Accelerated climate warming has caused the majority of marine-terminating glaciers in the Northern Hemisphere to retreat substantially during the twenty-first century. While glacier retreat and changes in mass balance are widely studied on a global scale, the impacts of deglaciation on adjacent coastal geomorphology are often overlooked and therefore poorly understood. Here we examine changes in proglacial zones of marine-terminating glaciers across the Northern Hemisphere to quantify the length of new coastline that has been exposed by glacial retreat between 2000 and 2020. We identified a total of 2,466 ± 0.8 km (123 km a⁻¹) of new coastline with most (66%) of the total length occurring in Greenland. These young paraglacial coastlines are highly dynamic, exhibiting high sediment fluxes and rapidly evolving landforms. Retreating glaciers and associated newly exposed coastline can have important impacts on local ecosystems and Arctic communities.