The Variation Of Glacier And Its Response To Climate Change In The Tanggula Mountains (Tibet Plateau) From 1990 To 2015

The Tanggula Mountains are located in a transition zone between wet and dry climate of the Tibet Plateau,the spatial distribution of climate and gradient changed signif icantly in the past decades.Most of the glaciers in this region are continental glaciers,however,some temperate-type glacier are distributed in the southeastern of the study area,which is influenced by subtropical oceanic monsoons.The study about glacier has a great signif icance to reveal the characteristics and relationship between glacier retreat and climate change,thus,a detailed investigation of recent glacier variations in the Tanggula Range is essential.In this paper,we extracted glacier outlines in 1990,2000,2007 and 2015 with the help of the Chinese Glac ier Inventory data and Landsat data(TM,ETM+ and OLI)using a comprehensive method,which was improved from the ratio threshold.In addition,the method was evaluated based on GPS survey and field survey conducted in the Tibet Plateau.The experiential work with visual interpretation was also used to modify the glacier boundary.We compared and analyzed the glacier changes in different periods and different area of the Tanggula Mountains,particularly for continental and temperate-type glaciers.We discussed the variation of glacier and its response to climate change.Therefore,the main conclusions of the study are as follows:(1)The glacier area of the Tanggula Mountains was 2062.19 km2 in 1990,and reduced to about 336.72 km2(16.33%)in the last 25 years.The glacial retreat was much faster in the 21 st century than that of the 20 th century and the rates of glac ier decline was the slowest,fastest,and faster in 1990-2000,2000-2007,and 2007-2015,respectively.(2)The temperature of study area increased prominently,while the precipitation changed weakly.The rise of temperature was likely the main reason for the rapid decrease of glacier.(3)The temperate-type glacier is mainly located in the eastern part of the Tanggula Mountains,and covers a small area.However,its glacier retreat was significantly faster than the continental glac ier in past 25 years,because the temperate-type glaciers are more sensitive to climate change,and has close relationship with the conditions of glacier formation.In addition,the temperate-type glacier are distributed in the lower altitudes and covers very small area.Thus,the temperate-type glacier was more sensitive to the effect of temperature heating and retreated faster than the continental glacier.