冰盖资料

冰盖，是一块巨型的圆顶状冰，覆盖着广大地区的极厚的冰层，覆盖少于50000平方公里的陆地面积（一般常见于高原地区），覆盖面积超过50000平方公里的叫做冰原。

一般指大陆冰川，南极和格陵兰为两个大冰盖。

冰盖是指长期覆盖在陆地上的面积大于5万平方千米的冰体。

又称大陆冰川，简称冰盖。

南极冰盖始于渐新世末。

至少在距今500万年前就达到目前规模。

冰盖绝大部分分布在南极圈内，直径约4500千米，面积约1398万平方千米，约占南极大陆面积的98％。

平均厚度为2000～2500米，最大厚度达4000多米。

冰盖的总体积约245 0万立方千米，占世界陆地冰量的90％，淡水总量的70％。

冰盖外围发育有面积约为150多万平方千米的陆缘冰，主要有罗斯冰架、菲尔希纳冰架和埃默里冰架等。

在内陆冰盖的补给和推动下，冰架边缘不断崩坍出大量的平顶冰山。

格陵兰冰盖形成于第四纪，在距今约18000年时冰盖面积比今面积大7倍，并与当时北美冰盖相连接。

格陵兰岛大部分位于北极圈内，全岛面积为218万平方千米，是世界最大的岛屿。

格陵兰冰盖面积约180万平方千米，平均厚度约1500米，最大厚度达3200米，占世界冰量的7％～9％。

它由南北两个穹形冰盖连结而成，冰盖边缘一直覆盖到海边，有许多冰川的冰舌伸向海面，在若干峡湾中形成许多冰山。

西格陵兰的一些冰川，如雅各布港·伊斯伯依冰川，每年流动速度达7000米，是世界上流动最快的冰川。

冰盖中部西侧的冰层表面每年以0.1米的速率在增厚，而东侧则稍有变薄。

冰盖西海岸的消融区冰面每年变薄约0.2米。

世界冰川分布(从百度中复制自己产生)冰川在世界两极和两极至赤道带的高山均有分布，地球上陆地面积的1/10为冰川所覆盖，而4/5的淡水资源就储存于冰川(冰盖)之中[1]。

现代冰川在世界各地几乎所有纬度上都有分布。

地球上的冰川，大约有2900多万平方公里，覆盖着大陆11%的面积。

冰川冰储水量虽然占地球总水量的2％，储藏着全球淡水量的3/4左右，但可以直接利用的很少。

现代冰川面积的97％、冰量的99％为南极大陆和格陵兰两大冰盖所占有，特别是南极大陆冰盖面积达到1398万平方公里(包括冰架)，最大冰厚度超过4000米，冰从冰盖中央向四周流动，最后流到海洋中崩解。

中国冰川分布在新疆、青海、甘肃、四川、云南和西藏6省区。

其中西藏的冰川数量多达22468条，面积达28645平方公里。

中国冰川自北向南依次分布在阿尔泰山、天山、帕米尔高原、喀喇昆仑山、昆仑山和喜马拉雅山等14条山脉。

这些山脉山体巨大，为冰川发育提供了广阔的积累空间和有利于冰川发育的水热条件。

通过考察发现，中国冰川面积中大于100平方公里的冰川达33条，其中完全在中国境内最大的山谷冰川是音苏盖提冰川，面积为392.4平方公里，最大的冰原是普若岗日，面积达423平方公里，最大的冰帽是崇测冰川，面积达163平方公里[1]。

中国冰川分布图（从百度中复制自己产生）中国山岳冰川按成因分为大陆性冰川和海洋性冰川两大类。

总储量约51300亿立方米。

前者占冰川总面积的80%，后者主要分布在念青唐古拉山东段。

按山脉统计，昆仑山、喜马拉雅山、天山和念青唐古拉山的冰川面积都超过7000平方千米，四条山脉的冰川面积共计40300平方千米，约占全国冰川总面积的70%，其余30%的冰川面积分布与喀喇昆仑山、羌塘高原、帕米尔、唐古拉山、祁连山、冈底斯山、横段山及阿尔泰山。

