Written by Ann Piersall, 2008

OVERVIEW Stretching over 1800 km east to west the Tien Shan mountain range extens from the Xinjiang province of Western China across southern Kazakhstan and the entire country of Kyrgyzstan to the border of Uzbekistan. North-south the Tien Shan are as wide as 500 km in some locations. The Tien Shan separate the Junggar (Dzungarian) Basin to the north and the Taklimakan Basin in the south. Their geographic location is between 40°N and 45°N and 67°E and 95°E. The Tien Shan cover approximately 100,000 square kilometers (Rowan, 2002). , 2008

In Chinese, Tien Shan means “Celestial mountains” or “Mountains of Heaven”. This name is in reference to the appearance the mountains often take from the distance of appearing to float in the heavens above the dust of the surrounding deserts (Graetz 2008, Rowan 2002).

The Tien Shan are part of the Himalayan orogenic belt which was formed by the collision of the Indian and Eurasian plates in the Cenozoic era. The eastern Tien Shan is mostly crystalline and sedimentary rock dating back to 540 million years ago. The western Tien Shan is younger softer rock formed under heat and pressure about 245 million years ago (Rowan, 2002).

A majority of the Tien Shan sits within the political boundaries of the country of Kyrgyzstan. Approximately 94% of Kyrgyzstan is mountainous, with half of the country above 3000 meters. The stark and rugged landscape makes livelihood very difficult. Many different ethnic groups call the Tien Shan home. The largest ethnic group are the Kyrgyz. The Kyrgyz are a group that originated from a mix of tribes including Mongols and a tribe that migrated from the Siberian Yenisei River. Uzbeks, Uighur, Kazaks and Dungan (Muslim Chinese) are other ethnic groups that live with in the Tien Shan. Starting in the mid 1800’s a strong Russian presence developed into 150 years of Soviet rule over the area. During this time the nomadic ways of most ethnic groups were suppressed. Soviet Rule ended in the Tien Shan in 1991 with the collapse of the USSR and the Central Asian republics declaring independence. Today, a large Russian population along with some Ukrainians and Tajik refugees are found among the many ethnic groups in the Tien Shan. Many mountain people of the Tien Shan are now once again semi-nomadic pastoralists, often spending their winters in small villages (Rowan, 2002). Despite independence, the countries and peoples of the Tien Shan are struggling politically, economically and culturally.

The extensive mountains of the Tien Shan can be geographically organized in many different fashions. Generally, references are made of five main orographic areas. It is important to note that the Tien Shan hold a total of 88 constituents chains with fourteen peaks towering over 6000m. The five main areas of the Tien Shan with their most prominent ranges are: the Central Tien Shan (Kakshal-Too, Sary Djaz, Koolyu-Too), Norther Tien Shan (Kyrgyzskii, Talasskii, Kungei Ala-Too), Internal Tien Shan (Susamyr-Too, Naryn-Too, At-Bashy), Western Tien Shan (Ferganskii, Chatkalskii) and South Tien Shan (Alaiskii, Turkestanskii) (Azykova, 2002).

The ranges of the Tien Shan culminate at the Central Tien Shan, which the locals refer to as Muztag meaning “Ice Mountain”. Within the Central Tien Shan is Kokshal-Tau which contains the highest mountains of the Tien Shan and the most extensive network of glaciers.

The Inylchek Glacier is the largest glacier and centerpiece of the Central Tien Shan. Extending 62 km in length with a width of over 3 km, the Inylchek Glacier is the third longest glacier outside the polar regions. It is estimated that the glacier holds enough ice to cover the entire country of Kyrgyzstan in three meters of melt water (Stewart, 2002). The first outside to travel into the area and visit the glacier was the European Piotr Semnov in 1857. Climbing in the area began in the early 1900’s and continued through the 1930’s. Under Soviet rule, the permitting system restricted foreign access. It was not until after the collapse of the Soviet Union in 1991 that foreign climbers began to climb in the area (Stewart, 2002).

