Acceleration of coastal-retreat rates for high-Arctic rock cliffs on Brøggerhalvøya, Svalbard, over the past decade

• Main Authors: J. Aga, L. Piermattei, L. Girod, K. Aalstad, T. Eiken, A. Kääb, S. Westermann
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2024
• Subjects: Dynamic and structural geology; QE500-639.5; Arctic; Brøggerhalvøya; Canadian Arctic Archipelago; Svalbard; Arctic Archipelago; Sea ice
• Online Access: https://doi.org/10.5194/esurf-12-1049-2024; https://doaj.org/article/3d76108285aa482295fb0c47fcab324b

In many Arctic regions, marine coastlines change rapidly in our currently warming climate. In contrast, coastal rock cliffs on Svalbard are considered to be relatively stable. Long-term trends of coastal-retreat rates for rock cliffs on Svalbard remain unknown, but quantifying them could improve our understanding of coastal dynamics in the Canadian Arctic Archipelago. This study presents coastal-retreat rates for rock cliffs along several kilometres of Brøggerhalvøya, Svalbard. The analysis relies on high-resolution orthoimages from 1970, 1990, 2010, and 2021. The data are corroborated by high-precision dGNSS (differential Global Navigation Satellite System) measurements obtained along selected segments of the coastline. Our analysis reveals statistically significant acceleration in coastal-retreat rates across Brøggerhalvøya between 2010 and 2021. The northeast-facing coastline features fairly stable conditions, with retreat rates of 0.04 ± 0.06 m a −1 (1970–1990; calculated retreat rate ± the corresponding measurement uncertainty), 0.04 ± 0.04 m a −1 (1990–2010), and 0.06 ± 0.08 m a −1 (2010–2021). Along the southwest-facing coastline, higher retreat rates of 0.26 ± 0.06 m a −1 (1970–1990), 0.24 ± 0.04 m a −1 (1990–2010), and 0.30 ± 0.08 m a −1 (2010–2021) were calculated. For the most recent decade, this corresponds to an increase of 50 % for the northeast-facing coastline and an increase of 25 % for the southwest-facing coastline. Furthermore, for the northeast-facing coastline, the proportion of the coastline affected by erosion increased from 47 % (1970–1990) to 65 % (2010–2021), while it stayed consistently above 90 % for the southwest-facing coastline. The recent acceleration in retreat rates coincides with increasing storminess and retreating sea ice, factors that can enhance coastal erosion.