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At the height of the summer melt, the Arctic Ocean's ice sheet had shrunk to an area of 3.41m square kilometres, half what it was in 1979.
随着夏日的深入，北冰洋的冰原面积缩减到341万平方公里，该数字仅为1979年同期面积的二分之一。
And its volume had shrunk faster still, to a quarter of what it was in 1979, for the sheet is getting thinner as well as smaller.
同时，就冰原体积而言，目前北极冰原的体积仅为1979年的四分之一，其融化速度之快可想而知。如今的北极地区，不仅冰原的面积在减少，其体积也在缩小。
One culprit is global warming, whic
h is fiercer at the poles than elsewhere.
而这一现象的罪魁祸首便是全球变暖。同时，相比于其他海域而言，全球变暖对两极地区的冲击尤为明显。
The world's average temperature in 2012 was nearly 0.5C above the average for 1951-80.
与1951-1980年相比，2012年全球均温上涨了0.5，
In the Arctic, it was up almost 2C.
其中仅北极地区便上涨了2。
This sudden warming is like the peeling back of a lid to reveal a new ocean underneath.
就如同是掀开了某个锅盖后发现了一片沸腾的海洋一般，全球温度骤然上升。
That prospect is spreading alarm and excitement.
全球变暖加剧的前景不仅使人深感担忧，也使人倍觉振奋。
Though most of the excitement has been about oil and gas, and the opening of sea routes between the Atlantic and the Pacific, some people hope for a fishing bonanza, too, as warmth and light bring ecological renewal to what is now an icy desert.
尽管大多数的掌声来自油气开发商与大西洋-太平洋朗阁拥护者，然而由于全球变暖给这片冰雪荒原带来了温暖与阳光，为其生态环境注入了新的元素，不少人也梦想着在这里靠捕鱼发一笔横财，
But they may be disappointed.
只是后者很可能会抱憾而归。
At the moment, the waters around the Arctic account for a fifth of the world's catch.
目前，北极地区占有全球总水量的五分之一。
There are few fish, however, under the ice itself.
然而在这厚厚的冰层下，却鲜有鱼类问津。
A fishing bonanza would require big ecological change.
在北极生态系统完全改变之前，捕鱼或许不是当地的最佳致富之道。
Arctic Frontiers, a conference organised at the University of Tromso in January, looked at how warming will change the ecology, to estimate whether it will bring one about.
1月，挪威特罗姆瑟大学召开“北极边境”会议，专门研究全球变暖对已有生态环境的影响，以及预估该现象是否会促进生成一个新的生态环境。
The consensus was that it won't—not because the Arctic will change too little, but because it will change too much.
会上，与会代表达成共识：北极海域将不会形成新的生态环境，这并不是因为北极的改变不足挂齿，恰恰相反，而是因为这里将会发生翻天覆地的变化。
Change and decay
变化与衰退
At first sight, this is counterintuitive.
乍读此言，不免觉得有些互相矛盾。
As the ice melts, more light can reach the water, and that means more photosynthesis by marine algae.
然而随着冰层进一步融化，大量阳光直射海面，海水中藻类植物的光合作用将会大大增强。
In the past, algae began to grow under the ice sheet in May and continued to do so until late September.
过去，冰原下的海藻于每年五月开始生长，至九月末结束，
Now, such growth starts in mid-March and continues until October.
但现在海藻的生长期已延长为每年三月中旬至十月。
These ice algae, attached to the sheet itself, account for half the mass of living things in Arctic waters.
在所有北极海洋生物中，约半数生物为此类附着在冰原下方的冰藻，
Much of the rest is unattached algae, known as phytoplankton, and tiny animals, known as zooplankton.
另外还有部分浮游植物及浮游动物，
Both sorts of plankton support, directly or indirectly, the fish and mammals that live in the Arctic Ocean.
而这两类浮游生物便是北极地区鱼类及哺乳动物直接或间接的养料来源。
And the plankton, too, are flourishing thanks to global warming.
此外，全球变暖也使得此类浮游生物的数量激增：
The Arctic phytoplankton bloom, which used to run from June to September, now runs from April to September.
北极浮游植物生长期已经由过去的六至九月延长到了四至九月。
The upshot is more plankton, farther north.
于是，随着浮游生物进一步向北部蔓延，
That attracts more fish.
更多鱼类被吸引至此。
In 2000 Atlantic cod were caught throughout the Barents Sea.
2000年，巴伦支海南北遍布大西洋鳕鱼;
By 2012 their distribution was skewed towards the northern part of that sea.
2012年，大西洋鳕鱼活动范围北移至巴伦支海北部。
Stocks of capelin used to be concentrated south of Svalbard, at latitude 75N.
同时，曾主要分布于北纬75斯瓦尔巴群岛海域的capelin，
In 2012 this had moved to 78N.
于2012年被发现已迁移至北纬78附近，
Some found their way as far up as 80N.
部分甚至已迁徙到北纬80附近海域。
Which all sounds most promising. But many researchers think it will not continue.
尽管种种迹象表明在此地捕鱼致富的前景颇为乐观，然而许多学者却持不同意见。
First, the central Arctic is too deep for some important species, such as the polar cod.
首先，北冰洋中部海水过深，不利于极地鳕鱼等重要物种的生存。
Young polar cod are pelagic, meaning they live at or near the surface.
极地鳕鱼与大西洋鳕鱼同属，但前者活动范围较后者更为偏北。
Those one or more years old are benthic, meaning they live near the bottom.
此外，极地鳕鱼的幼鱼为海面鱼，这些幼鱼仅在海面附近活动;一岁及以上的极地鱼为深海鱼，这些深海鱼仅生活在类似于博福尔海域的海底。
In the Beaufort that bottom is 200 metres down.
鉴于博福尔海的深度为200米，
In the central Arctic it descends to about 4,000 metres, which is too deep for polar cod to survive.
而北冰洋中部深度约为4000米，因此极地鳕鱼根本无法在北极地区生存。
A second reason why there may be no bonanza is acidification of the ocean.
其次，北冰洋的酸化现象也是此地不宜鱼类生存的重要原因。
When water absorbs carbon dioxide, it produces carbonic acid. More CO?
水吸收二氧化碳后会释放出碳酸，
means oceans everywhere are becoming more acidic, but the phenomenon is particularly marked at high latitudes because cold water absorbs CO? more readily than warm water does.
因此，随着二氧化碳排放量增加，海水酸度也会随之升高。另外，因为冷水比热水更易吸收二氧化碳，所以这种现象在高纬度地区尤为明显。
The retreat of the ice also exposes ever more sea to do the absorbing.
于是，冰原面积的锐减也意味着更多的低温洋面将会暴露在空气之中，吸收大量的二氧化碳。
Cruises by the United States Ge
