The role of rapid glacier retreat and landscape transformation in controlling the post‐Little Ice Age evolution of paraglacial coasts in central Spitsbergen (Billefjorden, Svalbard)

Abstract

In Svalbard, the rapid glacier retreat observed since the end of the Little Ice Age (LIA) has transformed the geomorphology and sediment budgets of glacial forelands, river valleys, and slope systems. To date, relatively little information exists regarding the impact of such a profound glacial landscape degradation on the evolution of coastal environment. This paper addresses this deficiency by detailing the post‐LIA sediment fluxes to the coastal zone in Billefjorden, central Spitsbergen (Svalbard). We analysed the response of the gravel‐dominated barrier coast to the decay of Ferdinandbreen, one of the fastest retreating glaciers in the region. Glacier retreat resulted in the development of paraglacial sediment cascade where eroded and reworked glacigenic sediments progressed through alluvial fans to the coast, thus feeding gravel‐dominated spit systems in Petuniabukta. We demonstrated that the coastal systems in central Spitsbergen responded abruptly to post‐LIA climatic changes. The acceleration of coastal erosion and associated spit development was coincident with rapid climate warming that dates from the 1980s and has been associated with longer ice‐free periods and activation of multiple sediment supply sources from the deglaciated landscape. In colder phases of post‐LIA period, coastal zone development was subdued and strongly dependent on the efficiency of sediment transport via in a longshore drift. Finally, we discuss the differences in the post‐LIA coastal responses between central Spitsbergen and western Spitsbergen highlighting the efficiency of paraglacial sediment delivery from land to the coast controlled by the state of glacial systems, bedrock topography, and development of river channels.

New fjords, new coasts, new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund, southern Svalbard)

“…This coastal sector, located at the southern side of Brepollen, is similar to previously observed paraglacial coastal systems in Svalbard, where coasts evolve in response to glaciofluvial sediment pulses released by land-terminating, valley-type glaciers (e.g. Zagórski et al, 2012;Bourriquen et al, 2018;Strzelecki et al, 2018). Rivers draining glacierized catchments of Signybreen, Bautbreen and Noname glacier (covering the northern slopes of Starostinfjellet) are major sediment feeders to the southern Brepollen coast.…”

“…Previous coastal studies in Svalbard have shown the strong relationship between rates of coastal progradation (mainly delta growth) and glaciofluvial activity (e.g. Bourriquen et al, 2016;Strzelecki et al, 2018). Similar observations were made along the coasts of Greenland, where rapid retreat of glaciers not only exposed new lands but also released significant amounts of sediment, leading to progradation of delta systems (Bendixen et al, 2017).…”

“…In most of the coves between Treskelpynten and Breholmen, rocky promontories have provided anchor points for narrow and fragile barriers or spits. As noted by Strzelecki et al (2018), bedrock topography is also one of the key controls on sediment storage capacity in Svalbard coastal plains.…”

“…Previous studies on the evolution of paraglacial coasts in Svalbard have focused predominantly on the interplay between coastal change and glacifluvial sediment supply from retreating land-terminating glaciers (e.g. Mercier and Laffly, 2005;Étienne et al, 2008;Zagórski, 2011;Zagórski et al, 2012;Bourriquen et al, 2018;Strzelecki et al, 2018). In those systems, development of coastal landforms is controlled by the configuration and shifts of river channels, including their hydrology; the presence and accommodation space of intermediary storage areas within the river system, such as braided floodplains, alluvial fans and bedrock basins, that control the efficiency of fluvial sediment supply; and exposure of coasts to the storm waves/open sea.…”

High Arctic coasts at risk—the case study of coastal zone development and degradation associated with climate changes and multidirectional human impacts in Longyearbyen (Adventfjorden, Svalbard)

“…In general, over the last decade, Svalbard coastal studies have been concentrated on the coastal zone response to shifts in sediment supply associated with changes in local ice masses and paraglaciation (e.g., Bourriquen et al, ; Mercier & Laffly, ; Sessford, Strzelecki, & Hormes, ; Strzelecki et al, ; Zagórski, ); ephemeric pulses of sediments from snow‐fed streams (Lønne & Nemec, ; Strzelecki, Long, & Lloyd, ); or the controls of coastal permafrost development (Kasprzak et al, ). Recent years had also brought some advances in local rocky coast systems that dominate over coastal landscape in numerous Svalbard fjords (e.g., Kasprzak et al, ; Strzelecki, ; Strzelecki, ; Strzelecki et al, ; Świrad, Migoń, & Strzelecki, ).…”