The two tallest peaks in the Tien Shan, Jengish Chokosu and Khan Tengri, are both located in the Central Tien Shan. Situated on the border of China and Kyrgyzstan Jengish Chokosu (7,439m), also called Peak Pobeda or Victory Peak, is the highest summit in the Tien Shan. A sprawling and bulky mountain; it is also the northern most true 7000m peak in the world. It was first climbed by Soviet climbers in 1938 (Stewart, 2002).

Located just north, on the border of Kazakstan, is the towering pyramid of Khan Tengri (6,995m). Khan Tengri means the “Prince of Spirits” or “Lord of the sky” in Uighur. The Kazakh name for the mountain is Kan Tan meaning “Blood Mountain” referring to the brilliant sunsets that fall upon the peak at night (Stewart, 2002). With its ice cap Khan Tengri rises above 7000m, making it the northern most 7000m peak in the world. The aesthetic beauty of the peak has been noted since it was first summited in 1931 by Mikhail Pogrebetsky. (Stewart, 2002). Currently it is featured on the Kyrgyz 100 som note. Recently in 2004, 11 mountaineers were killed from an ice avalanche on Khan Tengri (Gripped World News, 2004).

The Tien Shan are characterized by a dry continental climate with strong seasonal variations that marks most of Central Asia. Temperatures vary strongly according to altitude. Most areas receive strong solar insolation all year with little annual precipitation or cloud cover. However, weather in the mountains in continuously changing and violent storms often enclose the Tien Shan for weeks.

Meteorological data indicates that the western and northern peripheries of the Tien Shan have a more mild and temperate climate than the inner regions (Solomina et al., 2004). The northern Tien Shan generally receive more precipitation as they are the first mountains intercepted by winter storms crossing the plains of eastern Europe and Central Asia. The presence of the Tien Shan contributes to the arid nature of Central Asia including the Taklamakan and Tibetan Plateau (Koppes et al., 2008).

Over 30,000 rivers and streams mostly originating from glaciers and over 2,000 lakes are spread across the Tien Shan. The largest lake is Yssyk-Kul located in the eastern regions of the Tien Shan. The most prominent river is the Naryn river which flows east to west to join the Kara Darya in the Fernaga Valley of Kyrgyzstan forming the Syr Darya (Azykov, 2002). Glacial melt water make up the majority of the water in the region, which is why the mountains as aptly referred to as the water towers of Central Asia.

The Tien Shan hold thousands of glacier ranging from sprawling dendritic valley glaciers such as the Inylchek Glacier to numerous small hanging glaciers. In discussing glaciation, a basic understanding of glacier dynamics is crucial. Glaciers are dynamic, moving masses of ice formed by layers of compacted snow that deform and flow in response to gravity and pressure. A common term used in describing glacier is mass balance, the difference between accumulation and ablation. Accumulation on a glacier occurs at higher elevations through snowfall, wind deposition, rain, frost, hail and avalanches. Ablation generally takes place in warmer season on the lower elevations from ice melt, wind, calving and sublimation. The line on the glacier that marks where the ablation zone turns to accumulations is called the equilibrium line altitude (ELA). The very bottom of the glacier is referred to as the terminus. (Harper, 2007)
Glaciers move through two processes; ice deformation and basal sliding. Basal sliding can be defined as the entire mass of ice sliding on the bed surface. Deformation occurs as glide on a basal plane, grain boundary slip and recrystalization. Glacial flow originates at the top of the glacier with submergent flow. Here annual layers of snow are deposited and begin an intrusive flow that continues in the middle of the glacier where the flow is typically rectilinear. Below the ELA the flow transitions to emergent flow. Variations in topography and the bed surface can cause changes in an individual glacier’s flow (Harper, 2007).

The mass balance of a glacier is continuously responding to climatic changes, however due to the mechanics a time delay exists in the response. It often take decades for a climatic event to become very apparent (lag time) and often centuries for the evidence of the event to disappear (memory time) (Harper, 2007).

