New coasts emerging from the retreat of Northern Hemisphere marine-terminating glaciers in the 21st century

Accelerated climate warming has caused the majority of marine-terminating glaciers in the Northern Hemisphere to retreat significantly during the 21st century. While glacier retreat and changes in mass balance are widely studied on a global scale, the impacts of deglaciation on adjacent coastal geomorphology is often overlooked. We examined changes in proglacial zones of marine-terminating glaciers across the Northern Hemisphere in period 2000-2020 to provide a complete GIS dataset of new coastline released from glacial ice on the hemisphere during that time as well as coastline lost due to glacier advance. We identified a total of 2466 ± 0.8 km of new coastline, giving an average length of 123 km every year. Two-thirds of this coastline was exposed in Greenland. At the same time, only 53.1 ± 0.1 km of coastline present in 2000 was covered by glaciers in 2020. We analyse the results by region and compare them with retreat areas of the corresponding glaciers. Additionally, we identified 35 new islands larger than 0.5 km² that were completely uncovered or which lost their glacial connection with the mainland during the period 2000-2020. Finally, we characterize these juvenile coasts by rock type, recent climatic conditions and location in particular permafrost zone. These environmental factors affect recently initiated paraglacial coastal evolution and enable to show hotspots in terms of expected geomorphological coastal dynamics.

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).