Conference Agenda

Topics:

• Differential interferometric SAR (DInSAR)

• Permafrost, retrogressive thaw slumps, and coastal erosion

ABSTRACT (Abstract + references maximum 1000 words)

Periglacial coasts are degrading due to thermo-abrasive and thermo-denudative processes acting on permafrost [1]. This not only reshapes coastal geomorphology but also enhances nearshore nutrient input and microbial activity, which in turn mobilises organic carbon, part of which is released into the atmosphere as greenhouse gases [2]. With an estimated 1,035 Pg of carbon stored in permafrost worldwide [3] and roughly 34 % of the world’s coastlines underlain by permafrost [4], such degradation has far-reaching implications for the global climate. Yet, the mechanisms that drive coastal erosion, particularly abrupt thaw processes such as retrogressive thaw slumps (RTS), remain poorly understood.

This study aims to improve the understanding of permafrost coastal erosion dynamics, and in particular addresses the question: How can interferometric SAR time-series be used to explain spatial and temporal patterns of surface deformation associated with coastal permafrost degradation and retrogressive thaw slump activity?

The research question is approached by combining differential interferometric SAR (DInSAR) time-series analysis, with geomorphological and thermal covariates. The study focuses on Herschel Island (Qikiqtaruk), Yukon Coast, Canada – a key site for monitoring coastal permafrost degradation in the southern Beaufort Sea [5]. Using multi-temporal TerraSAR-X data (2020–2024), differential InSAR (DInSAR), small baseline subset (SBAS), and 2D inversion techniques were applied to derive millimetre- to centimetre-scale vertical and horizontal surface displacements. Multipolarimetric signatures from the X-band acquisitions were further utilised to infer surface scattering differences.

These deformation patterns were analysed in relation to coastal erosion and retrogressive thaw slump attributes derived from TanDEM-X differential digital elevation models (dDEMs) [6]. The dDEMs were further used to estimate eroded sediment volumes and soil organic carbon (SOC) losses following the approach of [7]. The deformation patterns and dDEMs were additionally compared with environmental covariates such as air temperature, land surface temperature (LST), geomorphology, and vegetation indices to assess how these factors influence RTS behaviour and coastal stability.

By resolving multi-year deformation trends and linking them to geomorphological features, this work contributes to a quantitative understanding of permafrost coastal instability. It highlights the potential of combining radar interferometry with environmental covariates to characterise the spatio-temporal evolution of coastal permafrost degradation – an essential step towards predicting future Arctic coastal responses under continued climate warming.

REFERENCES

[1] Günther, F., Overduin, P. P., Sandakov, A. V., et al.: Thermo-erosion along the Yedoma Coast of the Buor Khaya Peninsula, Laptev Sea, East Siberia, in Proceedings of the Tenth International Conference on Permafrost, Volume 1: International Contributions, Salekhard, Russia, 25–29 June 2012, 137–142, 2012.

[2] Couture, N.: Fluxes of soil organic carbon from eroding permafrost coasts, in Canadian Beaufort Sea, McGill University, 2010.

[3] Hugelius, G., Strauss, J., Zubrzycki, S., et al.: Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps, in Biogeosciences, 11, 6573–6593, https://doi.org/10.5194/bg-11-6573-2014, 2014.

[4] Lantuit, H., Overduin, P.P., Couture, N. et al.: The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines, in Estuaries and Coasts 35, 383–400, https://doi.org/10.1007/s12237-010-9362-6, 2012.

[5] Obu, J., Lantuit, H., Myers-Smith, I., et al.: Effect of terrain characteristics on soil organic carbon and Total nitrogen stocks in soils of Herschel Island, Western Canadian Arctic, in Permafrost and Periglacial Processes, 28 (1), 92–107, https://doi.org/10.1002/ppp.1881, 2017.

[6] Maier, K., Bernhard, P., Ly, S., et al.: Detecting mass wasting of Retrogressive Thaw Slumps in spaceborne elevation models using deep learning, International Journal of Applied Earth Observation and Geoinformation, 137, 1569-8432, https://doi.org/10.1016/j.jag.2025, 2025.

[7] Ramage, J. L., Irrgang, A. M., Morgenstern, A., et al..: Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean, in Biogeosciences, 15, 1483–1495, https://doi.org/10.5194/bg-15-1483-2018, 2018.