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

The majority of marine-terminating glaciers in the Northern Hemisphere have retreated significantly during the 21st century, in line with the accelerated climate warming trend in the Arctic. While glacial retreat and changes in glacier mass balance are widely studied at a global scale, how deglaciation influences adjacent coastal geomorphology is often overlooked and as a result poorly understood. We analysed changes in proglacial zones of marine-terminating glaciers to quantify the length of new coastline that has been exposed due to glacial retreat between 2000 and 2020. We identified a total of 2466 ± 65 km (123 km a ^− 1 ) of new coastline with most (66%) of the total length appearing in Greenland. These young paraglacial coastlines are highly dynamic and characterized by high sediment fluxes and rapidly evolving landforms. The changes triggered by retreating glaciers and newly exposed coastline can have significant impacts on local ecosystems and communities.