Century‐scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica

Hulbe, Christina L.; Fahnestock, M. A.

doi:10.1029/2006jf000603

Cited by 104 publications

(86 citation statements)

References 62 publications

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“…A detailed summary of the current knowledge is provided in Catania et al (2012). The aspects most relevant for this study are a shutdown of Whillans Ice Stream about 850 yr ago (Catania et al, 2010) and the subsequent restart about 450 yr ago (Hulbe and Fahnestock, 2007). Our results and earlier studies in the region (Joughin et al, 2002(Joughin et al, , 2005 show that dynamic changes in the region are ongoing.…”

Section: Discussionsupporting

confidence: 63%

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

2012

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Abstract. We report changes in ice velocity of a 6.5 million km 2 region around South Pole encompassing the Filchner-Ronne and Ross Ice Shelves and a significant portion of the ice streams and glaciers that constitute their catchment areas. Using the first full interferometric synthetic aperture radar (InSAR) coverage of the region completed in 2009 and partial coverage acquired in 1997, we processed the data to assemble a comprehensive map of ice speed changes between those two years. On the Ross Ice Shelf, our results confirm a continued deceleration of Mercer and Whillans Ice Streams with a 12-yr velocity difference of −50 m yr −1 (−16.7 %) and −100 m yr −1 (−25.3 %) at their grounding lines. The deceleration spreads 450 km upstream of the grounding line and more than 500 km onto the shelf, beyond what was previously known. Ross and Filchner Ice Shelves exhibit signs of pre-calving events, representing the largest observed changes, with an increase in speed in excess of +100 m yr −1 in 12 yr. Other changes in the Ross Ice Shelf region are less significant. The observed changes in glacier speed extend on the Ross Ice Shelf along the ice streams' flow lines. Most tributaries of the Filchner-Ronne Ice Shelf show a modest deceleration or no change between 1997 and 2009. Slessor Glacier shows a small deceleration over a large sector. No change is detected on the Bailey, Rutford, and Institute Ice Streams. On the Filchner Ice Shelf itself, ice decelerated rather uniformly with a 12-yr difference in speed of −50 m yr −1 , or −5 % of its ice front speed, which we attribute to a 12 km advance in its ice front position. Our results show that dynamic changes are present in the region. They highlight the need for continued observation of the area with a primary focus on the Siple Coast. The dynamic changes in Central Antarctica between 1997 and 2009 are generally second-order effects in comparison to losses on glaciers in the Bellingshausen and Amundsen Seas region and on the Antarctic Peninsula. We therefore conclude that the dynamic changes shown here do not have a strong impact on the mass budget of the Antarctic continent.

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Section: Discussionsupporting

confidence: 63%

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

2012

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“…The biggest single velocity error in Fig. 9 is due to the Kamb Ice Stream (Ice Stream C) on the Siple Coast, which stagnated about 150 yr ago (Hulbe and Fahnestock, 2007), but in the model is flowing at velocities comparable to the other active Ross ice streams. This type of fluctuation could be stochastic in nature (Payne, 1999;PD09 Supp.…”

Section: Modern Resultsmentioning

confidence: 99%

Description of a hybrid ice sheet-shelf model, and application to Antarctica

2012

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Abstract. The formulation of a 3-D ice sheet-shelf model is described. The model is designed for long-term continentalscale applications, and has been used mostly in paleoclimatic studies. It uses a hybrid combination of the scaled shallow ice and shallow shelf approximations for ice flow. Floating ice shelves and grounding-line migration are included, with parameterized ice fluxes at grounding lines that allows relatively coarse resolutions to be used. All significant components and parameterizations of the model are described in some detail. Basic results for modern Antarctica are compared with observations, and simulations over the last 5 million years are compared with previously published results. The sensitivity of ice volumes during the last deglaciation to basal sliding coefficients is discussed.

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“…As the ICESat observations of ice-sheet dynamics only covered a single 6 year period from 2003 to 2009, only one instance of water flow switching has been captured by this dataset, though a second activation of SLW in 2013 [30] probably indicates another instance of water piracy. There is evidence for multiple episodes of switching on and off between both WIS and KIS over the past 1000 years [40]. Thus, it is likely that hydrological systems supplying water to both SLW and the grounding zone downstream have switched on and off multiple times, much like a subaerial braided stream channel, and periodically deliver water, solutes and particulates mixed from across the catchment into the ocean.…”

Section: Ecological Setting Of Subglacial Lake Whillansmentioning

confidence: 99%

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

Mikucki

Lee

Ghosh

et al. 2016

Phil. Trans. R. Soc. A.

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Liquid water occurs below glaciers and ice sheets globally, enabling the existence of an array of aquatic microbial ecosystems. In Antarctica, large subglacial lakes are present beneath hundreds to thousands of metres of ice, and scientific interest in exploring these environments has escalated over the past decade. After years of planning, the first team of scientists and engineers cleanly accessed and retrieved pristine samples from a West Antarctic subglacial lake ecosystem in January 2013. This paper reviews the findings to date on Subglacial Lake Whillans and presents new supporting data on the carbon and energy metabolism of resident microbes. The analysis of water and sediments from the lake revealed a diverse microbial community composed of bacteria and archaea that are close relatives of species known to use reduced N, S or Fe and CH4 as energy sources. The water chemistry of Subglacial Lake Whillans was dominated by weathering products from silicate minerals with a minor influence from seawater. Contributions to water chemistry from microbial sulfide oxidation and carbonation reactions were supported by genomic data. Collectively, these results provide unequivocal evidence that subglacial environments in this region of West Antarctica host active microbial ecosystems that participate in subglacial biogeochemical cyclingauthorsversionPeer reviewe

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Century‐scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica

Cited by 104 publications

References 62 publications

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

Ice velocity changes in the Ross and Ronne sectors observed using satellite radar data from 1997 and 2009

Description of a hybrid ice sheet-shelf model, and application to Antarctica

Subglacial Lake Whillans microbial biogeochemistry: a synthesis of current knowledge

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