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This paper provides a review of permafrost modelling advances, primarily since the 2003 permafrost conference in Zürich, Switzerland, with an emphasis on spatial permafrost models, in both arctic and high mountain environments. Models are categorised according to temporal, thermal and spatial criteria, and their approach to defining the relationship between climate, site surface conditions and permafrost status. The most significant recent advances include the expanding application of permafrost thermal models within spatial models, application of transient numerical thermal models within spatial models and incorporation of permafrost directly within global circulation model (GCM) land surface schemes. Future challenges for permafrost modelling will include establishing the appropriate level of integration required for accurate simulation of permafrost‐climate interaction within GCMs, the integration of environmental change such as treeline migration into permafrost response to climate change projections, and parameterising the effects of sub‐grid scale variability in surface processes and properties on small‐scale (large area) spatial models. Copyright © 2008 John Wiley & Sons, Ltd.

Active-layer thickness was mapped over a 26,278-km2 area of northern Alaska containing complex and highly variable patterns of topography, vegetation, and soil properties. Procedures included frequent probing to ascertain thaw depth in representative land-cover units, extensive thermal monitoring with data loggers, and application of spatial analytic techniques. Geographic information systems technology was used analytically to merge thaw-depth and temperature data with a digital land-cover map, a digital elevation model, and a topoclimatic index, yielding a spatial time series of active-layer thickness for the map area at weekly intervals over the summer of 1995. Although the maps show a strong regional trend in the thickness of the active layer, extreme local variation occurs in complex terrain and in areas with sharp discontinuities in soil moisture content. Because active-layer thickness is influenced strongly by vegetation and soil properties, the relative volume of thawed soil beneath several landscape units is not proportional to the relative surface area occupied by those units. Predicted values of active-layer thickness are within approx. 6 cm of measured mean values in representative 1-km units distributed over the latitudinal extent of the study area. If computed and averaged for a series of years (e.g, one decade), the integrated products yielded by the mapping procedures could be used as baseline documents for comparison with calculations based on climate-change simulations.

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