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  • Author: Małgorzata Błaszczyk x
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Open access

Małgorzata Błaszczyk, Jacek A. Jania and Leszek Kolondra

Abstract

Significant retreat of glaciers terminating in Hornsund Fjord (Southern Spits− bergen, Svalbard) has been observed during the 20th century and in the first decade of the 21st century. The objective of this paper is to present, as complete as possible, a record of front positions changes of 14 tidewater glaciers during this period and to distinguish the main factors influencing their fluctuations. Results are based on a GIS analysis of archival maps, field measurements, and aerial and satellite images. Accuracy was based on an as− sessment of seasonal fluctuations of a glacier’s ice cliff position with respect to its mini− mum length in winter (November-December) and its maximum advance position in June or July.Morphometric features and the environmental setting of each glacier are also pre− sented. The total area of the glacier cover in Hornsund Fjord in the period of 1899-2010 diminished approximately 172 km2, with an average areal retreat rate of 1.6 km2a−1. The recession rate increased from ~1 km2a−1 in first decades of the 20th century up to ~3 km2a−1 in years 2001-2010. The latest period was more thoroughly studied using optical satellite images acquired almost every year. The importance of glacier morphology and hypspmetry, as well as fjord bathymetry and topography is analyzed. Large glacier systemswith low slopes terminating in deeper waters are retreating faster than small steep glaciers ter− minating in shallower water. A relation between mean annual air temperature and aerial retreat rate of tidewater glaciers was found for long time scales. A sudden temperature in− crease, known as the early 20th century warming in Svalbard, and an increase in temperatures during recent decades are well reflected in deglaciation rate. Influence of sea water temperatures on calving and retreat of glaciers was considered and is significant in short−time intervals of the last decade. Surge events are non−climatic factors which com− plicate the record. They are reflected in front advance or fast retreat due to a massive calving depending on the relation between ice thickness and water depth. Despite the influence of many factors, the response of tidewater glaciers to climate change is evident. The average linear retreat rate of all the tidewater glaciers in Hornsund amounted to ~70 ma−1 in 2001-2010 and was higher than the average retreat of other Svalbard tidewater glaciers (~45 ma−1). Thus, glaciers of this basin can be considered as more sensitive to climate than glaciers of other regions of the archipelago.

Open access

Piotr Zagórski, Jan Rodzik, Mateusz Moskalik, Mateusz C. Strzelecki, Michael Lim, Małgorzata Błaszczyk, Agnieszka Promińska, Grzegorz Kruszewski, Anna Styszyńska and Artur Malczewski

Abstract

A section of a gravel-dominated coast in Isbjørnhamna (Hornsund, Svalbard) was analysed to calculate the rate of shoreline changes and explain processes controlling coastal zone development over last 50 years. Between 1960 and 2011, coastal landscape of Isbjørnhamna experienced a significant shift from dominated by influence of tide-water glacier and protected by prolonged sea-ice conditions towards storm-affected and rapidly changing coast. Information derived from analyses of aerial images and geomorphological mapping shows that the Isbjørnhamna coastal zone is dominated by coastal erosion resulting in a shore area reduction of more than 31,600 m2. With ~3,500 m2 of local aggradation, the general balance of changes in the study area of the shore is negative, and amounts to a loss of more than 28,000 m2. Mean shoreline change is −13.1 m (−0.26 m a−1). Erosional processes threaten the Polish Polar Station infrastructure and may damage of one of the storage buildings in nearby future.