Towards a Monitoring Approach for Understanding Permafrost Degradation and Linked Subsidence in Arctic Peatlands

• Published in: Remote Sensing
• Main Authors: Betsabe de la Barreda-Bautista, Doreen S. Boyd, Martha Ledger, Matthias B. Siewert, Chris Chandler, Andrew V. Bradley, David Gee, David J. Large, Johan Olofsson, Andrew Sowter, Sofie Sjögersten
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: permafrost; peatland; InSAR; Science; Q; Arctic; palsa
• Online Access: https://doi.org/10.3390/rs14030444; https://doaj.org/article/2e6251202f494dd08d2d5e44e97e4c3c

Permafrost thaw resulting from climate warming is threatening to release carbon from high latitude peatlands. The aim of this research was to determine subsidence rates linked to permafrost thaw in sub-Arctic peatlands in Sweden using historical orthophotographic (orthophotos), Unoccupied Aerial Vehicle (UAV), and Interferometric Synthetic Aperture Radar (InSAR) data. The orthophotos showed that the permafrost palsa on the study sites have been contracting in their areal extent, with the greatest rates of loss between 2002 and 2008. The surface motion estimated from differential digital elevation models from the UAV data showed high levels of subsidence (maximum of −25 cm between 2017 and 2020) around the edges of the raised palsa plateaus. The InSAR data analysis showed that raised palsa areas had the greatest subsidence rates, with maximum subsidence rates of 1.5 cm between 2017 and 2020; however, all wetland vegetation types showed subsidence. We suggest that the difference in spatial units associated with each sensor explains parts of the variation in the subsidence levels recorded. We conclude that InSAR was able to identify the areas most at risk of subsidence and that it can be used to investigate subsidence over large spatial extents, whereas UAV data can be used to better understand the dynamics of permafrost degradation at a local level. These findings underpin a monitoring approach for these peatlands.