Glacier surge as a trigger for the fastest delta growth in the Arctic

Abstract The widespread retreat of Svalbard glaciers has been frequently interrupted by short-lived surge advances. In the case of marine-terminating glaciers this is often expressed in the remodelling of coastal zones. Here, we analyzed the coastal zone changes in front of the recently surging Recherchebreen. The glacier advanced ca 1200 m since 2018 and suddenly stopped in June 2020 followed by the rapid formation of a delta system in front of its subglacial meltwater outlet. The delta advanced by ca 450 m with probably the fastest progradation rate ever detected in the Arctic region (ca 7 m/day). The synchroneity of the final slow-down of the glacier with the delta building indicates that this event records the release of stored water and sediments from beneath the glacier and thus provides direct evidence of drainage reorganisation at the termination of a surge. Such behaviour is likely common among Svalbard surging glaciers, but it only rarely leaves any direct geomorphic evidence.