Consequences of permafrost degradation for Arctic infrastructure – bridging the model gap between regional and engineering scales

• Published in: The Cryosphere
• Main Authors: T. Schneider von Deimling, H. Lee, T. Ingeman-Nielsen, S. Westermann, V. Romanovsky, S. Lamoureux, D. A. Walker, S. Chadburn, E. Trochim, L. Cai, J. Nitzbon, S. Jacobi, M. Langer
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: geo; envir; Arctic; Talik; Ice; permafrost; The Cryosphere; Tundra; Alaska
• Online Access: https://doi.org/10.5194/tc-15-2451-2021; https://tc.copernicus.org/articles/15/2451/2021/tc-15-2451-2021.pdf; https://doaj.org/article/193d2b8a6c154abf8ab05139a8e16cd0

Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate-warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally coupled 1D heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilisation due to talik formation in the ground beside the road rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-Arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-affected permafrost ground. Our model results suggest that current ...