2008/06/27, NOWnews 國際中心綜合報導
http://tw.news.yahoo.com/article/url/d/a/080627/17/123v0.html
溫室效應造成的下場,可能在今年夏天就會降臨。英國媒體報導,北極冰帽的冰層消失速度相當快,而且冰層變薄,融化速度倍增,科學家警告,今年夏季北極冰帽很可能變成沒有冰山、一片汪洋的可怕景象,上升的海平面,對於低窪的城市威脅迫在眉睫。
北極的冰架崩塌現場傳出巨大的聲響,原本這些都是大自然的現象,但受到地球暖化的影響,北極的冰山不但急速減少,今年夏天甚至會出現沒有冰的情況。
美國科羅拉多州的科學家警告,由於厚的冰層流失過多,新形成的冰層厚度不夠,夏天溫度上升加速新的冰層融化,預估多達7成新的冰層夏天前就會全部融化,融化的水流到大海,海平面低的地區就會面臨電影中海水淹沒城市的可怕的景象。
去年就有專家提出警告,地球的二氧化碳的排放量再不減少,2015年之前,至少20個沿海的大城市受到水位上升的威脅,包括曼谷、東京和上海都名列其中。泰國災難警告中心主任也曾表示,「泰國(曼谷)將會在15到20年後被海水淹沒」。
北極沒有冰,首當其衝的就是北極熊的生存問題,事實上,北極傳出藏有豐富的原油、天然氣,冰層越薄開採越容易,包括美國、俄羅斯、加拿大、挪威和丹麥都在爭奪北極主權,但北極沒有冰的下場,恐怕比開採天然資源更加重要,北極的未來也決定人類的前途。
代誌大條 9月前北極冰恐消失
2008/06/28, www.chinatimes.com 閻紀宇綜合報導
http://tw.news.yahoo.com/article/url/d/a/080628/4/12527.html
全球暖化、溫室效應的威力,北極海的冰層最清楚。美國國家冰雪資料中心(NSIDC)科學家塞瑞茲26日指出,今年9月夏天結束之前,北極(地理北極)可能出現一幅人類從未見識過的曠古奇觀:只見茫茫海水,不見雪白冰層。
塞瑞茲說:「我們中心的同仁還設了一個賭局,賭的就是北極的海冰會不會在今年夏天完全消融;目前看來機率是50%…就科學觀點而言,北極不過就是地球上的一點,然而這地方有它的象徵意義。」他並指出未來幾十年內,北極海冰層恐怕都無法恢復舊觀。
至少70%融化殆盡
去年夏天北極海冰層的消融面積就創下歷史紀錄,9月時水─冰界線退至距離北極約只有1130公里處,沿著阿拉斯加與加拿大外海前行、穿過格陵蘭島西岸直抵大西洋「西北航道」,竟然首度短暫開通。
今年冰層的情況更不樂觀,多個冬季累積的「多年冰」蕩然無存,北極只見上一個冬季才形成的「一年冰」。這些單薄的冰層是否能撐過接下來3個月的夏日艷陽,恐怕大有問題。科學家預估,至少70%的一年冰會在9月前融化殆盡。
未來兩個月是關鍵
塞瑞茲表示,接下來2個月的氣候狀態,將決定北極冰層會不會全部消失。華盛頓大學的林賽教授則指出,風力變化與日照時間都是關鍵因素,今年夏天北極冰層的命運如何,目前還難下斷論。
北極向來是溫室效應最顯著的地區之一,而且冰層加速消融之後,深藍色的海水比雪白的冰層更能吸收陽光,進一步加快暖化速率,導致更多冰層消退,形成惡性循環,對整個北極地區影響重大。
科學家與北極地區原住民伊努特人也發現,每年海冰開始碎裂的時間越來越早,範圍越來越大。在阿拉斯加與加拿大班克斯島之間海域形成的「冰間湖」,面積也比以往大了許多。
周邊資源之爭更激烈
冰間湖是海冰中半永久性的無冰水面區,會吸收太陽熱量,加速海冰邊緣融化。
另一方面,北極冰層消失其實也會帶來一些好處,例如讓西北航道維持長時間暢通,大幅縮短北太平洋與北大西洋之間的航程。此外海冰一旦融化,這片海域中的油田、天然氣田和漁場也將更容易開發。只不過如此一來,自然生態必然遭受嚴重衝擊,而且北極圈周邊諸國的領海與資源之爭也將日益激烈。
Exclusive: No ice at the North Pole
Polar scientists reveal dramatic new evidence of climate change
Friday, 27 June 2008
http://www.independent.co.uk/environment/climate-change/exclusive-no-ice-at-the-north-pole-855406.html
It seems unthinkable, but for the first time in human history, ice is on course to disappear entirely from the North Pole this year.
