Title Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf Permalink (original) (raw)
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Northern Larsen Ice Shelf, Antarctica: further retreat after collapse
Annals of Glaciology, 2002
Changes of Larsen Ice Shelf, Antarctica, and the surrounding glaciers after its collapse in 1995 were investigated using satellite radar imagery, with emphasis on changes in the glaciers which previously nourished the ice shelf north of Seal Nunataks and now calve directly into the sea. The large glaciers retreated several kilometres inland of the previous grounding line. The velocity field of Drygalski Glacier, the largest glacier in this area, was mapped by means of interferograms derived from pairs of European Remote-sensing Satellite synthetic aperture radar images from 1995 and 1999. The main part of the glacier showed a significant acceleration of flow over these 4 years, with an increase of velocity up to three-fold at the terminus. Similar accelerations were observed by means of interferometry on several other grounded glaciers, suggesting that the removal of ice shelves could lead to an effect on eustatic sea level. For Larsen B, the northernmost surviving part of Larsen Ic...
International Journal of Geosciences, 2013
As to sea level rise (SLR) contribution, melting and setting afloat make no difference for land based ice. Melting of West Antarctic Ice Sheet (WAIS) into water is impossible in the upcoming several centuries, whereas breaking and partially afloat is likely as long as sea waters find a pathway to the bottom of those ice sectors with basal elevation below sea level. In this sense WAIS may be disintegrated in a future warming climate. We reassess the potential contribution to eustatic sea level from a collapse of WAIS and find that previous assessments have overlooked a contributor: slope instability after the cementing ice is removed. Over loading ice has a buttressing effect on slope movements the same way ice shelves hinder the flow of non-floating coastal ice. A sophisticated landslide model estimates a 9-mm eustatic SLR contribution from subsequent landslides.
Evolution of surface velocities and ice discharge of Larsen B outlet glaciers from 1995 to 2013
The Cryosphere, 2015
We use repeat-pass SAR data to produce detailed maps of surface motion covering the glaciers draining into the former Larsen B ice shelf, Antarctic Peninsula, for different epochs between 1995 and 2013. We combine the velocity maps with estimates of ice thickness to analyze fluctuations of ice discharge. The collapse of the central 5 and northern sections of the ice shelf in 2002 led to a near-immediate acceleration of tributary glaciers as well as of the remnant ice shelf in Scar Inlet. Velocities of the glaciers discharging directly into the ocean remain to date well above the velocities of the pre-collapse period. The response of individual glaciers differs and velocities show significant temporal fluctuations, implying major variations in ice discharge and mass 10 balance as well. Due to reduced velocity and ice thickness the ice discharge of Crane Glacier decreased from 5.02 Gt a −1 in 2007 to 1.72 Gt a −1 in 2013, whereas Hektoria and Green glaciers continue to show large temporal fluctuations in response to successive stages of frontal retreat. The velocity on Scar Inlet ice shelf increased two-to three fold since 1995, with the largest increase in the first years after the break-up of 15 the main section of Larsen B. Flask and Leppard glaciers, the largest tributaries to Scar Inlet ice shelf, accelerated. In 2013 their discharge was 38 %, respectively 45 %, higher than in 1995.
Frontiers in Earth Science, 2016
The substantial retreat or disintegration of numerous ice shelves has been observed on the Antarctic Peninsula. The ice shelf in the Prince Gustav Channel has retreated gradually since the late 1980s and broke up in 1995. Tributary glaciers reacted with speed-up, surface lowering and increased ice discharge, consequently contributing to sea level rise. We present a detailed long-term study (1993-2014) of the dynamic response of Sjögren Inlet glaciers to the disintegration of the Prince Gustav Ice Shelf. We analyzed various remote sensing datasets to identify the reactions of the glaciers to the loss of the buttressing ice shelf. A strong increase in ice surface velocities was observed, with maximum flow speeds reaching 2.82 ± 0.48 m d −1 in 2007 and 1.50 ± 0.32 m d −1 in 2004 at Sjögren and Boydell glaciers respectively. Subsequently, the flow velocities decelerated, however in late 2014, we still measured approximately twice the values of our first observations in 1996. The Sjögren Inlet glaciers retreated 61.7 ± 3.1 km 2 behind the former grounding line in 1996. For the glacier area below 1000 m a.s.l. and above the 2014 grounding (399 km 2), a mean surface lowering of −68 ± 10 m (−3.1 m a −1) was observed in the period 1993-2014. The lowering rate decreased to −2.2 m a −1 in the period 2012-2014. Based on the surface lowering rates, geodetic mass balances of the glaciers were derived for different time periods. A strongly negative mass change rate of −1.16 ± 0.38 Gt a −1 was found for the area of all Sjögren Inlet glaciers (including the area above 1000 m a.s.l.) above the 2014 grounding line (559 km 2) for the earliest period (1993-2001). Due to the dynamic adjustments of the glaciers to the new boundary conditions the rate changed to −0.54 ± 0.13 Gt a −1 in the period 2012-2014, resulting in an average mass change rate of −0.84 − ± 0.18 Gt a 1 (1993-2014) for the same domain. Including the retreat of the ice front and grounding line, a total mass change of −37.5 ± 8.2 Gt (−1.79 ± 0.39 Gt a −1) and a contribution to sea level rise of 20.9 ± 5.2 Gt (−0.99 ± 0.25 Gt a −1) were computed for the period 1993-2014. Analysis of the ice flux revealed that available bedrock elevation estimates at Sjögren Inlet are too shallow Seehaus et al. Glacier Dynamics at Sjögren Inlet and are the major uncertainty in ice flux computations. This temporally dense time series analysis of Sjögren Inlet glaciers shows that the adjustments of tributary glaciers to ice shelf disintegration are still ongoing and provides detailed information of the changes in glacier dynamics.
Volume loss from Antarctic ice shelves is accelerating
Science (New York, N.Y.), 2015
The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using eighteen years of continuous satellite radar altimeter observations we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km(3) per year for 1994-2003 to rapid loss of 310 ± 74 km(3) per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.