Abstract
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 Sjogren 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 Sjogren 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 Sjogren Inlet glaciers retreated 61.7±3.1 km² behind the former grounding line in 1996. For the glacier area below 1000 m a.s.l. and above the 2014 grounding (399 km²), 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 Sjogren Inlet glaciers (including the area above 1000 m a.s.l.) above the 2014 grounding line (559km2) 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
Highlights
On the northern Antarctic Peninsula substantial atmospheric changes have taken place in recent decades
Due to the continuous retreat of the Prince Gustav Ice Shelf, the Sjögren Inlet was no longer buttressed by the ice shelf in early 1993
The maximum retreat of −61.7 ± 3.1 km2 is mapped on the TanDEM-X Synthetic Aperture Radar (SAR) image from April 6, 2014, which correlates to the loss of grounded ice
Summary
On the northern Antarctic Peninsula substantial atmospheric changes have taken place in recent decades. Scambos et al (2003) linked the instability and recession of ice shelves to an increase in summer air temperatures and surface melt. Significant glacier surface lowering was observed by Berthier et al (2012) and Scambos et al (2004) as a consequence of increased ice discharge. Based on photogrammetric digital elevation models (DEMs), a mass change rate of −24.9 ± 7.8 Gt a−1 (2003–2008) for the northern Antarctic Peninsula was found by Scambos et al (2014). Ivins et al (2011) reported a current ice mass change rate of −41.5 ± 9 Gt a−1 from analysis of GRACE time series and bedrock uplift data. Shepherd et al (2012) performed an integrated glacier mass balance compilation of the Antarctic and Greenland ice sheets based on modeling results and observation data. The regional estimates show a significant mass loss at the Antarctic Peninsula, the individual imbalance results vary strongly and have uncertainties of up to 70%
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