Abstract
Antarctica is a region of the world where climate change is visible in the rapid melting of glaciers. This is particularly evident in marginal zones, where the pace of glacial retreat has systematically accelerated. The effective mapping of these changes is possible with the use of remote sensing methods. This study assesses changes in glacier margin positions between 1979 and 2018 in the Antarctic Specially Protected Area 128 (ASPA-128) on King George Island, South Shetland Islands, Antarctica. In 1979, 19.8 km2 of the study area was glaciated. Over the following 39 years, an area of 6.1 km2 became ice-free, impacting local ecosystems both on land and in Admiralty Bay. The reduction in glacier extent was different in time and depended on the glacier type. Land-terminating glaciers had the fastest retreat rates below 200 m a.s.l. and were influenced mostly by surface melting. The reduction of tidewater glaciers occurred primarily in areas below 100 m a.s.l., with the most pronounced ice extent decreases occurring below 50 m a.s.l. The observed rates of front retreat suggest that glacier retreat rates were fastest between 1989–2001 and 2007–2011, with reduced retreat rates between 2001 and 2007. During the last 7 years, the lowest rate of regression was recorded in the entire analysed period (1979–2018). Changes in the areal extent of glaciers were compared with the climate record available for King George Island. The observed fluctuations in glacier retreat rates could be correlated to oscillations in annual Positive Degree-Days. The spatial analyses were based on aerial photographs (1956, 1979), theodolite measurements (1989), GPS survey (2001, 2007), and satellite images (2011, 2018).
Highlights
The Antarctic Peninsula region and islands of the southern Atlantic Ocean have been identified as a region of notable dynamic change in glacial and climatic systems [1,2,3,4,5]
The goal of this study is to examine the temporal variability and scale of glacier retreat in the eastern part of the Warszawa Icefield in the Antarctic Special Protected Area No 128 (ASPA-128, Figure 1) on King George Island on the background of the observed changes in weather elements
The surface temperature warming observed in the Antarctic Peninsula region in the last few decades [2,3] resulted in a reduced seasonal snow cover [40], an increased ablation of glacier ice located below the glacier’s Equilibrium-Line Altitude (ELA) [30], an increased snowfall which could increase the future ice discharge from feeding areas [41], and it may have caused an increased rate of sublimation and evaporation, further contributing to the removal of ~9% of precipitation in the Antarctic Peninsula region [42]
Summary
The Antarctic Peninsula region and islands of the southern Atlantic Ocean have been identified as a region of notable dynamic change in glacial and climatic systems [1,2,3,4,5]. Over the last 50 years, large areas along the southern shoreline of King George Island have become ice-free. Several new nunataks have emerged, illustrating a significant reduction of glacier thickness. The late-Holocene maximum extent of glaciers on King George Island is marked by large ice-cored moraines, which. 2018, 10, x FOR PEER REVIEW were formed at the termination of the Little Ice Age (LIA) at the beginning of the 20th century [6]. Remote Sens. 2018, 10, x FOR PEER REVIEW were formed at the termination of the Little Ice Age (LIA) at the beginning of the 20th century [6].
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