Air warming trends linked to permafrost warming in the sub-Arctic catchment of Tarfala, Sweden

Recent ground temperature records from the 100-m-deep borehole near the Tarfala Research Station in northern Sweden reveal that permafrost is warming at a pace consistent with the rate of measured air temperature increase at the site. Here we investigate whether air temperature increase is the main driver of the observed change in the permafrost thermal regime using a non-isothermal hydrogeological numerical model for partially frozen ground. The local site is investigated with different ground surface temperature scenarios representing different integrated effects of surficial heat attenuation processes. Results indicate that despite a short-term sensitivity to heat attenuation processes including snow conditions, the main driver of change in the permafrost thermal regime during the past decade is warming air temperatures. Additionally, the approach used here is shown to be particularly pertinent for modelling warming trends, despite limited prior knowledge of site-specific conditions and geological properties. Understanding the main driving mechanisms of changing permafrost is useful for assessing the suitability of borehole temperature records as proxies for past environmental conditions as well as for modelling possible future climatic impacts.Keywords: Permafrost; warming ground; PACE borehole; numerical modelling; climate change.(Published: 29 September 2016)To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 28978, http://dx.doi.org/10.3402/polar.v35.2897