Thermal characteristics and impact of climate change on mountain permafrost in Iceland

[1] This study contains the first quantitative description of mountain permafrost in Iceland, obtained through analysis of four ground temperature time series from recently established shallow boreholes at high altitude (∼900 m above sea level) in central and eastern Iceland. Permafrost is present at three of the four boreholes, where temperatures range from −2° to 0°C. During the data-logging period, 2004–2006, the thickness of the active layer at the individual sites varied between less than 2 m and more than 5 m, mainly owing to differences in near-surface ice content. The ground temperature profiles are nonlinear, with near-surface temperature perturbations considered to be related to a recent warming of the ground surface. At the one nonpermafrost site the insulating influence of winter snow cover is more pronounced. A one-dimensional heat-conduction model was calibrated using ground temperature measurements and driven by surface temperature time series. The model results reproduce the measured ground temperature pattern well. This simplified model, simulating the results of possible future climate scenarios, indicates that permafrost degradation will occur at these sites within decades, depending on climate scenarios chosen and subsurface ice content.