Lateral thermokarst patterns in permafrost peat plateaus in northern Norway

• Published in: The cryosphere 2021-07, Vol.15 (7), p.3423-3442
• Main Authors: Martin, Léo C. P, Nitzbon, Jan, Scheer, Johanna, Aas, Kjetil S, Eiken, Trond, Langer, Moritz, Filhol, Simon, Etzelmüller, Bernd, Westermann, Sebastian
• Format: Article
• Language: English
• Subjects: Analysis; Boreal ecosystems; Carbon; Climate; Climate change; Depth; Earth Sciences; Environmental degradation; Fluxes; Hydrology; Land surface models; Mathematical models; Microtopography; Modelling; Numerical models; Organic carbon; Peat; Peat-bogs; Peatlands; Permafrost; Photogrammetry; Plateaus; Precipitation; Robustness (mathematics); Sciences of the Universe; Sensitivity analysis; Simulation; Snow; Snow accumulation; Snow depth; Spatial variability; Spatial variations; Stability; Subsidence; Subsurface water; Surface temperature; Surveying; Thermokarst; Topography; Water, Underground
• ISSN: 1994-0424; 1994-0416; 1994-0424; 1994-0416
• DOI: 10.5194/tc-15-3423-2021

Subarctic peatlands underlain by permafrost contain significant amounts of organic carbon. Our ability to quantify the evolution of such permafrost landscapes in numerical models is critical for providing robust predictions of the environmental and climatic changes to come. Yet, the accuracy of large-scale predictions has so far been hampered by small-scale physical processes that create a high spatial variability of thermal surface conditions, affecting the ground thermal regime and thus permafrost degradation patterns. In this regard, a better understanding of the small-scale interplay between microtopography and lateral fluxes of heat, water and snow can be achieved by field monitoring and process-based numerical modeling. Here, we quantify the topographic changes of the SuoÅ¡Å¡jávri peat plateau (northern Norway) over a three-year period using drone-based repeat high-resolution photogrammetry. Our results show thermokarst degradation is concentrated on the edges of the plateau, representing 77 % of observed subsidence, while most of the inner plateau surface exhibits no detectable subsidence. Based on detailed investigation of eight zones of the plateau edge, we show that this edge degradation corresponds to an annual volume change of 0.13±0.07 m.sup.3 yr.sup.-1 per meter of retreating edge (orthogonal to the retreat direction).