Changes in glacial lakes and glaciers of post-1986 in the Poiqu River basin, Nyalam, Xizang (Tibet)   总被引：16，自引：0，他引：16  

Xiao-qing Chen  Peng Cui  Yong Li  Zhong Yang  Yong-qing Qi 《Geomorphology》2007,88(3-4):298-311

Glacial lakes and glaciers are sensitive indicators of recent climate change. In the Poiqu River basin of southern Tibet, 60–100 km NW of Mt. Everest, Landsat imagery defines post-1986 changes in the size and distribution of both glacial lakes and glaciers. Total area of glaciers in the 229-km² drainage area has decreased by 20%. The number of glacial lakes with areas in excess of 0.020 km² has increased by 11%, and the total area of glacial lakes has increased by 47%. The areas of typical large glacial lakes of the area (Galongco, Gangxico, and Cirenmaco) have increased by 104, 118, and 156%, respectively, and these increases are confirmed by field investigations.Comparing the 1986 data, the area of glaciers in the basin headwaters has decreased by 46.18 km² to a present total area of 183.12 km², an annual rate of change of 3.30 km²/year. Trends indicate that the total area of glaciers will continue to decrease and that both the numbers and areas of glacial lakes will continue to increase. Accompanying these trends will be an increased risk of debris flows, formed by entrainment of sediment in glacial-outburst floods and in surges from both failure and avalanche- and landslide-induced overtopping of moraine dams. Based on both the local and world-wide history of catastrophes from flows of these origins, disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible.  相似文献   

An Inconvenient Truth: blurring the lines between science and science fiction     

Roy W. Spencer 《GeoJournal》2007,70(1):11-14

Al Gore’s movie An Inconvenient Truth gives a variety of unusually biased interpretations of the state of climate science and global warming theory. These cover a wide range of natural events and processes which could potentially be impacted by global warming, but which the movie misrepresents as clear examples of the human influence on climate. A few examples include the mixing up of cause and effect in his graphical portrayal of temperature and carbon dioxide variations over hundreds of thousands of years; the repeated depiction of ice calving from glaciers as a sign of global warming; the implication that Hurricane Katrina was the fault of humans; and the particularly extreme view that the Greenland ice sheet will melt, flooding coastal cities worldwide. Ultimately, all of these are related to the widespread perception that scientists have uniquely tied global warming to anthropogenic greenhouse gas emissions. The real inconvenient truth is that science has no idea how much of recent warming is natural versus the result of human activities.  相似文献   

Pleistocene ice and paleo-strain rates at Taylor Glacier, Antarctica     

S.M. Aciego  J.L. Kavanaugh 《Quaternary Research》2007,68(3):303-313

Ice exposed in ablation zones of ice sheets can be a valuable source of samples for paleoclimate studies and information about long-term ice dynamics. We report a 28-km long stable isotope sampling transect along a flowline on lower Taylor Glacier, Antarctica, and show that ice from the last glacial period is exposed here over tens of kilometers. Gas isotope analyses on a small number of samples confirm our age hypothesis. These chronostratigraphic data contain information about past ice dynamics and in particular should be sensitive to the longitudinal strain rate on the north flank of Taylor Dome, averaged over millennia. The imprint of climatic changes on ice dynamics may be discernible in these data.  相似文献   

珠穆朗玛峰北坡局地环流日变化的观测研究   总被引：5，自引：14，他引：5  

邹捍  周立波  马舒坡  李鹏  李爱国  霍翠萍 《高原气象》2007,26(6):1123-1140

青藏高原地-气间的物质/能量交换是高原与全球大气系统相联系的重要纽带.陡峭的地形和强烈的地表差异在高原山区形成特殊的局地大气环流系统,在地气交换中起着重要作用.为研究珠峰北坡的局地环流系统,于2006年5～6月间在珠峰北坡绒布河谷实施强化观测实验HEST2006,对该地区的局地环流以及辐射和热力状况进行观测,分析了该地区局地环流的日变化过程,包括:(1)地面风场的分布和变化;(2)风场垂直结构;(3)垂直运动及可能的驱动机制.研究表明,该地区局地大气环流是由地形与地表状态调整的大气辐射加热和冷却所驱动,包含多种不同的山地环流成分,与典型山谷风环流不同,具有很强的特殊性,对地气问的交换有重要影响.  相似文献   

Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf   总被引：4，自引：0，他引：4  

Kenneth C. JEZEK  Beata M. CSATHó  Ute C. HERZFELD  Katy L. FARNESS  Philippe HUYBRECHTS 《中国科学D辑(英文版)》2007,50(11):1693-1706

