Three deep Alpine‐permafrost boreholes in Svalbard and Scandinavia

Abstract

The presence and thermal character of permafrost reflect past and present surface energy balances plus the heat flux from the Earth's interior. Analysis of permafrost ground temperatures constitutes a key research tool for detecting thermal anomalies caused by twentieth‐century warming. Three deep boreholes in alpine permafrost were drilled in Svalbard and Scandinavia and form part of the latitudinal transect of mountain permafrost boreholes through the mountains of Europe established under the EU PACE (Permafrost and Climate in Europe) project. The northernmost borehole in the transect, at Janssonhaugen (depth 102 m), western Svalbard (78°10′46′′N, 16°28′01′′E, 270 m ASL) was drilled in May 1998. In Scandinavia, boreholes were drilled at Tarfalaryggen (depth 100 m), northern Sweden (67°55′09′′N, 18°38′29′′E, 1550 m ASL) in March 2000 and at Juvvasshøe (depth 129 m), southern Norway (61°40′32′′N, 08°22′04′′E, 1894 m ASL) in August 1999. Permafrost thickness at Janssonhaugen is estimated as approximately 220 m. The temperature profiles on Tarfalaryggen and Juvvasshøe show anomalously low geothermal gradients, indicating low heat flow through thick permafrost (∼350 m and ∼380 m respectively). Palaeoclimatic analysis based on inversion modelling of the ground temperature measurements at Janssonhaugen shows near surface warming of 1.5 ± 0.5 °C during the twentieth century. Both the Tarfalaryggen and Juvvasshøe boreholes also reveal thermal anomalies, which reflect a surface warming over the past decades, with a magnitude of approximately 0.5–1.0 °C. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉL'existence d'un pergélisol ainsi que ses caractères thermiques reflètent la balance entre l'énergie de surface (passée et actuelle) et le flux de chaleur interne de la terre. L'étude des températures du pergélisol constitue ainsi une recherche fondamentale pour détecter les anomalies thermiques dues au réchauffement du vingtième siècle. Trois sondages profonds dans le pergélisol alpin ont été réalisés au Svalbard et en Scandinavie. Ils constituent une partie du transect en latitude de sondages du pergélisol de montagne réalisé dans le cadre du projet de l'Union Européenne Pace (Pergélisol et Climat en Europe). Le sondage le plus septentrional du transect a été foré en mai 1998 à Janssonhaugen (profondeur 102 m), à l'ouest de Svalbard (78°10′46′′N, 16°28′01′′E, à 270 m d'altitude). En Scandinavie, des sondages ont été réalisés en mars 2000 à Tarfallaryggen (profondeur 100 m) au nord de la Suède (67°55′09′′N, 18°38′29′′E, à 1550 m d'altitude) et en août 1999 à Juvvasshoe (profondeur 129 m), au sud de la Norvège (61°40′32′′N, 08°22′04′′E, à 1894 m d'altitude). L'épaisseur du pergélisol à Janssonhaugen est approximativement de 220 m. Les profils de température à Tarfalaryggen et à Juvvasshoe montrent des gradients géothermiques anormalement faibles, indiquant un faible écoulement de chaleur au travers d'un pergélisol épais (respectivement d'environ 350 m et 380 m). Des analyses paléoclimatiques basées sur un modèle d'inversion des mesures de la température du sol à Janssonhaugen indiquent un réchauffement près de la surface de 1.5 0.5 °C pendant le 20e siècle. A la fois à Tarfalarygen et à Juvvasshoe, les anomalies thermiques existantes révèlent un réchauffement de la surface d'une ampleur de approximative de 0.5 à 1.0 °C au cours des dernières décades

The thermal state of permafrost in the nordic area during the international polar year 2007–2009

“…All three boreholes show significant warm-side deviations in their thermal profiles down to 70 m depth, which are most likely associated with surface warming during the past decades, with the largest change occurring in the northernmost borehole in Svalbard (cf. Harris et al, 2003;Isaksen et al, 2001). Apart from the absence of any alternative reason for the warming, the similarity of the two thermal profiles from Tarfalaryggen and Juvvasshøe suggest a common cause, that is, warming of the upper permafrost surface (Isaksen et al, 2007b).…”

“…A brief description of the thermal profiles from all three Nordic PACE boreholes was presented by Isaksen et al (2001), and was later compared with all the boreholes in the European PACE permafrost network (Harris et al, 2003(Harris et al, , 2009. Although derivation of climate signals from temperature profiles in mountain permafrost is complicated by three-dimensional effects (e.g.…”

“…Continuous long-term ground temperature monitoring was initiated in the 129 m deep borehole at Juvasshøe (PACE30) in August 1999 Isaksen et al, 2001). A 20 m deep control borehole (PACE31) was drilled 15 m away from the main Juvvasshøe borehole, also in 1999, to avoid the thermal influence of the protection structure located at the upper 4 m of the main borehole .…”

“…At Tarfalaryggen, a mountain pass area at 1550 m a.s.l., ground temperature monitoring was continued in 100 m and 15 m boreholes that were drilled into the bedrock in April 2000 close to the Tarfala Research Station (Table 1, Harris et al, 2001;Isaksen et al, 2001). The site is largely unvegetated and the sediment cover is 4 m thick consisting of weathered bedrock and boulders.…”

Polygon pattern geomorphometry on Svalbard (Norway) and western Utopia Planitia (Mars) using high-resolution stereo remote-sensing data

“…High aridity → sand wedge polygons Péwé (1959);Black (1976);French (2007) Ice-wedge polygon formation Soil temperature, grain size In clay → b−2°C, in gravels → b−6°C Romanovskii (1985) Permafrost thickness ranges from 100 m in the valleys to around 450 m in the mountains (e.g., Liestøl, 1976;Isaksen et al, 2001). Permafrost ages on Svalbard are estimated to be late Holocene in the valleys and the coastal areas (Humlum et al, 2003).…”