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南极洲巨型冰山断裂,冰雪大陆形状永久改变

更新时间:2017-7-13 12:00:21 来源:纽约时报中文网 作者:佚名

An Iceberg the Size of Delaware Just Broke Off a Major Antarctic Ice Shelf
南极洲巨型冰山断裂,冰雪大陆形状永久改变

A chunk of floating ice that weighs more than a trillion metric tons broke away from the Antarctic Peninsula, producing one of the largest icebergs ever recorded and providing a glimpse of how the Antarctic ice sheet might ultimately start to fall apart.

一块重量超过1万亿吨的巨大浮冰从南极半岛断裂,形成了有记录以来的最大冰山之一,也为南极冰架最终也许会怎样崩解提供了一瞥。

A crack more than 120 miles long had developed over several years in a floating ice shelf called Larsen C, and scientists who have been monitoring it confirmed on Wednesday that the huge iceberg had finally broken free.

名为拉森C的冰架在几年的时间里已经逐渐现出一条长达120英里(约合193公里)的大裂缝,一直在监测这条裂缝的科学家周三证实,巨大的冰山终于从冰架断裂出来。

There is no scientific consensus over whether global warming is to blame. But the landscape of the Antarctic Peninsula has been fundamentally changed, according to Project Midas, a research team from Swansea University and Aberystwyth University in Britain that had been monitoring the rift since 2014.

全球变暖是否是这次断裂的罪魁祸首,目前科学上尚无共识。但来自英国斯旺西大学(Swansea University)和阿伯斯威斯特大学(Aberystwyth University)的迈达斯计划(Project Midas)研究小组说,南极半岛的形状已经彻底改变,该小组自2014年起,一直在监测这条裂缝。

“The remaining shelf will be at its smallest ever known size,” said Adrian Luckman, a lead researcher for Project Midas. “This is a big change. Maps will need to be redrawn.”

“剩下的冰架将处于有记录以来的已知最小规模,”迈达斯计划的首席研究员艾德里安·拉克曼(Adrian Luckman)说。“这是一个极大的变化。需要重新绘制地图。”

Larsen C, like two smaller ice shelves that collapsed before it, was holding back relatively little land ice, and it is not expected to contribute much to the rise of the sea. But in other parts of Antarctica, similar shelves are holding back enormous amounts of ice, and scientists fear that their future collapse could dump enough ice into the ocean to raise the sea level by many feet. How fast this could happen is unclear.

与此前崩解的两个较小冰架一样,拉森C冰架几乎没有阻挡多少陆上冰,所以其崩解预计不会对海平面的上升产生多大影响。但在南极的其他地区,类似的冰架正阻挡着大量的冰川,科学家们担心,这些冰架的未来崩解可能会将足够多的冰倾入海洋,从而导致海平面上升1米以上。这种情况可能多么快地发生目前尚不清楚。

In the late 20th century, the Antarctic Peninsula, which juts out from the main body of Antarctica and points toward South America, was one of the fastest-warming places in the world. That warming had slowed or perhaps reversed slightly in the 21st century, but scientists believe the ice is still catching up to the higher temperatures.

20世纪末,从南极主体向南美洲方向伸出的南极半岛是世界上温度增长最快的地区之一。虽然这种变暖已经在21世纪放缓或可能略有逆转,但科学家认为,冰的温度尚未达到半岛地区的更高温度。

Some climate scientists believe the warming in the region was at least in part a consequence of human-caused climate change, while others have disputed that, seeing a large role for natural variability — and noting that icebergs have been breaking away from ice shelves for many millions of years. But the two camps agree that the breakup of ice shelves in the peninsula region may be a preview of what is in store for the main part of Antarctica as the world continues heating up as a result of human activity.

一些气候科学家认为,该地区的变暖至少部分是人为气候变化的结果,但也有一些气候科学家对这种观点持异议,认为自然的多变性在其中起着更大的作用,他们指出,冰山从冰架上脱离的事情在数百万年间时有发生。但是,这两个阵营的人都一致认为,半岛地区冰架的断裂,可能预示了等待着南极主体的未来,因为地球由于人类活动在不断升温。

“While it might not be caused by global warming, it’s at least a natural laboratory to study how breakups will occur at other ice shelves to improve the theoretical basis for our projections of future sea level rise,” said Thomas P. Wagner, who leads NASA’s efforts to study the polar regions.

在美国宇航局领导极地研究项目的托马斯·P·瓦格纳(Thomas P. Wagner)说:“虽然这可能不是全球变暖造成的,但它至少为研究其他冰架将如何崩解提供了一个自然实验室,有助于改进我们预测未来海平面上升的理论基础。”

In frigid regions, ice shelves form as the long rivers of ice called glaciers flow from land into the sea. The result is a bit like a clog in a drain pipe, slowing the flow of the glaciers feeding them. When an ice shelf collapses, the glaciers behind it can accelerate, as though the drain pipe had suddenly cleared.

