Repeat Subglacial Lake Drainage and Filling Beneath Thwaites Glacier, West-Antarctic Ice Sheet

2020 ◽  
Author(s):  
George Malczyk ◽  
Daniel Goldberg ◽  
Noel Gourmelen ◽  
Jan Wuite ◽  
Thomas Nagler
Keyword(s):  
Ice Sheet ◽  
Catchment Scale ◽  
Amundsen Sea ◽  
Ice Dynamics ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Subglacial Lake ◽  
West Antarctic ◽  
Lake Drainage ◽  
Subglacial Lakes

<p>Active subglacial lakes have been identified throughout Antarctica, offering a window into subglacial environments and into controls on ice dynamics. Between June 2013 and January 2014 a system of connected subglacial lakes drained in unison under the Thwaites glacier in the West Antarctic ice sheet, the first time that such a system has been observed in the Amundsen Sea Sector. Estimates based on catchment scale melt production suggested that lake drainages of this type should occur every 20 to 80 years. We collected elevations from January 2011 to December 2019 over the Thwaites lake region using the CryoSat-2 swath interferometric mode and ICEsat-2 land ice elevations, as well as ice velocity from the Sentinel-1 SAR mission since 2014. Using various elevation time series approaches, we obtain time dependent elevations over each lake. Results indicate that the upstream lakes undertake a second episode of drainage during mid-2017, only 3 years after the previous event, and that a new lake drained. Unlike the 2013-2014 episode, this new drainage episode contributed to filling one of the downstream lake with no evidence of further downstream activity. This new sub-glacial lake activity under Thwaites offer the possibility to explore lake connectivity, subglacial melt production and the interaction with ice dynamics.</p>

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>

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

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.

No evidence for a Pleistocene collapse of the West Antarctic Ice Sheet from continental margin sediments recovered in the Amundsen Sea

2002 ◽  
Vol 22 (2) ◽  
pp. 51-59 ◽  
Author(s):  
Claus-Dieter Hillenbrand ◽  
Dieter Fütterer ◽  
Hannes Grobe ◽  
Thomas Frederichs
Keyword(s):  
Continental Margin ◽  
Ice Sheet ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

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

Evolution of the Antarctic ice sheet: new understanding and challenges

2006 ◽  
Vol 364 (1844) ◽  
pp. 1867-1872 ◽  
Author(s):  
Antony J Payne ◽  
Julian C.R Hunt ◽  
Duncan J Wingham
Keyword(s):  
Ice Sheet ◽  
Ice Streams ◽  
International Polar Year ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Future Challenges ◽  
International Polar ◽  
The Antarctic

This brief paper has two purposes. First, we gauge developments in the study of the Antarctic ice sheet over the last seven years by comparing the contents of this issue with the volume produced from an American Geophysical Union meeting, held in September 1998, on the West Antarctic ice sheet. We focus on the uptake of satellite-based observation; ice–ocean interactions; ice streams as foci of change within the ice sheet; and the time scales on which the ice sheet is thought to operate. Second, we attempt to anticipate the future challenges that the study of the Antarctic ice sheet will present. We highlight the role of the upcoming International Polar Year in facilitating a better coverage of in situ climatic observations over the continent; the pressing need to understand the causes and consequences of the contemporary changes observed in the Amundsen Sea sector of West Antarctica; and the need for improved physics in predictive models of the ice sheet.

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