Recession and Ice Surface Elevation Changes of Baranowski Glacier and Its Impact on Proglacial Relief (King George Island, West Antarctica)
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geosciences Article Recession and Ice Surface Elevation Changes of Baranowski Glacier and Its Impact on Proglacial Relief (King George Island, West Antarctica) Joanna Sziło 1,* and Robert Józef Bialik 2 1 Institute of Geophysics, Polish Academy of Sciences, ul. Ksi˛eciaJanusza 64, 01-452 Warsaw, Poland 2 Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawi´nskiego 5a, 02-106 Warsaw, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-504-595-266 Received: 27 July 2018; Accepted: 18 September 2018; Published: 20 September 2018 Abstract: Glacial forefields areas are dynamic landscapes, and due to the glacier frontal position changes, they are sensitive to climatic fluctuations. The results of the analysis of aerial photos, satellite imagery, archival maps, and terrestrial laser scanning surveys are presented. These investigations reveal that the ice surface decreased during the period 1989–2001, when almost the entire current forefield was already uncovered. Moreover, it is shown that, since 1969, there has been a relationship between the changes in air temperature and the changes of the annual front position rate of Baranowski Glacier. Specifically, the results demonstrate that during the cooling observed for the Antarctic Peninsula Regions since 2000, there is a deceleration of the recession rate and ice surface elevation changes of Baranowski Glacier. It is also shown that the fluctuation of the areal extent of the glacier as well as ice surface elevation changes are closely associated with proglacial relief. Moreover, it is shown that the difference in the retreat of the northern and southern tongue of the glacier can be explained by the presence of relatively warm water in the shallow bay, which can enhance the melting process of the northern part. In addition, existence of long flutes and crevasse fill ridges on the analyzed forefield of Baranowski Glacier suggest that the former episodes of its surge, which could happen at least in the northern part of the forefield and middle part of the southern forefield of the glacier. Keywords: deglaciation; proglacial landform; ice surface elevation changes; terrestrial laser scanning 1. Introduction Melting glaciers and changes in the frozen ground conditions, primarily controlled by climate changes, strongly influence the geomorphological processes occurring in ice-free areas [1] defined here as glacial forefields. Moreover, glaciers in polar regions play important roles in the functions of local [2] and global ecosystems [3]. Thus, studies on the reaction of glaciers to climate fluctuations [4–6] and their impacts on the regional environment are exceptionally important [7]. Since the 1950’s, regional warming has been observed on the Antarctic Peninsula [8–12] with an increased in air temperature of 0.32 ◦C/decade from 1979 to 1997 [13]. Nevertheless, several authors [13,14] have reported a cooling trend over the last 20 years, with a decreased air temperature of −0.47 ◦C/decade over the period 1999–2014 [13]. These findings, however, depend on data interpretation. For Bellingshausen Station on King George Island (KGI), the air temperature reached a maximum in 1989 and the relatively stable fluctuations of air temperature were observed until 2009 (Figure1;[ 15]). Based on these data, the cooling noted above could be suggested for only the summer months during the period 2012–2015, as shown by P˛etlicki et al. [16]. Oliva et al. [13] suggested that the Geosciences 2018, 8, 355; doi:10.3390/geosciences8100355 www.mdpi.com/journal/geosciences Geosciences 2018, 8, x 355 FOR PEER REVIEW 22 of 1817 the recent cooling was amplified by an increasing extent of sea ice, which, in 2014 [17], reached its highestrecent cooling value since was amplified 1979. However, by an increasing the difference extent of of mean sea ice, annual which, temperature in 2014 [17], between reached its2015 highest and 2016value sincewas 1979.1.2 However,°C (Figure the difference1, [15]), of meanwhereas annual the temperature mean betweenannual 2015air andtemperature 2016 was for1.2 ◦FieldesC (Figure Peninsula1,[ 15]), was whereas −2.3 °C the for mean the period annual 1969–2017. air temperature Simultaneously, for Fieldes the Peninsula Antarctic was ice− extent2.3 ◦C wasfor theminimal period 1969–2017.in 2016–2017 Simultaneously, [17]. In addition, the Antarctic during iceyears extent of wassuggeste minimald cooling, in 2016–2017 decreased [17]. precipitationIn addition, during has been years reported of suggested (Figure cooling, 1). decreased precipitation has been reported (Figure1). Figure 1. MeanMean annual annual air air temperature temperature and and sum sum of of the the pr