It is also very important to understand the different types of measurements used to quantify glaciers and changes in glaciation. Measurements can be divided into two main categories: direct and indirect. Direct measurements offer the most accurate information; however they are spatially limiting, time consuming and expensive. Direct measurements of mass balance require measuring both the accumulation and ablation of a glacier. Accumulation or input can be measured by digging snowpits and measuring annual layers of accumulation or by probing. Ablation or output can be measured through ablation stakes that must be monitored to determine melt. Direct measurements of area require extensive time with GPS to accurate map the margins of the glacier to determine area (Harper, 2007).

Due to the limiting factors of direct measurements, indirect measurements are typically used. Many different methods exists including; remote sensing, hydrological methods, climatic methods, lichenometry and ground truth data (Harper, 2007).

Remote sensing, the use of satellite and aerial photographs can be used to determine the area of glaciers. If historic images are available, changes in glacial area and terminus elevation can be determined from comparing past to present images. Often historic images are difficult to find due to the remote locations of many glacier and the relatively recent advent of satellites.

The hydrological method estimates mass balance by equating the amount of precipitation in an area against the runoff and predicted evaporation to estimate accumulation and ablation. This requires some type of measurement of stream runoff and the presence of meteorological stations to determine input making it very difficult for remote locations. Similarly, using climate data requires meteorological stations. Two different methods in determining mass balance can be used with climate data. First the degree day method calculates melt by measuring the amount of time the temperature was high enough for melting to occur. Second, energy balances can calculated by measuring the albedo (shortwave radiation), the longwave radiation, the sensible heat the latent heat and the precipitation to estimate heat.

Lichenometry is identifying the age of lichens present on rocks below the terminus of a glacier to estimate when that location was last covered with ice. Similarly, remnant moraines can often be aged to estimate the greatest extent of the glacier and when it occurred (Harper, 2007).
Currently the accepted estimate of total glaciated area of the Tien is between 6,000 and 8000 square kilometers (Aizen et. al, Bolch 2006, IRIN 2008, Solomina et al. 2004, Stewart 2002). The Inner part of the Tien Shan have over 3700 glaciers covering 3400 square km. Historically, the Tien Shan have been heavily glaciated. Remnant moraines provide evidence for extensive and repeated glaciation during the late Pleistocene (Koppes et al, 2008).

The earliest historical descriptions of glaciers in the Tien Shan date to the late 19th century from exploration by Semenov in 1858, Kassin in 1915 and Korzhenevsky in 1930 (Solomina et al., 2004). Although earlier travelers did not penetrate the Tien Shan travelers on the Silk Road often made notes of the snow and ice of the Tien Shan such as Xuan Zang, the seventh century Chinese traveler-monk, who wrote of the Tien Shan: These mountains stretch for thousands of leagues: among them are several hundred tall peaks which reach to the very sky; the valleys are dark and full of precipices. The snow that has accumulated here since the creation of the world has changed into ice rocks that do not melt either in spring or summer. There is a strong cold wind and travelers are molested by dragons.

Due to the limited access to the area during Soviet rule research and current primary literature on glaciation in the Tien Shan in limited. Little research has involved direct measurements. This coupled with the large number of glaciers and remoteness of the area has only allowed recent studies to focus on small specific regions within the Tien Shan. A majority of glaciers in the Tien Shan are unnamed and many potentially unvisited. Information of glaciers and glacier retreat for the entire Tien Shan are generalizations based off of scientific extrapolations from smaller studies and regional patterns. Specific quantitative information cannot be applied to all glaciers.
Equilibrium line altitudes of glacier is the Tien Shan varies from 3500-3600 meters on the Western Tien Shan to 4440 meters in the Central Tien Shan. (Solomina et al., 2004). The lowest ELAs are found on the northern ridges of the Tien Shan as they receive the most precipitation from winter storms. Traveling south the ELAs rise rapidly (Koppes et al., 2008).

Historically glaciers in the Tien Shan have appeared to respond primarily to changes in precipitation rather than small regional variations in temperature. However recent increases in temperature are strongly tied to glacial retreat (Bolch 2007, Koppes et al., 2008, Solomina et al. 2004).

