令人日益惧怕的冰裂，本文主要内容关键词为：，此文献不代表本站观点，内容供学术参考，文章仅供参考阅读下载。
Every summer,massive chunks of ice （some the size of small Pacific islands）break away from the freshwater Antarcticaice shelves which fringe the southernmost continent. Thesegreat ice island's shatter into icebergs which float out tosea.
These annual"calving（注：calve（冰山、冰川）崩裂； 崩解）"events have been getting more frequent and a lot moredramatic.And the scientists who have been observing them areincreasingly worried.
In a letter to the scientific journal Nature,glaciologists （注：[
] 冰川学家）David Vaughan and Chris Doakes from the BritishAntarctic Survey wrote that satellite observations of nine iceshelves on the Antarctic Peninsula south from Argentinashowed that five had "retreated dramatically in the past 50years."
"Ice shelves-appear to be sensitive indicators of climatechange," they wrote.
What is most worrying is that warming of the Antarcticenvironment could have serious implications for the globalecology since the southern ice cover helps regulate globalclimate,ocean circulation and sea level.
Some scientists believe warming of the Southern Ocean andreductions in sea ice could reduce the amount of carbondioxide stored in the oceans each year,possibly acceleratingglobal warming further.
Argentinian scientist Pedro Skvarca, who has also beenwatching the retreat of ice shelves in recent years claimsthe massive Larsen Ice Shelf,on the east coast of theAntarctic Peninsula,decreased by more than 30per cent from1975 to 1989.
Two years ago,a 2,600 sq.km.area of the Larsen lceShelf equivalent in size to the island of Hawaii collapsedand drifted away.This was among the most dramatic and mostextensive ice "calving" events ever observed on the continent.The area of the ice shelf left behind Larsen B undersimilar threat of collapes.
Vaughan and Doakes say recent aerial observation ofLarsen B has found"rifts opening behind the new ice" . Thetwo scientists believe the ice shelves of the AntarcticPeninsula are reaching their "limits of viability （注：生存能力；活力）".
With atmospheric temperatures in the Peninsula increasingslightly each year for the past 20 years,they say the lineat which the ice shelves can exist is gradually retrcatingsouth."It is clear that ice shelves cannot survive periods ofwarming that last more than a few decades," they wrote.
On the other side of the peninsula,the Wordie lce Shelfhas shrunk from around2,000 sq.km.to 700sq.km.between 1966and 1989,according to a paper by Pedro Skvarca and twoAustrian researchers published in the journal Science lastyear.
Erwin Jackson,an Australian climate campaigner （注：（运动）发起人；活动家）,believes the changes being observed inAntarctica rapidly increasing temperatures,disintegration ofAntarctic Peninsula ice shelves and changes in Antarcticbiology are consistent with the predictions for Antarcticamade by an international panel （注：研究小组）of climatescientists in the early 1990s.
"We could shut our eyes and try to wish them (the changes)away,but we might open them again to find there isn't muchto see of what was the last great wilderness," he said.
US President Clinton did not mince his words （注：minceone's words （常用于否定句）说话婉转；转弯抹角）on a visit toAustralia when he signalled his determination to see realaction on climate change."I call upon the community ofnations to agree to legally binding commitments to fightclimate change," he said ."A greenhouse may be a good placeto raise plants ,but it is no place to nurture our children."
每年夏季，巨大的冰块（有些冰块的大小相当于一些太平洋小岛的面积）从南极洲的淡水冰架上断裂开来。这些冰架构成了这个最南部大陆的外围边缘。这些巨大的浮冰岛破碎成冰山，漂流入海。
这些每年一次的“冰解”活动变得越来越频繁，也更剧烈。一直在观察这种活动的科学家们感到越来越担心。
来自英国南极考察队的冰川学家戴维·沃恩和克里斯·多克斯在写给科学杂志《自然》的一封信中写道：据卫星对阿根廷以南南极半岛上九个冰架的观察表明，其中五个“在过去的50年里已经急剧后退。”
“冰架—似乎是天气变化的敏感的指示器，”他们还写道。
更令人担心的是，南极环境变暖可能严重影响全球生态环境，因为南极冰盖有助于调节全球气候、海洋环流和海平面。
有些科学家认为南大洋变暖以及海冰减少可能会使海洋中每年储存的二氧化碳的数量减少，从而有可能进一步加快全球气候变暖。
阿根廷科学家佩德罗·什克瓦尔卡近年来也一直在关注冰架的后退，他认为从1975年至1989年南极半岛东海岸的拉森冰架缩小了30%以上。
两年前，一块面积达2600平方公里的浮冰（相当于夏威夷岛的面积）从拉森冰架上崩裂开来，漂流而去。这是人们观察到的南极大陆上最剧烈、面积最大的“冰解”活动。拉森2 号漂走后剩下的冰架面积也濒临着类似的崩裂威胁。
沃恩和多克斯说，最近对拉森2 号的空中观察发现“新成的冰后面出现了冰裂缺口”。两位科学家认为南极半岛的冰架正在达到其“生存极限”。他们说在过去的20年里，随着南极半岛大气温度逐年一点点上升，冰架存在的界限正在逐渐向南后退。他们写道：“显而易见，在持续几十年的变暖期中，冰架是无法存在的。”
根据佩德罗·什克瓦尔卡和两位奥地利研究人员去年在《科学》杂志上发表的论文，从1966年至1989年，南极半岛另一边的沃迪冰架已经从大约2000平方公里缩小到700平方公里。
澳大利亚气候保护活动家欧文·杰克逊认为：人们现在看到的南极洲温度迅速升高造成的变化、南极半岛冰架的瓦解以及南极生态的变化，与20世纪90年代初国际气象学家研究小组作出的预测是相符的。
他说：“我们可以闭上眼睛，期望它们（这些变化）消失。但是当我们再次睁开眼睛时，可能会发现这最后一块巨大的荒原已经所剩无几了。”
美国总统克林顿在访问澳大利亚期间，明确地表达了要对气候变化采取真正的行动的决心。“我呼吁各国公众一致同意承担必须遵守的法律义务以对付气候变化。”他说，“温室也许是栽种植物的好地方，但那决不是抚育我们后代的好地方。”
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