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THE ALPINE LANDSCAPE RESPONSE TO THE SPACE-TIME CLIMATE
CHANGES IN THE ALTAI MOUNTAINS
Margarita Syromyatina
Saint-Petersburg State University,
10th line V.O. 33, Saint-Petersburg, Russia
[email protected]
Igor Moskalenko
Saint-Petersburg State University,
10th line V.O. 33, Saint-Petersburg, Russia
[email protected]
Kirill Chistyakov
Saint-Petersburg State University,
10th line V.O. 33, Saint-Petersburg, Russia
[email protected]
Abstract
This research is a part of a big project of the Saint-Petersburg State University (SPbSU) “The
Northern Eurasia mountain geosystems under the global climate changes and the
transformation of the nature management regimes”. The mountain regions, and particularly
the Altai Mountains, are of specific interest due to the relatively low anthropogenic load and
great sensitivity of the mountain landscapes. The current research is a continuation of the
long-term field expeditions and theoretical researches of the SPbSU in the Altai-Sayan
Mountains. The Department of Geography and Geoecology of the SPbSU has been organizing
annual field expeditions to this mountain system during the last 20 years. The regional climate
changes are presented against the background of global climate change including the
atmospheric circulation epochs. The uniqueness of the Altai landscapes lies in their great
variety as these mountains are higher than 4 km and located on the zonal border between
steppes and semi-deserts and between continental and sharply continental climates. The
purpose of the research was to reveal space-time features of regional climate changes and the
reaction of different altitudinal zonation elements to these changes. The 1940-2004 time series
of the seasonal air temperature and precipitation from 14 weather stations were statistically
analyzed applying regression, correlation, spectral and cluster analyses. The analysis of
climate change spatial patterns in the region was made. To extend the time series over the
past 350-400 years, mean summer temperature and precipitation were reconstructed applying
dendroclimatological methods and using the WSL Dendro data base and core samples
received during the field expeditions as well as the treeline position estimates. Comparing to
the Northern Hemisphere the tendency of temperature increase in the second half of the 20th
century over the Altai has been observed generally earlier, since 1950s. The most intense
temperature increase during the last 20-30 years is specific to the most arid part of the region
- South-Eastern Altai. Maximum warming rate in the last quarter of the 20th century is
typical to winter in the Altai (0,85°C/10 years) as well as the entire Northern Hemisphere.
Minimum warming rate is observed in autumn (0,17°C/10 years). Synchronous changes in the
Altai and the entire Northern Hemisphere are observed in all seasons only in 1975-2004 years.
At the turn of the XX-XXI centuries warming rates slow down in the region while the
temperature level is still high. These changes are partly associated with the circulation epochs,
especially in winter. Spectral analysis revealed the important role of natural cyclical
recurrence in climate change in the region, for example quasi-biennial, solar and Brückner
cycles. The dendrochronological reconstruction showed that mean summer temperature
increased from the end of the Little Ice Age (LIA) to its maximum in the 1990s by
approximately 2°C. Finally the climatic conditionality of the altitudinal belt spatial
distribution, treeline and glacier dynamics were estimated. In the Altai almost the full range
of the temperate zone altitudinal belts is presented - from desert steppe to glacial-nival.
Vertical hydrothermal gradients were employed to characterize each altitudinal belt by the
climatic area of distribution (mean summer temperature and annual precipitation ranges). As
treeline against the other belt borders strongly limited by summer temperature (7.5-9°C) its
eventual dynamics were estimated and treeline position at different stages of warming was
reconstructed. Theoretical evaluation shows that mean summer temperature increase of 1.3°C
from the end of the LIA (1860-1880 yrs) to the period of 1986-2004 yrs causes treeline to rise
maximum by 180-280 m in different localities of the Altai Mountains. The results of this
research are used in the prediction of the mountain landscape dynamics, the estimation of the
natural resources potential and the strategy of the mountain region sustainable development.
Introduction
The Russian Altai Mountains are located in the Inner Asia on the border of Russia, Kazakhstan,
China and Mongolia. The uniqueness of the Altai landscapes lies in their great variety as these
mountains are higher than 4 km and are located on the zonal border between steppes and semideserts and between continental and sharply continental climates. In the Altai Mountains almost the
full range of the altitudinal belts of the temperate zone is presented – from desert steppe to glacialnival. Detailed analysis of the air temperature and precipitation time series from the maximum
possible amount of weather stations allows revealing space-time features of regional climate
changes. The dendrochronological analysis was employed to range the tendency of climate changes
over the pre-instrumental period. The analysis of regional climate changes against the background
of global climate change including the atmospheric circulation epochs in the Northern Hemisphere
and the revelation of natural cyclical recurrence make it possible to assume the causes of modern
regional climate change. The sensivity of the Alpine landscapes to climate changes and the need to
obtain reliable geographical predictions make this research of extra relevance. First of all it is
important to make quantitative assessment of the climatic dependence of the mountain landscape
space-time changes. Temperature and precipitation changes result in treeline, snowline, glacier,
avalanching and river runoff dynamics. This research is focuses on the climatic conditionality of the
altitudinal belt spatial distribution and treeline dynamics since the end of the LIA.
Main results
The 1935-2004 time series of the seasonal air temperature and precipitation from the 14 weather
stations (Federal Service for Hydrometeorology and Environmental Monitoring, All Russian
Research Institute of Hydrometeorological Information - World Data Center) from 300 to 2600 m
a.s.l. (Figure 1) were statistically analyzed applying regression, correlation, spectral and cluster
analyses. To compare regional climate change with the global changes were used:
- the air temperature time series from 1881 to 2005 (relative to a reference period 1951-1975)
spatially-averaged over the 30-degree latitudinal belts of the globe (Lugina, et al., 2006).
