Glacier extent changes and possible causes in the Hala Lake Basin of Qinghai-Tibet Plateau

Glacier is a common sensitivity indicator of environmental and global climate change.Examining the relationship between glacier area and climate change will help reveal glacier change mechanisms and future trends.Glacier changes are also of great significance to the regulation of regional water resources.This study selected the Hala Lake Basin in the northeastern Qinhai-Tibet Plateau as a study area,and examined the relationships between the temporal and spatial change of glaciers in the northeastern Qinghai-Tibet Plateau and climate change based on remote sensing imagery,climatological data,and topographic data during the past 30 years.Results showed that glacier area in the Hala Lake basin fluctuated and decreased from106.24 km2 in 1986 to 78.84 km2 in 2015,with a decreasing rate of 0.94 km2·yr-1.The number of glacier patches,mean patch area,and largest patch index all decreased from 1986 to 2015,while the splitting index increased from 1986 to 2015,indicating that the landscape fragmentation of glacier in the Hala Lake Basin was increasing significantly during the study period.Glacier area change was mainly concentrated in the slopes>25°with an altitude of 4500-5000 m,and the retreating rate of glacier of sunny slope was obviously higher than that of shady slope.Geometric center of glacier in the basin moved from southwest to northeast towards high altitude.Results of the response of glacier extent to climate change showed that temperature was the dominant factor affecting glacier area dynamic change in the Hala Lake Basin.It is predicted that in future several years,the glacier area will decrease and fragment continually as a result of global warming on the Tibetan Plateau.

Movement and variation of four typical glaciers in the Qilian Mountains,northwestern China

We selected four typical glaciers in the Qilian Mountains and investigated their movements and variation using advanced technologies such as remote sensing, photographic measurements, and global positioning systems. The velocity of glacier movements in the Qilian Mountains is relatively low, and there has been no significant variation during the past 50 years. Glacier motion has maintained a normal style. The movement velocity of Laohugou Glacier No. 12 presented a decreasing trend （by 48%） from 1960 to 2012. The movement velocity of the Qiyi Glacier also presented a decreasing trend （by 48.1%） from 1958 to 2012; it decreased by 29.4% from 1958 to 1977 and by 26.5% from 1977 to 2012. Therefore, the Qiyi Glacier＇s movement velocity varied greatly over the earlier 20 years （1958 1977）, but presented a small decreasing trend during the latter 30 years （1977-2012）. By comparing the movement velocity variation of these typical glaciers, we determined that the extent of variation was consistent among large glaciers （such as Laohugou Glacier No. 12） and small glaciers （such as the Qiyi Glacier and Yanglonghe Glacier No. 5）, despite their different sizes.

Significance of glacio-morphological factors in glacier retreat：a case study of part of Chenab basin,Himalaya

A study has been carried out in part of Chenab basin,Himalaya to understand the relationship between glacio-morphological factors and change in glacial area. Initially change in areal extent of glaciers was derived for two time frames(1962-2001/02 and 2001/02-2010/11). The study comprised of 324 glaciers for the monitoring period of 1962-2001/02 for,which 11% loss in glacial area was observed. Two hundred and thirty-eight glaciers were further monitored between 2001/02 and 2010/11. These glaciers showed an area loss of 1.1%. The annual deglaciation has been found to be higher during the period of 1962-2001/02 compared to 2001/02-2010/11. The spatial and temporal variability in deglaciation was also addressed usingglacio-morphic parameters. Area,length,percentage of debris cover,and various elevation parameters of glaciers were observed to have significant controls on relationships to the rate of glacial shrinkage. Largerarea and longer glaciers show a lower percentage of retreat than smaller and shorter ones. Moreover,glaciers located at lower altitudes and having gentle slopes show more area retreat. The results of area retreat in debris covered and debris free glaciers supports that the glaciers covered by debris retard ice melting at some extent. 158 glaciers were observed having no debris cover,and these exhibit 14% of loss in surface area. In glaciers having 40% debris cover,8% of deglaciation was observed. The glaciers located below equilibrium line altitude(ELA) have experienced 4.6% of deglaciation for the time frame 2001/02 – 2010/11 whereas it was found to be 1.1% for the glaciers occurring above ELA. However,theorientation of glaciers did not show any considerable influence on glacial change based on hypothesis.

