Patterns of Discontinuous Permafrost Thaw in Peatlands

Though rates of permafrost loss and landscape change have been widely documented based on remote sensing and field measurements, the local mechanisms of permafrost degradation remain under-studied. Data collected over three decades of research in the Scotty Creek study basin in the southern Northwest Territories of Canada was analyzed to find vertical conduction accounts for most vertical permafrost degradation, while advective processes are needed to describe thaw in features which are subject to seasonal flows.

It was found that heat advection was necessary to describe lateral thaw rates, which are up to an order of magnitude greater than vertical thaw. Thaw from below, driven either by the geothermal gradient or groundwater flow, may account for up to 10 cm of permafrost thaw annually. Once these thaw mechanisms were established, the hydrologic, thermodynamic and geophysical function of taliks in different parts of the landscape were considered in light of the data collected at the and surrounding area.