The thermal regime and stability of permafrost in sloping terrain - observations and numerical modelling

Abstract

Ongoing climate change is impacting permafrost environments worldwide, causing a rise in ground temperatures and deepening of the active layer. These changes influence the stability of the ground, especially through their effect on ground ice content. Consequences include ground displacements such as subsidence of the ground surface, slope failures and coastal erosion. This doctoral thesis investigates this complex system interaction based on both field observations and numerical modelling. Field observations on Svalbard show that the thermal regime of permafrost is dependent on local factors, such as the proximity to the sea. Furthermore, erosion of the coastal cliffs on the Brøgger peninsula has increased in recent years, a trend likely be attributable to changing climatic conditions. Numerical models are a simplification of the complex natural conditions, but contribute to our understanding of the underlying processes. Within this doctoral thesis, a new model scheme is developed that (i) computes a modified surface energy balance for sloping terrain, (ii) accounts for ground ice formation and thaw and (iii) performs a slope stability analysis. By coupling this model to atmospheric data, it is possible to evaluate the climate-dependency of ground ice formation and thaw in regions with permafrost, as well as slope stability in permafrost environments.