The areas of glacial ice coverage with the Tien Shan are decreasing in similar fashion to other parts of the world (Aizen et al. 1997, Bolch 2004, Bolch 2007, Cao 1998, Khromova et al. 2003, Solomina et al. 2004). Evidence from lichenometry suggests that retreat began at the end of Little Ice Age (Solomina et al., 2004). Although glacier retreat is not homogeneous a decrease in glacier extent of over 30% is the consensus for the Tien Shan (Aizen et al. 1997, Bolch 2004, Bolch and Marchenko 2006, Bolch 2007, Cao 1998, Khromova et al. 2003, Niederer et. al. 2008, Solomina et al. 2004). The magnitude of the decrease for each individual glacier depends strongly on the size, location and weather regime at the glaciers’ location (Bolch, 2007).

Research indicates that glacial retreat started at the end of the Little Ice Age, approximately 150 years ago (Aizen, 2005). The estimated linear retreat from the end of the 19th century to the 10th century was in most cases less than 100 meters (Solomina et al., 2004). In the northern Tien Shan a more pronounced disintegration has been noted of glaciers since 1979 (Vilesov and Uvarov, 2001). This apparent acceleration in glacial retreat in the past several decades appears to be true for a majority of glacier in the Tien Shan.

One of the most extensive studies in the Tien Shan included 293 glaciers and using aerial photographs and lichenometry determined that even in the most general terms glacier retreat was occurring both in linear distance and retreat in terminus elevation. Average linear distance retreat was calculated to be a retreat of 989 ± 540 meters from the glacier terminus to Little Ice Age (LIA) moraine over the past 150 years. The average difference in elevation of the terminus and the LIA moraine was 151 ± 105 meters (Solomina et al., 2004).

Although research is limited in scope, similar patterns have been found in all studies. Given the limitations the magnitude of glacial retreat can only be estimated, but there is clear evidence that glacial recession is occurring. It appears that retreat both in linear distance and frontal elevation rise is most prominent in the Northern Tien Shan. The effects of glacial retreat also appear to greatest for large compound-valley (Solomina et al., 2004). There most significant trends associated with glacial retreat is a strong correlation with increased temperatures (Bolch 2007, Koppes et al., 2008, Solomina et al. 2004). It is important to remember that little ground truth data exists for a majority of research in the Tien Shan making additional studies warranted. Future research would quantify the amount and rate of glacial change.

Evidence over the past 30 years permafrost has been warming in the Tien Shan. (Bolch and Marchenko, 2006). Modeling indicates a retreat of the lower altitudinal boundary of permafrost retreating upward by 150 meters since the end of the Little Ice Age. Additionally, it is estimated that the area of permafrost distribution has decreased by 16% (Marchenko et al., 2007).

Glaciers are a key indicator of climate change as they react sensitively to climate. Research indicates that glaciers in the Tien Shan are receding in extent, volume and elevation. With current conditions it can be assumed that glaciers will continue to retreat in the Tien Shan creating and intensifying many environmental, social and political problems.

Most importantly, the high mountains of central Asia serve the crucial function as the primary water supply and water storage for over 100 million people Reductions in glacial extent and increased melt will inevitably change river runoff regimes. Although initially the volume of discharged water could increase, the overall stability of the water supply will be reduced as glacial extent is reduced. The large reduction of glacier area in the Tien Shan has many downstream implications for food production, energy development, the articulation of water policies and regional security (IRIN, 2008).

Increases in air temperatures and the melting of glaciers will also impact lowland desertification and glacier outburst floods (Aizen et. al., 2007). It is predicted that slope instability will increase, increasing the probability of landslides, thermokarst and mudflows (Bolch and Marchenko, 2006).

Local, regional and international research is warranted in light of the limited scope of data available on the Tien Shan. Future studies will provide a key incremental links to more complete future assessments of the impacts of glacial recession in the Tien Shan as glacial retreat intensifies with anthropogenic warming. Additionally, empirical assessments linking the social and physical processes of glacial recession and climate change in the Tien Shan will promote dialogs to promote additional research and development of solutions to global climate change.


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