Increase in Arctic coastal erosion and its sensitivity to warming in the twenty-first century

Arctic coastal erosion damages infrastructure, threatens coastal communities and releases organic carbon from permafrost. However, the magnitude, timing and sensitivity of coastal erosion increase to global warming remain unknown. Here we project the Arctic-mean erosion rate to increase and very likely exceed its historical range of variability before the end of the century in a wide range of emission scenarios. The sensitivity of erosion to warming roughly doubles, reaching 0.4–0.8 m yr −1 °C −1 and 2.3–4.2 TgC yr −1 °C −1 by the end of the century. We develop a simplified semi-empirical model to produce twenty-first-century pan-Arctic coastal erosion rate projections. Our results will inform policymakers on coastal conservation and socioeconomic planning, and organic carbon flux projections lay out the path for future work to investigate the impact of Arctic coastal erosion on the changing Arctic Ocean, its role as a global carbon sink, and the permafrost–carbon feedback. Coastal erosion in the Arctic is caused by permafrost thaw and wave abrasion enhanced by sea ice melt, both of which will increase under climate change. Projections of erosion rate across the Arctic indicate that mean erosion rates will rise beyond historical precedent over the twenty-first century.