大陆冰盖主要分布在南极和格陵兰岛。

山岳冰川则分布在中纬、低纬的一些高山上。

全世界冰川面积共有l500多万平方公里，其中南极和格陵兰的大陆冰盖就占去1 465万平方公里。

面积超过14,000,000平方公里的南极洲，差不多全部都被一个平均接近1,980米厚的冰川覆盖着，其东部冰层厚度可达4267米。

格陵兰冰盖覆盖的面积超过1,800,000平方公里，实测最大厚度约3,350米。

较小的大陆冰盖常被称作冰帽或冰原。

地球上有两大冰盖，即南极冰盖和格陵兰冰盖，它们占世界冰川总体积的99％，其中南极冰盖占90％。

格陵兰约有83％的面积为冰川覆盖。

因此，山岳冰川与大陆冰盖相比，规模极为悬殊。

巨大的大陆冰盖上，漫无边际的冰流把高山、深谷都掩盖起来，只有极少数高峰在冰面上冒了一个尖，辽阔的南极冰盖，过去一直是个谜，深厚的冰层掩盖了南极大陆的真面目。

科学家们用地球物理勘探的方法发冰川景象现，茫茫南极冰盖下面有许多小湖泊，而且这些湖泊里还有生命存在。

我国的冰川都属于山岳冰川。

就是在第四纪冰川最盛的冰河时代，冰川规模大大扩大，也没有发育为大陆冰盖。

以前有很多专家认为，青藏高原在第四纪的时候曾经被一个大的冰盖所覆盖，即使现在国外有些专家仍持这种观点。

但是经过考察和论证，我国的冰川学者基本上否定了这种观点。

按照冰川的物理性质（如温度状况等）分为：①极地冰川，整个冰层全年温度均低于融点；②亚极地冰川，表面可以在夏季融化外，冰层大部分低于融点；③温冰川，除表层冬季冰结外，整个冰层处于压力融点。

极地冰川和亚极地冰川又合称冷冰川，多分布南极和格陵兰。

温冰川主要发育在欧洲的阿尔卑斯山、斯堪的纳维亚半岛、冰岛，阿拉斯加和新西兰等降水丰富的海洋性气候地区。

除了冰体内部的力学、热学相互作用外，冰川作用还表现在它对地表的塑造过程，即冰川的侵蚀、搬运与堆积作用。

Ice sheetFrom Wikipedia, the free encyclopediaJump to: navigation, searchAn ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km²(20,000 mile²),[1]thus also known as continental glacier.[2] The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada and North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet —these are ice streams.The present-day polar ice sheets are relatively young in geological terms. The Antarctic Ice Sheet first formed as a small ice cap (maybe several) in the early Oligocene, but retreating and advancing many times until the Pliocene, when it came to occupy almost all of Antarctica. The Greenland ice sheet did not develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation. This had the unusual effect of allowing fossils of plants that once grew on present-day Greenland to be much better preserved than with the slowly forming Antarctic ice sheet.Contents[hide]∙1Antarctic ice sheet∙2Greenland ice sheet∙3Ice sheet dynamics∙4Predicted effects of global warming∙5References∙6External links[edit] Antarctic ice sheetMain article: Antarctic ice sheetA satellite composite image of AntarcticaThe Antarctic ice sheet is the largest single mass of ice on Earth. It covers an area of almost 14 million km2and contains 30 million km3of ice. Around 90% of the fresh water on the Earth's surface is held in the ice sheet, and, if melted, would cause sea levels to rise by 61.1 meters.[3] The continent-wide average surface temperature trend of Antarctica is positive and significant at >0.05°C/decade since 1957.[4]The Antarctic ice sheet is divided by the Transantarctic Mountains into two unequal sections called the East Antarctic ice sheet (EAIS) and the smaller West Antarctic Ice Sheet (WAIS). The EAIS rests on a major land mass but the bed of the WAIS is, in places, more than 2,500 meters below sea level. It would be seabed if the ice sheet were not there. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.[edit] Greenland ice sheetMain article: Greenland ice sheetMap of Greenland[5]The Greenland ice sheet occupies about 82% of the surface of Greenland, and if melted would cause sea levels to rise by 7.2 metres.[3] Estimated changes in the mass of Greenland's ice sheet suggest it is melting at a rate of about 239 cubic kilometres (57.3 cubic miles) per year.[6] These measurements came from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite, launched in 2002, as reported by BBC News in August 2006.[7][edit] Ice sheet dynamicsMain article: Ice sheet dynamicsIce movement is dominated by the motion of glaciers, whose activity is determined by a number of processes.[8]Their motion is the result of cyclic surges interspersed with longer periods of inactivity, on both hourly and centennial time scales.[edit] Predicted effects of global warmingThe Greenland, and probably the Antarctic, ice sheets have been losing mass recently, because losses by melting and outlet glaciers exceed accumulation of snowfall. According to the Intergovernmental Panel on Climate Change (IPCC), loss of Antarctic and Greenland ice sheet mass contributed, respectively, abou t 0.21 ± 0.35 and 0.21 ± 0.07 mm/year to sea level rise between 1993 and 2003.[9]The IPCC projects that ice mass loss from melting of the Greenland ice sheet will continue to outpace accumulation of snowfall. Accumulation of snowfall on the Antarctic ice sheet is projected to outpace losses from melting. However, loss of mass on the Antarctic sheet may continue, if there is sufficient loss to outlet glaciers. In the words of the IPCC, "Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise. Understanding of these processes is limited and there is no consensus on their magnitude."More research work is therefore required in order to improve the reliability of predictions of ice-sheet response on global warming.。