Assessment of the permafrost changes in the 21st century under various disturbances to the land cover in the Alaskan Arctic

Thawing and freezing of Arctic soils is affected by many factors, with air temperature, vegetation, snow accumulation, and soil moisture among the most significant. In this research, we employ the transient permafrost dynamics model developed at the Geophysical Institute Permafrost Laboratory (GIPL) and simulate several high spatial resolution (1km x 1km) scenarios of changes in permafrost characteristics in the Alaskan Arctic in response to projected climate change and to land surface disturbances commonly occurring during various construction phases. Impact of these changes in permafrost on northern Alaskan ecosystems and infrastructure are assessed and regional maps of the possible impacts are developed. A map of the potential land subsidence due to the permafrost degradation is presented. The GIPL-2 numerically simulates soil temperature dynamics and the depth of seasonal freezing and thawing by solving the 1-D non-linear heat equation with phase change. In this model the processes of soil freezing and thawing are occurring in accordance with the volumetric unfrozen water content curve and soil thermal properties. The snow temperature and thickness dynamics are simulated assuming the snow accumulation, compaction and phase change processes. We validate our model simulations by comparing with available active layer, permafrost temperature and snow depth records from existing permafrost observatories operated by USGS and the Geophysical Institute of UAF in the North Slope region. Properties of surface vegetation, soil type, layering and moisture content are up-scaled using the Ecosystems of Northern Alaska map (Jorgenson and Heiner, 2003).