Spatial and Temporal Influences of Thermokarst Failures on Surface Processes in Arctic Landscapes

Recent summaries of international research clearly document the past and future extent of climate warming in the Arctic. These summaries suggest that in the future, rising temperatures will be accompanied by increased precipitation, mostly as rain: 20% more over the Arctic as a whole and up to 30% more in coastal areas during the winter and autumn. These climate changes will have important impacts on arctic systems. Of direct interest to this project is the likelihood that warming will promote permafrost degradation and thaw. Formerly frozen soils may be further destabilized by increased precipitation, leading to hillslope thermokarst failures. We have recently documented that thermokarst failures are abundant and appear to have become more numerous around Toolik Lake on the eastern North Slope and in the western Noatak River basin in Alaska. We expect that a widespread and long-term increase in the incidence of thermokarst failures will have important impacts on the structure and function of arctic headwater landscapes. This project takes a systems approach to address hypotheses about how thermokarst failures influence the structure and function of the arctic landscape. Specifically we are quantifying the composition of vegetation, the distribution and processing of soil nutrients, and exports of sediments and nutrients to stream and lake ecosystems. We are using a combination of field experimentation, remote sensing, and simulation modeling as a means to quantify these relationships. In related objectives we are linking results obtained at this hillslope scale to patterns observed at the landscape scale to test hypotheses about the spatial distribution of thermokarst failures in the arctic foothills. We are beginning to work with native communities to determine the linkages between relatively recent observations based on technical data and local knowledge based on community experience, and to correlate the rate of thermokarst occurrence with long-term climate oscillations and indices. We contend that it is important to understand these interactions because perhaps the greatest potential impacts of changing land surface processes and formation of thermokarst failures are feedbacks to the climate system through energy, albedo, water, and trace gas exchange. This presentation will report highlights from the first (2009) field season of this project, which focused on thermokarst features in the Toolik Lake region, North Slope, Alaska, USA.