东亚沿海山地末次冰期冰川与环境

对东亚沿海山地末次冰期冰川发育的气候条件、构造背景、冰进时序、发育规模等研究表明，台湾山地保存着3期冰川作用遗迹，冰川的最大前进规模发生在MIS3b阶段．其规模大于MIS2阶段：日本山地冰期系列齐全，包含了末次冰期的早（MIS4）、中（MIS3）、晚（MIS2）3个阶段的冰进．其规模是MIS4／3阶段大于MIS2阶段：而长白山存在2期冰川作用的遗迹，即末次冰盛期（MIS2）和晚冰期。在相似的冬雨（雪）型季风影响区，冰川发育的时序与规模也有一定不同．反映出在大气候背景下的区域性差异，在东亚季风影响范围内．末次冰期的环流变化在各地也很不一致。最新推算的现代理论雪线自北（日本）向南（台湾）依次递增．范围是2750---4245m．除日本北部的高纬地区雪线降低值400m之外．末次冰盛期（LGM）的雪线降低值在800～1300m之间．平均值1000m左右。东亚沿海山地冰川发育与新构造运动密切相关．更新世山体的快速抬升为冰川发育的内因．如台湾山地在末次冰期的MIS3b阶段．山体的抬升量约为250ml．对山体的高度和雪线变化有很大影响。

滇西北山地末次冰期冰川发育及其基本特征

对滇西北海拔4000～4500m山地的第四纪冰川发育和平衡线高度进行了研究．结果表明：古冰川发育主要依托海拔4000～4300m的夷平面，早中期发育小型的冰帽以及流入四周谷地的山谷冰川，晚期主要发育规模较小的冰斗冰川．冰川主要发育期为末次冰期，古冰川平衡线、山体最高峰以及夷平面的高度显示，冰川发育所依托的夷平面在末次冰期时超过古平衡线，二者差值为50～400m，为冰川发生提供了良好的地形与地势条件．冰川规模演化表明，滇西北地区多处山地MIS3中期的冰川规模大于末次冰盛期（LGM），可能与MIS3中期较强南亚季风带来较丰富的降水有关．古气候研究资料以及研究区的冰期系列表明，滇西北海拔4000—4500m山地末次冰期的冰川作用是构造和气候相耦合的结果．

1988-2013年布加岗日地区冰川变化及其对气候变化的响应

基于Landsat TM/ETM+/OLI遥感影像,采用比值阈值和目视解译相结合的方法提取分析了唐古拉山东段布加岗日地区近25a来冰川现状及其变化,对比研究了四个时段的冰川变化特征及其对气候变化的响应。结果表明:1988—2013年研究区冰川退缩比较严重,面积退缩34.25km2,占1988年冰川面积的18.67%,且不同时段冰川退缩速率不同,1988—1994—1999—2006—2013年冰川退缩表现为:慢—最快—中等—快的特点,冰储量预测减少15.38%。夏季气温升高很可能是造成冰川加速退缩的主因,冰川变化对气候变化的响应更好地体现在长时段的气候变化上,而短时段气候变化对冰川总体变化趋势有一定的作用,这是造成各个时段冰川变化差异性的原因。研究区北坡冰川退缩明显快于南坡,这种变化的差异性一方面可能是由研究区季风气候特征和水汽来源对不同朝向冰川的影响造成的,另一方面也受冰川发育规模、分布海拔的影响。

Late Glacial glacier-climate modeling in two valleys on the eastern slope of Samdainkangsang Peak, Nyaiqentanggulha Mountains

Well-preserved Late Glacial moraines in the Barenduo and Yuqiongqu valleys on the eastern slope of the Samdainkangsang Peak present an opportunity to reconstruct glacier extents and examine the character of the climate during the Late Glacial stage in the Nyaiqentanggulha Mountains. This study employs a coupled mass-balance and ice-flow model to reconstruct the glacier extents in the two valleys and assess the magnitudes of temperature and precipitation change during the Late Glacial period. Model results indicate that during the Late Glacial, the Barenduo valley contained an ice volume of 1.67x 108 m3, with the equilibrium-line altitude （ELA） being -5500 m asl; and the Yuqiongqu valley had an ice volume of 5.56x 108 m3, with the ELA being -5470 m asl. A climate scenario, temperature depression of 2.6-2.8°C and 60-70%, percent of modern （1981-2010） precipitation, can sustain both of the Late Glacial glacier extents in the two valleys. A 50% increase or decrease from modern precipitation would have been coupled with the respective Late Glacial temperature depressions of 1.6 and 3.0°C in the Barenduo valley, and 2.1 and 2.8°C in the Yuqiongqu valley.