Contrasting responses of land-terminating glaciers to recent climate variations in King George Island, Antarctica

Abstract

In this study, we aim to analyse the glacier dynamics of land-terminating glaciers in King George Island (Antarctica) between 1956 and 2018. Glacial fluctuations are estimated using space-borne remote sensing data (SPOT, Landsat, PlanetScope, Sentinel-1, Sentinel-2, WorldView-2 and TanDEM-X). The eastern sector of Warszawa Icefield witnessed continuous glacier retreat during 1979–2018 (surface loss of 30%). The decreases in the ice-covered areas of the Tower, Windy, Ecology, Baranowski and Sphinx glaciers were 70%, 31%, 25%, 25% and 21%, respectively, with their accumulation area ratios (AARs) exhibiting negative mass balances. The winter air temperature was cooler during the 1970s with warming trends in the 1980s and early 2000s followed by a cooling trend until the present day. However, the annual time series has shown high interannual variability in air temperature during these periods. We show that the AAR, dimensions, length, frontal elevation, maximum elevation, slope and changes in the terminus position influence the glacier response to climate change at various timescales. Furthermore, three geomorphic activity intensity zones and a complete paraglacial sequence are identified while contrasting the proglacial systems. Overall, subglacial deposits predominate and indicate that meltwater flows on the bed, producing wet-based thermal regimes.

Terrestrial Signature of a Recently-Tidewater Glacier and Adjacent Periglaciation, Windy Glacier (South Shetland Islands, Antarctic)

“…Results of our large-scale geomorphological mapping of Windy Glacier foreland disagrees with the small-scale mapping of the same area performed by Da Rosa et al (2020) based solely on satellite images. For example, stretches of beach are interpreted in the mentioned study as recessional moraine ridges, and a very well visible recessional moraine complex on Patelnia Point (Supplementary Figure 1 and Figure 3) is not mapped by Da Rosa et al (2020). Furthermore, the referenced study depicts three zones in terms of proglacial geomorphic activity: (i) zone of high activity (deglaciated in years 2000 -2018, characterized by intensive paraglacial susceptibility), (ii) zone of moderate activity, deglaciated in years 1970s -2000, and (iii) zone of low activity, deglaciated before 1970.…”

“…This is because contemporary intensive rilling and gullying can be seen on a slope in the western part of the foreland, immediately below the latero-frontal moraine ridge, deglaciated since 1979 (Figures 2, 3). However, this area was labeled by Da Rosa et al (2020) as the low activity zone, deglaciated before 1970s.…”

“…New ice-free oasis are developed due to recent on-shore termination of formerly tidewater glaciers. The southern and eastern margins of the Warszawa Icefield (Figure 1) on King George Island (KGI), South Shetland Islands, are also subjected to retreat which transformed tidewater glacial fronts to land-terminating ones and liberated from glacial ice over 6 km 2 since the first general survey in 1979 (Pudełko, 2003;Pętlicki et al, 2017;Pudełko et al, 2018;Da Rosa et al, 2020).…”

“…The development of the terrestrial glacial landforms in front of the retreating glacier and periglacial phenomena in this area received considerable attention since the end of the 20th century due to the nearby location of the Henryk Arctowski Polish Antarctic Station (Arctowski) (Birkenmajer, 1980;Dutkiewicz, 1982;Kostrzewski et al, 1998Kostrzewski et al, , 2002Rachlewicz, 1999). Satellite and conventional aerial imagery recently allowed for deepening our understanding of glacial dynamics and gave some information on the rate of development of glacial landforms (Pętlicki et al, 2017;Pudełko et al, 2018;Sziło and Bialik, 2018;Da Rosa et al, 2020), however, they sometimes lead to improper interpretations.…”

“…The analysis of the landform assemblages allowed to infer about the glacial dynamics and the significance of contemporary periglacial processes developed in the adjacent area. Moreover, we critically address the previous geomorphological mapping of the area under study based on satellite images (Da Rosa et al, 2020).…”