Permafrost Modelling and Climate Change Simulations in Northern Sweden

Sammanfattning: Permafrost is an important component in Arctic environments and has been hypothesized to be diminishing due to global warming. A growing concern is that large quantities of stored organic carbon will be mobilized and released to the atmosphere as the potent greenhouse gas methane if the ground thaws. This could result in a massive positive feedback on the global climate change. To quantify this effect, the permafrost extent as well as carbon storages must be mapped. In this study, a Basal Temperature of Snow (BTS) survey is conducted in the Tarfala Valley in Northern Sweden and a model of the current permafrost extent in the region is produced. Additionally, the model explores how the permafrost extent will change under three climate change scenarios at +1°C, +2°C and +4°C. According to a statistical analysis, elevation is the only significant variable for permafrost occurrence in the Tarfala Valley. Currently, continuous permafrost (>0.8 probability) is present at elevations exceeding 1523 m a.s.l. and sporadic or patchy permafrost (<0.5 probability) dominates below 1108 m a.s.l. The permafrost in Northern Sweden is near the boundary of favorable conditions for permafrost, and the greatest decline in permafrost extent occurs during the initial warming. In the +1°C scenario, which will be reached in 20 years if current warming rate is sustained, 97.6% of the continuous permafrost in the Abisko and Tarfala area degrades. The areal extent of the zone with the lowest probability of permafrost occurrence increases from 59% to 90% in the same scenario. Under continued warming to +4°C compared to current ground temperatures, 98% of the study area will be covered by sporadic or patchy occurrences of permafrost.