Accelerating ice loss from the fastest Greenland and Antarctic glaciers

Thomas, Robert H.; Frederick, E.; Li, J.; Krabill, William B.; Manizade, S.; Paden, John; Sonntag, J. G.; Swift, Robert N.; Yungel, James K.

doi:10.1029/2011gl047304

Cited by 40 publications

(34 citation statements)

References 21 publications

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“…Although additional grounding line retreat may result from creep thinning associated with altered ice stream dynamics [Thomas et al, 2011], our observations of accelerated thinning are consistent with measurements of changing oceanographic conditions at the glacier terminus over the period 1994-2009 [Jacobs et al, 2011]. These oceanographic data reveal strengthening circulation in an enlarged sub-ice shelf cavity, leading to faster ice melting.…”

Section: Discussionsupporting

confidence: 86%

Sustained retreat of the Pine Island Glacier

Park

Gourmelen

Shepherd

et al. 2013

Geophysical Research Letters

123

133

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[1] We use satellite observations to show that, between 1992 and 2011, the Pine Island Glacier hinge line retreated at a rate of 0.95 AE 0.09 km yr À1 despite a progressive steepening and shoaling of the glacier surface and bedrock slopes, respectively, which ought to impede retreat. The retreat has remained constant because the glacier terminus has thinned at an accelerating rate of 0.53 AE 0.15 m yr À2 , with comparable changes upstream. This acceleration is consistent with an intensification of ocean-driven melting in the cavity beneath the floating section of the glacier. The pattern of hinge-line retreat meanders and is concentrated in isolated regions until ice becomes locally buoyant. Because the glacier-ocean system does not appear to have reached a position of relative stability, the lower limit of sea level projections may be too conservative.

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Section: Discussionsupporting

confidence: 86%

Sustained retreat of the Pine Island Glacier

Park

Gourmelen

Shepherd

et al. 2013

Geophysical Research Letters

123

133

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“…Mass balance estimates based on flux-balance agree to within 15 % of most GRACE-based estimates for the period from 2003to 2008(van den Broeke et al, 2009. The balance has been consistently negative since 1999 owing to negative trends in surface mass balance (SMB) (Wake et al, 2009;Hanna et al, 2011) combined with increases in discharge .…”

Section: Introductionmentioning

confidence: 50%

“…Three major tidewater glaciers experienced large and rapid increases in flow speed: first, Jakobshavn Isbrae in the west, beginning in 1998 (Joughin et al, 2004;Luckman and Murray, 2005), followed by Helheim and Kangerdlugssuaq in 2002, respectively (Howat et al, 2005Luckman et al, 2006). The latter pair have since decelerated (Howat et al, 2007;Murray et al, 2010) but their earlier behaviour meant that, in the south-east, discharge dominated the total mass balance signal, whereas in the north-west the losses were equally distributed between surface processes and ice discharge (van den Broeke et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Glacier dynamics over the last quarter of a century at Helheim, Kangerdlugssuaq and 14 other major Greenland outlet glaciers

2012

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Abstract. The Greenland ice sheet is experiencing increasing rates of mass loss, the majority of which results from changes in discharge from tidewater glaciers. Both atmospheric and ocean drivers have been implicated in these dynamic changes, but understanding the nature of the response has been hampered by the lack of measurements of glacier flow rates predating the recent period of warming. Here, using Landsat-5 data from 1985 onwards, we extend back in time the record of surface velocities and ice-front position for 16 of Greenland's fastest-flowing tidewater glaciers, and compare these to more recent data from Landsat-7 and satellite-borne synthetic-aperture radar. Climate re-analysis data and sea surface temperatures from 1982 show that since 1995 most of Greenland and its surrounding oceans have experienced significant overall warming, and a switch to a warming trend. During the period from 1985 to 1995 when Greenland and the surrounding oceans were not warming, major tidewater outlet glaciers around Greenland, including Kangerdlugssuaq and Helheim, were dynamically stable. Since the mid-1990s, glacier discharge has consistently been both greater and more variable. Together, these observations support the hypothesis that recent dynamic change is a rapid response to climate forcing. Both air and ocean temperatures in this region are predicted to continue to warm, and will therefore likely drive further change in outlet glacier discharge.

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“…That widespread ice-sheet thinning arises from localized acceleration of ice streams is particularly significant when considering recent observations of velocity increases in both Antarctic and Greenland ice sheets (35).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

Golledge

Fogwill

Mackintosh

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

136

143

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Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments—a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.

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Accelerating ice loss from the fastest Greenland and Antarctic glaciers

Cited by 40 publications

References 21 publications

Sustained retreat of the Pine Island Glacier

Sustained retreat of the Pine Island Glacier

Glacier dynamics over the last quarter of a century at Helheim, Kangerdlugssuaq and 14 other major Greenland outlet glaciers

Dynamics of the last glacial maximum Antarctic ice-sheet and its response to ocean forcing

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