precipitationecipitation at at Bellingshausen Bellingshausen Station Station (Fieldes (Fieldes Peninsula) in the period 1969–2017 [15]. [15]. The reactions of glaciers, generally generally in in the the form form of of mass mass loss loss [18], [18], glacier glacier recession recession [13], [13], and decreased decreased ice ice surface surface elevation elevation [16], [16 have], have been been observed, observed, especially especially for those for thoselocated located in the inSouth the ShetlandSouth Shetland Islands Islands [18–23]. [18 –Since23]. Since1956, 1956, climate climate warming warming has hasbeen been the the main main factor factor causing causing these changes. Special Special attention attention has has been been paid paid to to the gl glaciersaciers located within Admiralty Bay [16,19,24–31] [16,19,24–31] and others that drain drain the the Warszawa Warszawa Ice field field [20,32,33]. [20,32,33]. The The effects effects of of climate climate change change were were confirmed, confirmed, for example,example, on on the the Ecology Ecology and Sphinxand Sphinx glaciers glac betweeniers between 2012 and 20132012 inand the form2013 ofin a short-termthe form ofnegative a short-term mass balancenegative [ 24mass]. Importantly, balance [24]. most Importan of thetly, glaciers most of covering the glaciers KGI covering terminate KGI in terminate tidewater insettings tidewater with recessionsettings with not yet recession leading tonot the yet development leading to of the subaerially development exposed of forefields,subaerially whereas exposed for forefields,land-based whereas glaciers, for front land-based position changes glaciers, are front substantial position and changes are directly are substantial associated and with are periglacial directly associatedprocesses, permafrostwith periglacial degradation processes, and permafrost the spread ofdegradation vegetation and on the the newly spread ice-free of vegetation areas [1 ,34on– 37the]. newlyWhile ice-free many areas studies [1,34–37]. have been carried out on KGI, not enough attention has been devoted to the BaranowskiWhile many Glacier, studies the have central been glacier carried located out on on KGI, the Western not enough shore attention of Admiralty has been Bay. Sincedevoted the toearly the 1980s,Baranowski this glacier Glacier, has the terminated central glacier on land. loca Theted basin on the is aWestern unique shore region of with Admiralty a large proportionBay. Since theof ice-freeearly 1980s, area onthis which glacier climatic has terminated fluctuations on andland. glacial The basin evolution is a impactunique theregion recent with proglacial a large proportionlandscape [38of ,39ice-free]. Geomorphological area on which climatic observations fluctuations were conducted and glacial in evolution this area betweenimpact the 1984 recent and proglacial1986 [40] and landscape from 1990 [38,39]. to 1992 Geom duringorphological the Polish observations expeditions were to KGI conducted [38,41,42 in]. Sincethis area then, between due to 1984the recession and 1986 of [40] the and glacier, from the 1990 forefield to 1992 has during changed the Polish considerably. expeditions Therefore, to KGI the[38,41,42]. main goals Since of then, this dueresearch to the are recession (1) to present of the glacier, the relationships the forefield between has changed the recession considerably. of Baranowski Therefore, Glacier the main and goals the ofavailable this research climate are data (1) to from present KGI sincethe relationsh 1956; (2)ips to supplementbetween the ourrecession knowledge of Baranowski about the Glacier ice surface and theelevation available changes climate of data the from glaciers KGI located since 1956; on KGI, (2) to based supplement on the our observation knowledge of about Baranowski the ice surface Glacier elevationsince 1989; changes and (3) of to improvethe glaciers our located understanding on KGI, ofbased the relief on the of thisobservation proglacial of regionBaranowski in front Glacier of the sinceBaranowski 1989; Glacier.and (3) to improve our understanding of the relief of this proglacial region in front of the Baranowski Glacier. 2. Materials and Methods 2.2.1. Materials Study Site and Methods 2.1. StudyThe Baranowski Site Glacier is located on the Western shore of Admiralty Bay on KGI (West Antarctica), the largest island of the South Shetland Islands archipelago (Figure2a). The island is separated from The Baranowski Glacier is located on the Western shore of Admiralty Bay on KGI (West the Antarctic Peninsula by the Bransfield Strait by a distance of approximately 120–130 km. The total Antarctica), the largest island of the South Shetland Islands archipelago (Figure 2a). The island area of the island is 1250 km2, and almost the entire island is covered by ice caps (Figure2b). The glacier is separated