Permafrost

140
Temporal and Spatial Changes of Permafrost Distribution in the Tien
Shan Mountains During the Last Millennia
Sergei Marchenko and Vladimir Romanovsky
(Geophysical Institute, University of Alaska Fairbanks, USA)
Abstract: During the Late Holocene there were numerous periods of warming and cooling in
the Tien Shan Mountains, Central Asia. The dynamics of air and ground surface temperature
changes that occurred in the Tien Shan at an altitude of 2500 m a.s.l. during the last millennium
has been obtained by correlating the data from radiocarbon dates, tree-rings indexes, and
limnological, archeological and historical data. During the last millennium, the most significant
periods of cooling occurred during 1150-1350 and 1600-1850.
Ground temperatures and permafrost area in the Northern Tien Shan have been subject to
repeated fluctuations during the Late Holocene. During the maximum warming, the ground
temperatures rose by approximately 1.0-1.5°C. The altitude oscillations of the permafrost lower
boundary had amplitude of about 200-300 m. The result of numerical simulations shows that
the permafrost formation at an altitude of 2500 m a.s.l. has developed at least two times
during the last millennia.
At the lover boundary of permafrost distribution the permafrost temperatures now are
close to 0°C and at some sites permafrost degradation has already started. Analysis of measured
active layer and permafrost temperatures coupled with numerical thermal modeling (permafrost
temperature reanalysis) shows that most of the recently thawed permafrost was formed during
the Little Ice Age. Since the second part of the nineteenth century, permafrost in the Tien Shan
Mountains is experiencing a warming period, which continues up to the present. The geothermal
observations and modeling indicate that in the Tien Shan more favorable conditions of
permafrost occurrences and preservation exist in the coarse blocky material where the mean
annual temperatures are typically 2.5-4.0°С colder than the mean annual air temperature.
Key words: Climate variability, alpine permafrost, modeling, Tien Shan.
Natural Processes Trend in Russian Permafrost Regions
Stanislav V. Maximovich
(Institute of Physicochemical and Biological Problems in Soil Science, RAS,
Pushchino, Russia, e-mail: svmax@ibbp.psn.ru)
Abstract: The author of this report believes that naturally and anthropogenic disturbed habitats
(waterside slopes, baidzherakhs, quarries, steep mountain slopes with mobile grounds, ground
roads, open cuts, industrial workings, cutting slopes, embankment and dirt roads, and roadsides,
streets of populated localities, etc.) are the most convenient objects for studying trend of recent
natural processes – successions and fluctuations of vegetation, soil forming processes, etc.
Researches have been conducted in Yakutia, in northern territories of Zabaikalye and Amur
regions, near Vorkuta (Komi Republic), Labytnangi – Salechard (Yamal region), Khatanga
(Taymyr region). These are zones of tundra, forest-tundra and taiga. Disturbed habitats of these