University of Alaska Fairbanks
Abstract: Permafrost has received much attention recentlybecause surface temperatures are rising in most permafrost areas of theEarth, which may lead to permafrost thaw. Thawing of permafrost hasbeen observed at the southern limits of the permafrost zone and thiscan lead to changes in ecosystems, in water and carbon cycles, and ininfrastructure performance. If the current trends in climate continue,warming of permafrost will eventually lead to widespread permafrostthawing in the colder permafrost zones. There is however uncertaintyconcerning where this thawing will occur first, the rate of thaw andthe consequences for Arctic, Subarctic and the global natural systems.Examination of past trends in permafrost conditions and distribution(especially during the last glacial-interglacial cycle) can facilitatebetter understanding of the possible rates and pathways of permafrostdegradation in the future. The main reasons for this are: 1) the mainpresent-day features in permafrost distribution both vertically andlaterally were formed during the last 100,000 years and 2) we canexpect that with persistent future climate warming, the firstpermafrost to begin to thaw will be the youngest Little Ice Agepermafrost, followed by mid- and late-Holocene permafrost, and last tothaw would be the Late Pleistocene permafrost. This presentation willdescribe our knowledge of permafrost development in Eurasia during thelast glacial-interglacial cycle.
To characterize the thermal state of permafrost, the InternationalPermafrost Association launched its International Polar Year Project #50, Thermal State of Permafrost (TSP). Ground temperatures are measuredin existing and new boreholes within the global permafrost domain overa fixed time period in order to develop a snapshot of permafrosttemperatures in both time and space. This data set will serve as abaseline against which to measure changes of near-surface permafrosttemperatures and permafrost boundaries, to validate climate modelscenarios, and for temperature reanalysis. The first results of theproject based on data obtained from North America and Northern Eurasiaare presented. Most of the observatories show a substantial warmingduring the last 20 years. The magnitude of warming varied withlocation, but was typically from 0.5 to 2°C at the depth of zeroseasonal temperature variations in the permafrost. Thawing of theLittle Ice Age permafrost is on-going at many locations. There are someindications that the late-Holocene permafrost started to thaw at somespecific undisturbed locations in the European Northeast, in theNorthwest Siberia, and in Alaska. Projections of possible changes inpermafrost during the 21st century based on application of calibratedpermafrost models are presented. The possible consequences ofpermafrost degradation are also discussed.