Permafrost temperatures are an extremely sensitive indicator of climatic change. Changes too small to be detected by continuous measurements of the surface energy budget occur as clear and robust changes in permafrost temperature profiles. This award supports research to allow rational utilization of permafrost temperature data and to improve current interpretations of permafrost temperature profiles. These tasks require a better understanding of the influence of the active layer and snow cover on the thermal regime of permafrost. The research program consists of field and laboratory measurements, interpretation, and modeling the thermal response of permafrost to changes in climate. This research will be conducted at four established sites along the Haul Road between the Brooks Range and Prudhoe Bay. Measurements will include daily temperatures at eleven levels from the air 1/2m or more into the permafrost, annual permafrost temperatures to depths of 80m, in situ and laboratory measurements of thermal and other properties of the numerical model for predicting temperatures at all levels. This continuing research effort is necessary to develop an understanding of climatic change that has occurred and may be occurring in the permafrost areas of Alaska and the north polar region.