The disappearance of the Arctic sea ice, making it possible to reach the Pole sailing in a boat through open water, would be one of the most dramatic – and worrying – examples of the impact of global warming on the planet. Scientists say the ice at 90 degrees north may well have melted away by the summer.
"From the viewpoint of science, the North Pole is just another point on the globe, but symbolically it is hugely important. There is supposed to be ice at the North Pole, not open water," said Mark Serreze of the US National Snow and Ice Data Centre in Colorado.
If it happens, it raises the prospect of the Arctic nations being able to exploit the valuable oil and mineral deposits below these a bed which have until now been impossible to extract because of the thick sea ice above.
Seasoned polar scientists believe the chances of a totally ice-free North Pole this summer are greater than 50:50 because the normally thick ice formed over many years at the Pole has been blown away and replaced by huge swathes of thinner ice formed over a single year.
This one-year ice is highly vulnerable to melting during the summer months and satellite data coming in over recent weeks shows that the rate of melting is faster than last year, when there was an all-time record loss of summer sea ice at the Arctic.
"The issue is that, for the first time that I am aware of, the North Pole is covered with extensive first-year ice – ice that formed last autumn and winter. I'd say it's even-odds whether the North Pole melts out," said Dr Serreze.
Each summer the sea ice melts before reforming again during the long Arctic winter but the loss of sea ice last year was so extensive that much of the Arctic Ocean became open water, with the water-ice boundary coming just 700 miles away from the North Pole.
The diminishing polar ice
Courtesy of NOAA / NESDIS Center for Satellite Applications and Research
This meant that about 70 per cent of the sea ice present this spring was single-year ice formed over last winter. Scientists predict that at least 70 per cent of this single-year ice – and perhaps all of it – will melt completely this summer, Dr Serreze said.
"Indeed, for the Arctic as a whole, the melt season started with even more thin ice than in 2007, hence concerns that we may even beat last year's sea-ice minimum. We'll see what happens, a great deal depends on the weather patterns in July and August," he said.
Ron Lindsay, a polar scientist at the University of Washington in Seattle, agreed that much now depends on what happens to the Arctic weather in terms of wind patterns and hours of sunshine. "There's a good chance that it will all melt away at the North Pole, it's certainly feasible, but it's not guaranteed," Dr Lindsay said.
The polar regions are experiencing the most dramatic increase in average temperatures due to global warming and scientists fear that as more sea ice is lost, the darker, open ocean will absorb more heat and raise local temperatures even further. Professor Peter Wadhams of Cambridge University, who was one of the first civilian scientists to sail underneath the Arctic sea ice in a Royal Navy submarine, said that the conditions are ripe for an unprecedented melting of the ice at the North Pole.
"Last year we saw huge areas of the ocean open up, which has never been experienced before. People are expecting this to continue this year and it is likely to extend over the North Pole. It is quite likely that the North Pole will be exposed this summer – it's not happened before," Professor Wadhams said.
There are other indications that the Arctic sea ice is showing signs of breaking up. Scientists at the Nasa Goddard Space Flight Centre said that the North Water 'polynya' – an expanse of open water surrounded on all sides by ice – that normally forms near Alaska and Banks Island off the Canadian coast, is much larger than normal. Polynyas absorb heat from the sun and eat away at the edge of the sea ice.
Inuit natives living near Baffin Bay between Canada and Greenland are also reporting that the sea ice there is starting to break up much earlier than normal and that they have seen wide cracks appearing in the ice where it normally remains stable. Satellite measurements collected over nearly 30 years show a significant decline in the extent of the Arctic sea ice, which has become more rapid in recent years.
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