Assessment Of High Temperature Permafrost Thaw Infiltration And Land Subsidence Under Long-term Climate Change

The temperature has been warming at a faster rate than the rest of the world in Arctic Alaska,resulting in the increased growing season and shortened snow cover season.Past studies found climate warming and anthropogenic activities led to permafrost degradation,causing a widespread impact on the built infrastructure,such as roads,airports,and pipelines,and threaten their safe operation in the broad cold regions.Such problems are particularly severe in areas where thaw-unstable warm permafrost exists extensively.This study attempts to assess the climate change influence on the thermal state of warm permafrost and its potential impact on the built infrastructure.A highway in Bethel,Alaska,located in deep,warm permafrost in western Alaska,was chosen as the study site.Characteristics of the near-surface air temperature predictions from 31 climate models in the fifth phase of the Coupled Model Intercomparison Project were analyzed.The air freezing and thawing indices were evaluated from the climate modeling results and compared with historical data.Thermal models of the selected ice-rich and ice-poor profiles were built and used to assess warm permafrost degradation during the next century.Thermal models included three temperature scenarios(i.e.,mean,high,and low)and two different ground covers(i.e.,asphalt pavement,and tundra and vegetation).Results,including predicted permafrost thaw and settlement and its potential impact on the built transportation infrastructure,were discussed.The predicted air temperature shows an accelerated warming trend,resulting in a steady increase in the predicted thaw penetration and settlement.Thermal model results indicated permafrost thaw penetration and settlement were primarily dependent on climate changes,ground cover conditions,and thermal properties conditions.Significant differential settlement is predicted between ice-rich and ice-poor profiles,resulting in a severe impact on the built infrastructure,such as buried utilities,roadways,buildings,and bridges.