Warming permafrost in Scandinavia and Svalbard

Three deep boreholes (approx. 100 m) in mountain permafrost were established in Svalbard (Janssonhaugen) and in Scandinavia (Tarfalaryggen and Juvvasshøe) between 1998 and 2001 by the European Union PACE (Permafrost and Climate in Europe) project. These holes form part of a latitudinal transect of boreholes in permafrost through Europe designed for long-term permafrost monitoring. All boreholes show a significant warm-side deviation in their thermal profiles to 70 m depth, which is most likely associated with surface warming during the last decades. Upward extrapolation to the surface of the temperature gradient between 30-20 m depth indicates surface temperature changes with a magnitude of 1.0 °C to 1.5 °C. Results from seven to ten year thermal time-series collected from the three boreholes strongly supports the previous interpretation that most of the anomalies observed in the temperature depth profiles are associated with surface warming. Results from the time-series data show that the permafrost has warmed considerably at all three sites. Significant warming is detectable down to at least 60 m depth and present decadal warming rates at the permafrost surface are in the order of 0.04-0.07 degrees/year, with greatest warming in Svalbard and in northern Scandinavia. The present regional trend shows accelerated warming during the last decade.