Response of Permafrost to Surface Temperature Changes

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Permafrost temperatures at depth represent a systematic running mean of the temperature history at the permafrost surface. Global changes, such as climatic warming are, or will be, reflected in the permafrost temperature profiles. Recent permafrost temperature measurements show that some Alaskan permafrost has warmed as much as 4 C over the past 50-100 years and limited meteorological data suggest that this warming is directly related to changes in mean air temperature in an area where carbon dioxide warming is predicted to be the greatest. A host of serious environmental and engineering problems that have a substantial impact on the use of polar lands are associated with warmer and/or thawing permafrost. However, data on the thermal regime of permafrost in Alaska are very sparse and mostly unusable because of surface disturbances near the drill holes. This investigation will measure permafrost temperatures at sixteen undisturbed sites along the trans-Alaska pipeline corridor which includes Alaska's three major climate and permafrost zones and at fifteen other widely distributed sites in Alaska. Measurements will include temperatures in the air, at the ground surface, in the active layer, at the permafrost table and in the permafrost to depths of 80 m or more. Interpretation and modeling of these data will be carried out to determine the relationships between temperatures at all levels and the effects of changes in surface temperatures on the permafrost. These studies will contribute to our ability to extract information on past climate from the permafrost temperature profiles. Drilling the holes, the greatest cost of these investigations, has already been completed.