9423426 Osterkamp This award supports a study of discontinuous permafrost in northern Alaska. Permafrost exists in arctic and subarctic regions where changes in climate are most likely to be largest and to occur first. Warm discontinuous permafrost will be the first to thaw in the event of any climatic warming. Climatic data indicate that Alaska is currently warming at a rate of about 2.4 C per century. Data has been obtained which shows that the discontinuous permafrost south of the Yukon river in Alaska has recently warmed by as much as 1.5 C and that some of it is already thawing. The objective of this research is to develop a better understanding of the response of discontinuous permafrost to changes in climate and human activities. The significance of permafrost in the context of climatic change studies is that permafrost can detect and record climatic changes in its thermal regime. In thawing, it can act as an agent of environmental changes that influences ecological and human communities and it can amplify climatic change by feedback effects associated with the release of carbon stored in the permafrost. This research includes analyses and interpretations of an extensive long-term (18 years) data set obtained at more than a dozen sites representing a wide range of environmental conditions that span the discontinuous permafrost zone along a north-south transect of Alaska, measurements of current conditions, and assessing changes that have occurred and those that are still occurring. Six sites will be instrumented to measure temperatures in the air, active layer, and permafrost, moisture contents (including unfrozen water), thermal parameters, snow cover and active layer characteristics, and heave. Less detailed measurements will be made at eight other sites. This research will also include an investigation of temporal and spatial trends in the data, the flow of heat and moisture (including several existing hypotheses), and the application of an analyti cal model and of two existing numerical models for predicting the thermal regime and talik development in warm and thawing permafrost. A sensitivity analysis will be carried out on the effects of changes in climatic variables and active layer characteristics on the thermal regime of the discontinuous permafrost.
