High Arctic Paraglacial Coastal Evolution in Northern Billefjorden, Svalbard

Abstract

Mateusz Strzelecki
High Arctic Paraglacial Coastal Evolution in Northern Billefjorden, Svalbard
In contrast to mid and low latitude coasts, relatively little is known regarding the potential impacts of climate and sea-level change on cold region coastal margins. This is an important area of research given the pace of recent climate change and future predictions. Svalbard provided a superb location to quantify how High Arctic coasts are responding to climate warming and the associated paraglacial landscape transformation. The geographical focus for the thesis is Petuniabukta and Adolfbukta, the northernmost bays of Billefjorden, central Spitsbergen. The study area has a sheltered location, a semi-arid, sub-polar climate, limited wave fetch and tidal range, and rapid retreat rate of all surrounding glaciers. Using a combination of geomorphological, sedimentological, remote sensing and dating methods, the thesis investigates the processes that control coastal evolution over annual, century and millennial timescales.
Interannual changes observed between 2008 and 2010 show that High Arctic gravel-barriers are resilient to the impact of local storms and the operation of sea-ice processes. The results of a Schmidt Hammer test demonstrate a significant reduction in rock resistance with decreasing distance from the modern shoreline. Shoreline changes since the end of the Little Ice Age (late 19th/early 20th century) reflect a dramatic increase in sediment supply associated with retreating local ice masses, a shortened winter sea-ice season and melting of permafrost. A new approach of dating of juvenile marine molluscs found in uplifted raised beaches enables the development of a new model of relative sea-level change in the study area.
The thesis demonstrates that existing models of paraglacial coastal evolution, developed on mainly temperate latitude coasts, are not applicable to the High Arctic. Whilst the fundamental importance of the sediment supply and relative sea-level is noted, in the High Arctic these processes are modified by climate-driven factors that influence sediment delivery from terrestrial sources, the extent of sea-ice, permafrost as well as river discharge and slope stability. A new model of paraglacial coastal evolution is proposed that captures these processes and recognises the importance of bedrock topography as a key control on landforms preservation.