Calving waves impact morphodynamics of Arctic beaches, Greenlandic and Svalbard cases studies

Ongoing climate warming is leading to rapid changes in the Arctic environment, including major changes in the cryosphere. One of the effects of recent rapid retreat of marine-terminating glaciers is the exposure of new coastlines. The calving of such glaciers often produces tsunami-like waves that pose a serious threat to coastal environments. These powerful waves are not only able to shift glacial melange in front of ice cliffs and redistribute icebergs, but also flood and rebuild local cliffs and beaches. We present a multidecadal analysis of changes of the coastal zone in front of the Eqip Sermia glacier (Greenland) and Hansbreen (Svalbard). We provide evidence that calving waves play a important role in transforming the lateral moraine left on shore by retreating glacier into a system of beaches and spits. In case of Eqip Sermia part of the former moraine has been transformed into a boulder-dominated spit that has closed the local lagoon over the years. Even one standard calving wave can remodel the beach surface by entraining boulders up to 1.8 m in diameter and eroding the beach surface by leaching sand and gravel from rocky outcrops. Calving waves produced by Hansbreen are smaller and had more subtle effect on local beaches. Our study represents an important advance towards understanding paraglacial coastal evolution in regions characterised by rapid marine-terminating glaciers’ retreat.

Funding: The research is supported by the National Science Centre in Poland (project:  ‘GLAVE- transformation of paraglacial coasts by tsunamis - past, present and warmer future’ No. UMO-2020/38/E/ST10/00042).