Assessment of the permafrost changes in the 21st century and their impact on infrastructure in the Alaskan Arctic

Abstract:

Thawing and freezing of Arctic soils is affected by many factors, with air temperature, vegetation, snow accumulation, and soil moisture among the most significant. Here, we employ the permafrost module of the Alaska Integrated Ecosystem Model (AIEM) and establish several high spatial resolution (1km x 1km) and very high resolution (30m x 30m) scenarios of changes in permafrost characteristics in the Alaskan Arctic in response to projected climate change. Impact of these changes in permafrost on northern Alaskan ecosystems and infrastructure are assessed and regional maps of the possible impacts are developed.

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).