在寒冷地区,名为冰川的长冰河从陆地流入海洋形成了冰架。其结果有点像排水管发生了堵塞,减慢了供给冰架的冰川的流速。当冰架出现崩解时,其后面的冰川的滑动可能会加速,就好像排水管突然畅通了。

At the remaining part of Larsen C, the edge is now much closer to a line that scientists call the compressive arch, which is critical for structural support. If the front retreats past that line, the northernmost part of the shelf could collapse within months.

拉森C冰架剩余部分的边缘现在与科学家称之为“褶皱弧”的界线更接近了,褶皱弧对结构稳定性至关重要。如果冰川的前沿退到了这条线的后边,那么冰架的最北部分可能会在几个月内崩解。

“At that point in time, the glaciers will react,” said Eric Rignot, a climate scientist at the University of California, Irvine, who has done extensive research on polar ice. “If the ice shelf breaks apart, it will remove a buttressing force on the glaciers that flow into it. The glaciers will feel less resistance to flow, effectively removing a cork in front of them.”

“到那时,冰川会有所反应,”加州大学尔湾分校的气候科学家埃里克·里格诺特(Eric Rignot)说,他对极地冰做过广泛的研究。“如果冰架破碎,它将消除对流入其中的冰川的支撑。冰川流动的阻力会变得更小,等于是把挡在它前面的塞子拿掉了。”

Scientists also fear that two crucial anchor points will be lost.

科学家们也担心将会失去两个关键的固定点。

According to Dr. Rignot, the stability of the whole ice shelf is threatened, as the shelf front thins.

里格诺特说,随着冰架的前部变薄,整个冰架的稳定性受到威胁。

“You have these two anchors on the side of Larsen C that play a critical role in holding the ice shelf where it is,” he said. “If the shelf is getting thinner, it will be more breakable, and it will lose contact with the ice rises.”

“拉森C冰架这边有这两个固定点,它们对把冰架保持在现有位置上起着关键作用,”他说。“如果冰架变得越来越薄,就更容易断裂,并会失去与冰隆的接触。”

Ice rises are islands that are overridden by the ice shelf, allowing them to shoulder more of the weight of the shelf. Scientists have yet to determine the extent of thinning around the Bawden and Gipps ice rises, though Dr. Rignot noted that the Bawden ice rise was more vulnerable.

冰隆是冰架覆盖下的岛屿,它们能承担更多的冰架重量。科学家尚未确定鲍登冰隆和吉普斯冰隆周围的变薄程度,但里格诺特指出,鲍登冰隆已经更加脆弱。

“We’re not even sure how it’s hanging on there,” he said. “But if you take away Bawden, the whole shelf will feel it.”

“我们就连目前那里的什么东西在支撑着冰架都不确定,”他说。“但如果没有鲍登的话,整个冰架都会感觉到。”

The Antarctic Peninsula may be a canary in a coal mine.

南极半岛可能是煤矿里的金丝雀。

The collapse of the peninsula’s ice shelves can be interpreted as fulfilling a prophecy made in 1978 by a renowned geologist named John H. Mercer of Ohio State University. In a classic paper, Dr. Mercer warned that the western part of Antarctica was so vulnerable to human-induced climate warming as to pose a “threat of disaster” from rising seas.

南极半岛冰架的崩解可以被解释为俄亥俄州立大学著名地质学家约翰·H·默瑟(John H. Mercer)1978年所做预言的兑现。默瑟在一篇经典论文中警告说,南极西部对人类造成的气候变暖如此之脆弱,以至于该地区构成对海平面上升所致“灾难的威胁”。

He said that humanity would know the calamity had begun when ice shelves started breaking up along the peninsula, with the breakups moving progressively southward.

他说,当冰架开始沿着半岛崩解、而且崩解逐步向南扩展时,人类将会知道灾难已经到来。

The Larsen A ice shelf broke up over several years starting in 1995; the Larsen B underwent a dramatic collapse in 2002; and now, scientists fear, the calving of the giant iceberg could be the first stage in the breakup of Larsen C.

拉森A冰架已从1995年开始在几年的时间里崩解了。拉森B冰架在2002年发生了突然的崩溃。现在,科学家们担心,巨大冰山的脱落可能是拉森C冰架崩解的第一个阶段。

“As climate warming progresses farther south,” Dr. Rignot said, “it will affect larger and larger ice shelves, holding back bigger and bigger glaciers, so that their collapse will contribute more to sea-level rise.”

里格诺特说,“随着气候变暖进一步向南发展,受其影响的冰架将越来越大,挡在这些冰架后面的冰川也越来越大,因此,这些冰架的崩解将对海平面的上升有更大的影响。”

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