The Role of Rapid Glacier Retreat and Paraglacial Landscape Transformation in Controlling the Evolution of High Arctic Coastal Systems

The rapid retreat of glaciers observed since the end of the Little Ice Age (LIA) led to a dramatic transformation of High Arctic landscape. This change is apparent in slope, valley and glacier foreland systems, where glacigenic landforms are being denudated by fluvial, aeolian or mass-wasting processes that are being accelerated by permafrost degradation. However, the impact of these changes on the coastal zone is uncertain because of few studies of pre- and post-LIA coastal change. This paper addresses this deficiency by detailing the patterns and processes of post-LIA coastal zone changes in Svalbard - key area for observation of recent paraglacial landscape change in the High Arctic. By application of a mosaic of geomorphological, sedimentological and remote sensing techniques we proved that studied coastal systems (i.e. Billefjorden, Bellsund, Hornsund) abruptly responded to post-LIA deglaciation, permafrost thaw, extreme slope processes and shifts in glaciated catchments. Most of studied coastal systems were characterised by more rapid morphodynamic adjustments than previously thought. Under intervals characterized by a warming climate, retreating local ice masses and shortened sea-ice seasons most of studied coastal systems rapidly responded to an excess of freshly released sediments and experienced significant geomorphological changes (Figure 1). The increased supply of sediments led to the accumulation of new coastal landforms such as extensive gravel-dominated barriers, spits and tidal flats, which are highly sensitive recorders of recent environmental change. We also proved that the development of the post-LIA Svalbard coast is closely linked to the rate of sediment excavation from relict sediment storage systems, such as alluvial fans and outwash plains, that developed across a wide coast plains between the glacier valleys and the fjord during the Holocene. The results are synthesised to propose a new conceptual model of High Arctic paraglacial coastal system, with the aim of contributing towards a unifying concept of cold region landscape evolution and providing direction for future research regarding the state of High Arctic coastal evolution.This paper is a contribution to the NCN projects UMO2013/11/B/ST10/00283 and UMO2013/08/S/ST10/00585.