We used in situ measurements and remote-sensing data sets to evaluate the mass budgets of the Lambert, Mellor and Fisher Glaciers and the basal melting and freezing rates beneath their flowbands on the Amery Ice Shelf. Our findings show the Lambert and Mellor Glaciers upstream of the ANARE Lambert Glacier Basin (LGB) traverse may have positive imbalances of 3.9±2.1 Gt a-1 and 2.1±2.4 Gt a-1, respectively, while the Fisher Glacier is approximately in balance. The upstream region as a whole has a positive imbalance of 5.9±4.9 Gt a-1. The three same glaciers downstream of the ANARE LGB traverse line are in negative imbalance, where the whole downstream region has a negative imbalance of -8.5±5.8 Gt a-1. Overall the mass budgets of the Lambert, Mellor, and Fisher Glaciers are close to bal-ance, and the collective three-glacier system is also nearly in balance with a mass budget of -2.6±6.5 Gt a-1. The significant positive imbalances for the interior basin upstream of the ice-movement stations established in the early 1970s (GL line) reported previously are possibly due to an overestimate of the total accumulation and an underestimate of the ice flux through the GL line. The mean melting rate is -23.0±3.5 m ice a-1 near the southern grounding line, which decreases rapidly downstream, and transitions to refreezing at around 300 km from the southern extremity of the Amery Ice Shelf. Freezing rates along the flowbands are around 0.5±0.1 to 1.5±0.2 m ice a-1. The per-centage of ice lost from the interior by basal melting beneath the flowbands is about 80%±5%. The total basal melting and refreezing beneath the three flowbands is 50.3±7.5 Gt ice a-1 and 7.0±1.1 Gt ice a-1, respectively. We find a much larger total basal melting and net melting than the results for the whole Amery Ice Shelf derived from previous modeling and oceanographic measurements.  相似文献   

Monitoring Changes of Ice Streams Using Time Series of Satellite-Altimetry-Based Digital Terrain Models     

Ute C. Herzfeld  Craig S. Lingle  Cecily Freeman  Chris A. Higginson  Michael P. Lambert  Li-Her Lee  Vera A. Voronina 《Mathematical Geology》1997,29(7):859-890

The Antarctic Ice Sheet plays a major role in the global system, and the large ice streams discharging into the circumpolar sea represent its gateways to the world's oceans. Satellite radar altimeter data provide an opportunity for mapping surface elevation at kilometer-resolution with meter-accuracy. Geostatistical methods have been developed for the analysis of these data. Applications to Seasat data and data from the Geosat Exact Repeat Mission indicate that the grounding line of Lambert Glacier/Amery Ice Shelf, the largest ice stream in East Antarctica, has advanced 10–12 km between 1978 and 1987–89. The objectives of this paper are to explore possibilities and limitations of satellite-altimetry-based mapping to capture changes for shorter time windows and for smaller areas, and to investigate some methodological aspects of the data analysis. We establish that one season of radar altimeter data is sufficient for constructing a map. This allows study of interannual variation and is the key for a time-series analysis approach to study changes in ice streams. Maps of the lower Lambert Glacier and the entire Amery Ice Shelf are presented for austral winters 1978, 1987, 1988, and 1989. As a first step toward understanding the dynamics of the ice-stream/ice-shelf system, elevation changes are calculated for grounded ice, the grounding zone, and floating ice. In the absence of (sufficient) surface gravity control for the Lambert Glacier/Amery Ice Shelf area, altimetry-based maps may facilitate improvement of geoid models as they provide constraints on the terrain correction in the inverse gravimetric problem.  相似文献   

Deglaciation and Holocene climate change in the western Peruvian Andes     

Chengyu Weng  Mark B. Bush  Tom D. Dillehay  Michael W. Binford 《Quaternary Research》2006,66(1):87-96

  相似文献   

天山乌鲁木齐河源1号冰川对降水影响的定量分析   总被引：5，自引：2，他引：3  

张东启  周尚哲 《冰川冻土》2000,22(3):243-249

以天山乌鲁木齐河源１号冰川为例,系统地分析了冰川区降水的形成因素,阐述了冰川作为特殊性质的下垫面对降水产生影响的机制,并定量化地计算出了乌鲁木齐河源１号冰川对降水的贡献,冰川作为特殊性质下垫面对降水产生影响,其主要是通过致冷效应以及由此引起发的温跃现象、逆温现象、冰川风现象、凝结高度降低现象和水平降水现象的作用来实现的,乌鲁木齐河源１号冰川作为特殊性质的下垫面对年降不的贡献比重随高度的不同而变化。  相似文献   

冰川消融对气候变化的响应——以乌鲁木齐河源1号冰川为例   总被引：19，自引：10，他引：9  

李忠勤  沈永平  王飞腾  李慧林  董志文  王文彬  王林 《冰川冻土》2007,29(3):333-342

目前气候变暖导致的冰川退缩,引起了广泛关注.以新疆天山乌鲁木齐河源1号冰川为例,根据1959年以来的观测资料,研究了冰川消融对气候变化的响应.结果表明:近50 a来冰川在表面粒雪特征、成冰带、冰川温度、面积、厚度及末端位置等方面发生了显著变化,而这些变化均与气温的升高有着密切的联系;冰川的退缩自20世纪80年代后,尤其是近10 a来出现了加速趋势.其原因除夏季气温升高外,还有两个重要因素,一是冰川温度升高造成冷储的减少,二是冰川表面反射率下降导致辐射能量接收的增强.冰川物质平衡在1986年之前由气温和降水共同决定,之后主要受气温控制.  相似文献   

青藏高原中部扎当冰川物质平衡研究   总被引：5，自引：4，他引：1  

周广鹏  姚檀栋  康世昌  蒲健辰  田立德  杨威 《冰川冻土》2007,29(3):360-365

最新观测表明,青藏高原扎当冰川2005/2006年度物质平衡量为-306.42×10⁴m³,相当于-1547.57 mm水当量,冰面出现显著的减薄.扎当冰川出现如此大的负平衡在青藏高原中部地区实属罕见,这可能与影响冰川物质平衡过程的区域气候状况和局地气候因素的差异有关系.物质平衡出现较大的负值和零平衡线位置升高的状况,强烈反映了扎当冰川对气候变暖过程的响应.  相似文献