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The Heard Island glaciers covered 79 percent of Heard Island itself, in 1947, covering 288 km2; by 1988, this had decreased by 11 percent to 257 km2.〔http://www.antarctica.gov.au/about-antarctica/australian-antarctic-magazine/issue-2-spring-2001/science/glaciology/our-subantarctic-glaciers-why-are-they-retreating〕 The glaciers fall under the Antarctic Environmental Gradient, which spans 30 degrees of latitude and includes a range of macro-climatic zones from cool temperate islands to the frigid and arid Antarctic continent.〔http://www.heardisland.aq/history/research-expeditions/australian-research-expeditions〕Glaciers extend from 2745 m to sea level, with ice up to 150 m deep.The geologic movement of the glaciers can appear fast-flowing due to the steep slope and high precipitation, and are particularly sensitive to climatic fluctuations. Measurements between 1947 and 1980 show glacial retreat, particularly on the eastern flanks, is correlated with changes in weather patterns.〔http://www.eoearth.org/article/Heard_Island_and_McDonald_Islands,_Australia#gen5〕 A 29% reduction in area of the Brown Glacier from 1947-2003 was observed.〔http://glacierchange.wordpress.com/2010/11/04/stephenson-glacier-retreat-heard-island/〕 The volcano Big Ben, from which all the glaciers drain, has shown no sign of changing geothermal output to cause the melting;〔 a 1 degree Celsius warming has occurred over the same time period.〔 Glaciologists continue to study the Brown Glacier, detailing surveys of the glacier's snout and surface, which determine if glacial retreat is rapid or punctuated.〔 Measurements on the mass balance of the glacier, as well as more detailed ice thickness measurements using a portable radar echo sounder, were undertaken.〔 Monitoring of climatic conditions continues, with emphasis on the impact of Foehn winds on glacier mass balance. An expedition by scientists from the Australian Antarctic Division recently visited the volcanic island in 2009, observing glaciers that had retreated 50 metres in three years. Repairs were made to an automatic weather station established in November 2000.〔 Glaciologist Dr. Ian Allison cites that the latest aerial surveys that show continuous rapid melt and that satellite imagery shows the island double in size due to volcanic activity.〔http://www.abc.net.au/news/stories/2009/01/16/2467263.htm〕 ==Glacier Changes== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Heard Island glaciers」の詳細全文を読む スポンサード リンク
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