Spatial variability of glacial changes and their effects on water resources in the Chinese Tianshan Mountains during the last five decades

Changes in glaciers in the Chinese Tianshan Mountains have been analyzed previously. However, most previous studies focused on individual glaciers and/or decentralized glacial basins. Moreover, a majority of these studies were published only in Chinese, which limited their usefulness at the international level. With this in mind, the authors reviewed the previous studies to create an overview of glacial changes in the Chinese Tianshan Mountains over the last five decades and discussed the effects of glacial changes on water resources. In response to climate change, glaciers in the Tianshan Mountains are shrinking rapidly and are ca. 20% smaller on average in the past five decades. Overall, the area reduction of glacial basins in the central part of the Chinese Tianshan Mountains is larger than that in the eastern and western parts. The spatial differentiation in glacial changes are caused by both differences in regional climate and in glacial factors. The effects of glacial changes on water resources vary in different river basins due to the differences in glacier distribution, characteristics of glacial change and proportion of the glacier meltwater in river runoff.

Glacial change in the vicinity of Mt. Qomolangma （Everest）, central high Himalayas since 1976

Glaciers are one of the most important land covers in alpine regions and especially sensitive to global climate change. Remote sensing has proved to be the best method of investigating the extent of glacial variations in remote mountainous areas. Using Landsat thematic mapping （TM） and multi-spectral-scanner （MSS） images from Mt. Qomolangma （Everest） National Nature Preserve （QNNP）, central high Himalayas for 1976, 1988 and 2006 we derived glacial extent for these three periods. A combination of object-oriented image interpretation methods, expert knowledge rules and field surveys were employed. Results showed that （1） the glacial area in 2006 was 2710.17 ＋ 0.011 km2 （about 7.41% of the whole study area）, and located mainly to the south and between 4700 m to 6800 m above sea level; （2） from 1976 to 2006, glaciers reduced by 501.91± 0.035 km2 and glacial lakes expanded by 36.88 ＋ 0.035 kin2; the rate of glacier retreat was higher in sub-basins on the southern slopes （16.79%） of the Himalayas than on the northern slopes （14.40%）; most glaciers retreated, and mainly occurred at an elevation of 4700-6400 m, and the estimated upper limit of the retreat zone is between 6600 m and 6700 m; （3） increase in temperature and decrease in precipitation over the study period are the key factors driving retreat.

Climate， mass balance and glacial changes on small dome of Collins Ice Cap， King George Island， Antarctica

During 1991/1992 Chinese Antarctic Expedition, a full-year glacial investigations on the small dome of Coffins Ice Cap were carried out, the data from investigations showed that vertical temperature gradients on small dome were about 0. 79℃/100m and 0. 66℃/100m in the summer and in the winter separately. LOwer summer temperature in this area is one Of most important conditions for glacial development. In 1991/1992 the small dome was a weak positive balance year with a mass balance difference of 163 mm, annual ELA was 140m, mass balance gradient was 8.4mm/m and mass balance level was 928mm. Mass balance fluctuations on small dome in 1971-1992 were calculated by a new method, the results revealed that the small dome of Coffins Ice Cap was relatively stable over 21 years.

Quantifying glacial elevation changes in the central Qilian Mountains during the early 21^(st) century

Glaciers in the central Qilian Mountains provide important water resources for the arid Hexi corridor and Qaidam Basin;however,changes in these glaciers interact with climate change.Twenty-four bi-static image pairs of TerraSAR-X add-on for Digital Elevation Measurement(TanDEM-X)data,in addition to a Shuttle Radar Topography Mission-C/X band digital elevation model,and the technology of iterative differential synthetic aperture radar interferometry were used to carry out glacier elevation change analysis in the central Qilian Mountains in China during 2000–2014.Glacier elevation changed with an average rate of(−0.47±0.06)m yr^(−1),while changes in elevation of(−0.51±0.06)m yr^(−1) and(−0.44±0.06)m yr^(−1) were found in the northern(including the Zoulangnan,Tuolai,and Tuolainan mountains)and southern(including the Shulenan and Hark mountains)regions,respectively.Summer mean temperature has risen by 0.51℃(10 yr)^(−1)in the northern region and 0.48℃(10 yr)^(−1) in the southern region during 1989–2014;however,the change in amplitude of annual precipitation was 2.69 mm yr^(−1) in the northern region and 4.77 mm yr^(−1) in the southern region for the same period.These changes can be ascribed as major driving factors for the differences in the changes in glacial elevation in the northern and southern regions.Four types of glaciers existed in the region when considering the change in elevation of the glacial tongue and variation in the position of the glacial terminus:surging,advancing,intensively retreating,and slightly retreating glaciers.If elevation decreased more than 20 m on the part of glacier tongue,the glacier terminus position had commonly retreated more than 100 m.

Changes of Monsoonal Temperate Glaciers in China during the Past Several Decades under the Background of Global Warming

Based on various data,it can be concluded that eight monsoonal temperate glaciers in China were in stationary or ad-vancing between 1900s;930s and 1960s;980s,and were in retreating during 1930s;960s and 1980s;resent under the background of climate warming.The total glacier area has reduced by 3.11 km2 with a mean front altitude rise of 3.2 m/yr and 4 glaciers have disappeared in Mt.Yulong during 1957;999.Mass balance records indicated that glaciers had suf-fered a constant mass loss of snow and ice during the last several decades,and the accumulated mass balance in Hailuogou basin in Mt.Gongga was 10.83 m water equivalent in the past 45 years with a annual mean value of-0.24 m,and the value at Baishui glacier No.1 was-11.38 m water equivalent in the past 52 years with-0.22 m/yr.The inverse variation between mass balance and temperature in China and the Northern Hemisphere reflected that climate warming is mainly corresponding to constant ice and snow mass loss in the past 50 years.The change of the glaciers’ surface mor-phology has occurred since the 1980s,such as enlargement of glacier-lake and ice falls,resulted from the accelrative cli-mate warming.

Glacial Lakes in the Andes under a Changing Climate:A Review

In this article, we review the current knowledge of the glacial recession and related glacial lake development in the Andes of South America. Since the mid-1980 s, hundreds of glacial lakes either expanded or formed, and predictions show that additional hundreds of lakes will form throughout the 21 st century. However, studies on glacial lakes in the Andes are still relatively rare. Many glacial lakes pose a potential hazard to local communities, but glacial lake outburst floods(GLOFs) are understudied. We provide an overview on hazards from glacial lakes such as GLOFs and water pollution, and their monitoring approaches. In real-time monitoring, the use of unmanned aerial systems(UASs) and early warning systems(EWSs) is still extremely rare in the Andes, but increasingly authorities plan to install mitigation systems to reduce glacial lake risk and protect local communities. In support, we propose an international remote sensing-based observation initiative following the model of, for example, the Global Land Ice Measurements from Space(GLIMS) one, with the headquarters in one of the Andean nations.