- types of the atmospheric circulation patterns (zonal and meridional) (Catalogue..., 1964).
Figure 1. The location of the weather stations and tree-ring sites in the Russian Altai Mountains
Comparing to the Northern Hemisphere the tendency of air temperature increase in the second half
of the 20th century over the Altai Mountains has been observed generally earlier, since 1950s
(Figure 2). Maximum warming rate in the last quarter of the 20th century is typical to winter in the
Altai (0,85°C/10 years) as well as in the entire Northern Hemisphere. Minimum warming rate is
observed in autumn (0,17°C/10 years). At the turn of the XX-XXI centuries warming rates slow
down in the Altai region while the temperature level is still high. The analysis of climate change
spatial patterns showed that the most intense temperature increase during the last 20-30 years is
specific to the most arid part of the region - South-Eastern Altai.
Figure 2. Anomalies of the seasonal year temperature (w.r.t. 1940-2004)
(red line – 5-year running mean)
Correlation analysis between seasonal air temperature variability in the Altai and in the temperate
and polar latitudes and the whole Northern Hemisphere shows that there are periods of synchronous
and asynchronous temperature changes in the Altai region against the background of global climate
changes. Synchronous changes in the Altai and the entire Northern Hemisphere are observed in all
seasons only in 1975-2004 years, in the Altai and polar latitudes in spring and summer at the same
period. These regional climate changes are partly associated with the circulation epochs, especially
in winter. For example, winter temperature intensive increase stopped in the early 1990s along with
the beginning of new circulation epoch.
To extend the time series over the past 350-400 years, mean summer temperature and precipitation
were reconstructed applying dendroclimatological methods (Cook, 1985; Methods of
dendrochronology, 1990) and using the WSL Dendro data base (www.wsl.ch/dendro) including
tree-ring width and maximum tree-ring density and core samples received during the field
expeditions as well as the treeline position estimates. According to the dendrochronological
reconstruction mean summer temperature increased from the end of the Little Ice Age (LIA) to its
maximum in the 1990s by approximately 2°C, to the average for the period 1986-2004 years about
1.3°C (Figure 3). Recent fast warming especially from the mid-1980s in the Altai Mountains is nonexclusive. The similar abrupt increase of mean summer temperature was observed, for example, in
the second half of the 19th century.
Figure 3. Dendrochronological reconstruction of the mean summer temperature in the Altai
Mountains
Spectral analysis revealed the important role of natural cyclical recurrence in climate changes in the
region such as quasi-biennial cycle of the atmospheric circulation (2-4 years), solar activity cycle
(10-12 years), Brückner cycle (35-40 years) and 100-120 year cycle (century cycle of solar
activity+Brückner cycle)
Vertical hydrothermal gradients were employed to characterize each altitudinal belt in different
geobotanical provinces of the Altai Mountains (Central Altai, North-Eastern Altai, North-Western
Altai, North Altai and South-Eastern Altai) by the climatic area of distribution. Each belt is
characterized by the range of mean summer temperature and annual precipitation. Mean summer
temperature vertical gradients in the Altai Mountains are 0.5 – 0.6°С/100 m in the Central Altai,
0.6°С/100 m in the North Altai and 0.80-0.82°С/100 m South-Eastern Altai. Annual precipitation
vertical gradients range from 20-40 mm/100 m to 150-200 mm/100 m in the different localities of
the Altai Mountains.
As treeline against the other belt borders strongly limited by summer temperature (7.5-9°C) its
eventual dynamics since the end of the LIA over the Altai Mountains were estimated using the
altitudinal temperature gradients, weather station data and dendrochronological mean summer
temperature reconstruction. Theoretical evaluation shows that mean summer temperature increase
of 1.3°C from the end of the LIA (1860-1880 years) to the period of 1986-2004 year causes treeline
to rise maximum by 180-280 m in different localities of the Altai Mountains. Received estimations
on the whole are confirmed by the field data.
Bibliography
1. Catalogue of the macro-synoptic processes by the G.Ya. Vangengeim from 1891 year / Ed. M.S.
Bolotinskaya, L.Y.Ryzhakov. (1964). Leningrad, Rotaprint AARI, 159 p. (in Russian).
2. Cook E. R. (1985). A time series analysis approach to tree-ring standardization: Ph.D. thesis.
The University of Arizona, 171 p.
3. Lugina К.М., Groisman P.Ya., Vinnikov K.Ya., Koknaeva V.V., and Speranskaya N.A. (2006).
Monthly surface air temperature time series area-averaged over the 30-degree latitudinal belts of the
globe, 1881-2005. In Trends: A Compendium of Data on Global Change. Carbon Dioxide
Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak
Ridge,
Tenn.,
U.S.A.
doi:
10.3334/CDIAC/cli.003
http://cdiac.ornl.gov/trends/temp/lugina/lugina.html
4. Methods of dendrochronology: Applications in the Environmental Sciences / E.R. Cook, L.A.
Kairiukstis. (1990). Eds. Norwell, Mass.: Kluwer Acad., 394 p.
5. WSL Dendro Database, Switzerland / Swiss Federal Institute for Forest, Snow and Landscape
Research. URL: Http://www.wsl.ch/dendro/dendrodb.html.