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

David Marcolino Nielsen,Victor Brovkin,Tatiana Ilyina,Johanna Baehr,Paul Overduin,Patrick Pieper,Mikhail Dobrynin,Armineh Barkhordarian

doi:10.1038/s41558-022-01281-0

Abstract

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.

Highlights

Arctic coastal erosion is caused by a combination of thermal and mechanical drivers
Arctic coastal erosion rates are expected to increase in the coming decades
Arctic coastal erosion alone releases about as much organic carbon (OC) as all the Arctic rivers combined[23,24], fuelling about one-fifth of Arctic marine primary production[25]

Summary

1: Bykovsky Peninsula and Muostakh Island 2: Mackenzie River Delta region 3

As explained by the three following reasons. First, we assume that the spatial model coefficients, empirically determined, remain unchanged throughout our simulations. The AA factor decreases in magnitude to non-significant values and plays a smaller role in driving erosion in SSP1-2.6 The sensitivities of both the thermal and mechanical drivers of erosion increase at the AA onset (Fig. 4d,e), especially in scenarios SSP24.5 and SSP5-8.5, where they remain significantly positive until the end of the century, as opposed to the historical period. Despite the limitations at reproducing erosion at the local scale, our semi-empirical approach allows us to make pan-Arctic projections of coastal erosion and its associated OC fluxes, and make first-order estimates of the magnitude, timing and sensitivity of their increase to global warming. Online content Any methods, additional references, Nature Research reporting summaries, source data, extended data, supplementary information, acknowledgements, peer review information; details of author contributions and competing interests; and statements of data and code availability are available at https://doi.org/10.1038/ s41558-022-01281-0

42. Alaska Native Villages

Methods

Findings

Code availability