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Accelerating glaciers contribute to
raised sea
levels。 | |
The impact of climate change on the Antarctic
Peninsula is evident in new satellite data, US researchers say.
The collapse of the Larsen B ice
shelf two years ago has accelerated the flow of glaciers into the nearby Weddell Sea
It is probable the disintegration in 2002 has now allowed the glaciers
to deposit their loads more freely, the team tells Geophysical Research
Letters
The Antarctic Peninsula has seen some of the fastest temperature rises
on Earth in the last five decades.
The scientists used a variety of data from satellites to track the
speed of the glaciers before and after the collapse of Larsen B.
In one study, Ted Scambos of the National Snow and Ice Data Center in
Boulder, US, analysed five images taken by the Landsat 7 satellite between
January 2000 and February 2003.
The analysis reveals that four glaciers flowing into the now collapsed
section of Larsen B increased in speed by between two and six times over
the study period.
"If anyone was waiting to find out whether Antarctica would respond
quickly to climate warming, I think the answer is yes," said Dr Scambos.
The second report, by Eric Rignot of the US space agency's Jet
Propulsion Laboratory in Pasadena, US, showed an eightfold increase in the
speed of three glaciers, called Hektoria, Green and Evans, between 2000
and 2003.
Two others, Jorum and Crane, moved twice as quickly at the beginning of
2003 than they did in 2000 and nearly three times as fast by the end of
the year.
"These two papers clearly illustrate, for the first time, the
relationship between ice shelf collapses caused by climate warming, and
accelerated glacier flow," said Dr Rignot.
The extra ice presumably translates into higher sea level. But how much
this is raising the level of the oceans isn't known.
The authors of the published papers point out that in other places
around the continent, much larger glaciers are also held in check by ice
shelves.
The Antarctic Peninsula is one of the three fastest-warming regions on
Earth - temperatures have risen 2.5 degrees in 50 years.
But the picture generally in Antarctica is complicated, with
temperatures in the interior actually falling over the same period.
There is also some evidence that the retreat of the
West Antarctic ice sheet, on the other side of the peninsula to the
Larsen B shelf, has
halted.
(Agencies) |
美國研究者表示，衛星傳回的新數據顯示，南極半島的氣候變化帶來了顯著的影響。
兩年前崩塌的“守護神B”冰架（巨大的浮動冰層）加快了冰河流入附近的威德爾海的速度。
研究小組對《地球物理研究快報》（Geophysical Research
Letters）表示，可能是因為2002年的冰架解體才使得冰河更容易地聚集了能量。
過去的五十年間，南極半島是地球上氣溫升高最快的地區之一。
科學家們使用衛星發回的各種數據來研究"守護神B"冰架崩塌之前和之后冰河流動的速度。
在一項研究中，美國國家冰雪數據中心（位于博爾德市）的特德·斯坎博斯對美國地球資源探測衛星7號在2000年1月和2003年2月之間拍攝的五幅圖像進行了分析。
分析表明，四條流入“守護神B”冰架現已崩塌部分的冰河在研究期間的流速增加了2至6倍。
斯坎博斯博士說：“如果有人想知道氣候變暖是否很快會對南極洲產生影響，我想答案是肯定的。”
埃里克·里戈諾特供職于美國國家航空航天局設在帕薩迪納市的噴氣推進實驗室，他所做的第二份報告顯示，2000年到2003年間三條分別名為黑克多利亞、格林和埃文斯的冰河的流速增加了8倍。
另外兩條分別名為喬洛姆和克萊恩的冰河在2003年初的流速比2000年增加了一倍，到2003年年底，流速幾乎增加到原來的3倍。
里戈諾特博士說：“這兩份報告第一次清楚地說明了氣候變暖導致的冰架崩塌與冰河流速加快之間的關系。”
可以推測，（冰架崩塌產生的）多余的冰塊會使海平面高度進一步上升，但上升的程度目前尚不可知。
發表上述論文的作者們指出，在南極大陸的其他地區，還有更大的冰河正處在冰架的包圍和阻擋中。
南極半島是地球上溫度升高最快的三個地區之一，其氣溫在50年間上升了2.5
攝氏度。
但是南極洲的總體情況卻很復雜，在因為同一時期內，該地區的地下溫度實際上降低了。
還有一些證據顯示，與“守護神B”冰架隔南極半島相望的西南極洲大冰原已經停止了后退。
（中國日報網站譯） |
Updated: 2004-10-06 08:55