ◽  
Ocean Models

Abstract. We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.

scholarly journals Retreat of the West Antarctic Ice Sheet from the western Amundsen Sea shelf at a pre- or early LGM stage

2014 ◽  
Vol 91 ◽  
pp. 1-15 ◽  
Author(s):  
J.P. Klages ◽  
G. Kuhn ◽  
C.-D. Hillenbrand ◽  
A.G.C. Graham ◽  
J.A. Smith ◽  
...  
Keyword(s):  
Ice Sheet ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

scholarly journals Global estimates of the impact of a collapse of the West Antarctic ice sheet: an application of FUND

2008 ◽  
Vol 91 (1-2) ◽  
pp. 171-191 ◽  
Author(s):  
Robert J. Nicholls ◽  
Richard S. J. Tol ◽  
Athanasios T. Vafeidis
Keyword(s):  
Ice Sheet ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Global Estimates ◽  
The Impact

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>

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