|Résumé||(disponible en anglais seulement)|
In 2011 the Arctic Council directed the Senior Arctic Officials 'to review the need for an integrated assessment of multiple drivers of Arctic change as a tool
for Indigenous Peoples, Arctic residents, governments and industry to prepare for the future'. This resulted in the project 'Adaptation Actions for a Changing Arctic' (AACA; http://www.amap.no/adaptation-actions-for-a-changing-arctic-part-c). AACA is
now moving rapidly. Input from the cryosphere and climate expert community is now needed on the current and future state of the Arctic. To ensure AACA uses the latest knowledge of the climate system there was a need to update selected aspects of the
assessment report 'Arctic Climate Issues 2011: Changes in Arctic Snow, Water, Ice and Permafrost' (SWIPA 2011; http://www.amap.no/swipa), which was published in 2012. The SWIPA update will be based on the latest status on knowledge and will lead to
new stand-alone reports. One of these updates is on permafrost. The SWIPA update on permafrost provides a synthesis of current knowledge across the circumpolar permafrost regions on 1) Thermal state of permafrost 2) Permafrost modeling and
projections of future permafrost states, 3) Permafrost-related processes, coastal erosion, thermokarst and recent changes in thaw lake development, and finally on 4) Cumulative effects of infrastructure and climate change on permafrost and recent
advances in understanding of permafrost-related geo-hazards. Here we present the results from section 1: Thermal State of permafrost. During the International Polar Year (IPY) a snapshot of permafrost thermal state for 2007-09 was developed and
provided a baseline against which future change can be measured. In Canada, Alaska, Russia and Nordic countries measurements of ground temperatures were made in over 575 boreholes representing the range in vegetation, geology and climate found in the
permafrost regions of the Arctic and sub-Arctic (Christiansen et al. 2010; Romanovsky et al, 2010; Smith et al. 2010). In this assessment we provide an updated picture of the current thermal state of permafrost that can be compared to measurements
made during IPY to assess the change that has occurred since IPY. The analyses cover three pilot regions in the Arctic: 1) the Barents Region, 2) Baffin Bay/Davis Strait Region and 3) Bering/Beaufort/Chukchi Region. The longer term records of
permafrost temperatures (time series), more than three decades long for some sites, have also been extended which allows the changes since IPY to be placed within context of the longer record. Since IPY, new record high ground temperatures are
observed at many permafrost observatories across the Arctic. The greatest temperature increase since 2007-09 was more than 0.5°C and was found in the colder permafrost of the Arctic and high Arctic. In warmer permafrost such as that in the southern
and central Mackenzie Valley, in the Alaskan Interior, or in the discontinuous permafrost zone in Siberia and the Nordic region the temperature increase has been much smaller or not detectable. At a few locations permafrost temperature has even
slightly decreased (typically by 0.1°C).
Christiansen, H. H., B. Etzelmüller, K. Isaksen, H. Juliussen, H. Farbrot, O. Humlum, M. Johansson, T. Ingeman-Nielsen, L. Kristensen, J. Hjort, P. Holmlund, A. B. K. Sannel, C. Sigsgaard,
H. J. Åkerman, N. Foged, L. H. Blikra, M. A. Pernosky, and R. Ødegård, 2010: The Thermal State of Permafrost in the Nordic area during the International Polar Year. Permafrost and Periglacial Processes, 21, 156'181.
Romanovsky, V.E., Drozdov,
D.S. Oberman, N.G., Malkova G.V., Kholodov A.L., Marchenko, S.S., Moskalenko, N.G., Sergeev D.O., Ukraintseva, N.G., Abramov A.A., Gilichinsky, D.A., and A.A.Vasiliev, 2010b. Thermal State of Permafrost in Russia. Permafrost and Periglacial
Processes, 21: 136-155.
Smith, S.L., Romanovsky, V.E., Lewkowicz, A.G., Burn, C.R., Allard, M., Clow, G.D., Yoshikawa, K., and Throop, J. 2010. Thermal state of permafrost in North America - A contribution to the International Polar Year.
Permafrost and Periglacial Processes, 21: 117-135.