The glaciers of the Tianshan Mountains are a major water source for northwestern China and other neighboring countries, such as Kyrgyzstan and Kazakhstan but rapid glacial retreat is occurring due to global warming. Among the glaciers in Tianshan Mountains, glacier No. 1 stands out because it is only 120 km from the regional capital of Urumqi; the closest glacier to an urban area in the world. Consequently, its rapid retreat in recent years has impacted nearby populations.
Glacial retreat in Tianshan Mountains
According to data over the past 45 years, the No. 1 glacier in the Tianshan mountains has, on average, reduced its thickness by 11 m, and for some parts of the glacier, the reduction is closer to 20 m. Based on an analysis of data between 1958 and 2003, there has been 18.38 million cubic meters of ice lost from the No. 1 glacier (Xinhuanet 2005).
In Kyrgyzstan, the loss of the Ak-shirak Range glaciers has accelerated for about one-fifth of their remaining volume during recent thirty years (Khromova, Dyurgerov and Barry 2003). In the northern areas of Tianshan mountains range, which Kyrgyzstan shares with China and Kazakhstan, studies show that the glaciers have been losing nearly 2 cubic km of ice per year between 1955 and 2000. This amount of ice can help supply water to this arid region. Kirby (2003) reported more than one percent of the total volume of these glaciers was lost every year since mid-1970s.
During the last century, the glaciers in Tajikistan lost 20 cubic km of ice. There has been a loss of about two percent of its total length of the Fedchenko Glacier during the last century. The Skogatch Glacier retreated nearly 10% of its volume during the past several decades (Novikov 2003).
Global warming is the primary cause of the thawing of the glaciers of Tianshan Mountains (Rai and Gurung 2005).
A decrease in surface albedo, through dust deposition on the adjacent snow-ice surfaces from mining activity, is a possible factor accelerating summer ablation in the vicinity of these glaciers.
In Northwest China, the water melt from the glaciers resulted in an increase of runoff of more than 5% during late 20th century (Yao et al. 2004).
The glacial retreat in the Tianshan Mountains will result in a short-term increase in snowmelt water, which drains into surrounded rivers and streams. A long-term decrease will follow if the current situation continues (Novikov 2003), which will bring drought to the northwest arid regions in China.
A decrease in surface albedo will accelerate global climate change, which will in turn increase the speed of glacial retreat.
Summer flooding along rivers in central China has been very intense in recent years. Approximately half a million people have had to leave their hometown within the Anhui, Henan and Jiangsu provinces.
Many problems with retreating glaciers still need to be addressed, such as the assessment of hazards, evaluation of effects on sea level rise, and climate change.These need to be better understood in order to implement quantitative research and disaster mitigation (Rai and Gurung 2005).
Khromova, T. E., M. B. Dyurgerov and R. G. Barry. 2003. Late-twentieth century changes in glacier extent in the Ak-shirak Range, Central Asia, determined from historical data and ASTER imagery. Geophys. Res. Lett., 30, 1863-1867.
Kirby, A. 2003. Kazakhstan's glaciers 'melting fast'. BBC News September 4, 2003http://news.bbc.co.uk/2/hi/science/nature/3077422.stm (last accessed 17 November 2009
Novikov, V. 2003. Tajikistan 2002, State of the Environment Report. In Climate Change. Research Laboratory for Nature Protection. http://enrin.grida.no/htmls/tadjik/soe2001/eng/htmls/climate/state.htm
Rai, S. C. and C. P. Gurung. 2005. An Overview of Glaciers, Glacier Retreat and Subsequent Impacts in Nepal, India and China. WWF Program. http://assets.panda.org/downloads/himalayaglaciersreport2005.pdf (last accessed 17 November 2009)
Xinhuanet. 2005. Tianshan's glacier thawing faster. ed. Xinhuanet. Urumqi: Xinhua News. http://news.xinhuanet.com/english/2005-12/29/content_3985419.htm (last accessed 17 November 2009)
Yao, T., Y. Wang, S. Liu, J. Pu, Y. Shen and A. Lu. 2004. Recent glacial retreat in High Asia in China and its impact on water resource in Northwest China. Science in China Series D: Earth Sciences, 47, 1065-1075