托福雙語閱讀素材：裸露的北極
The Arctic
Polar bare
The Arctic as it is known today is almost certainly gone
北極
裸露的北極
幾乎可以肯定，今天人們熟知的北極已經(jīng)消失
THOSE who doubt the power of human beings to change Earth’s climate should look to the Arctic, and shiver. There is no need to pore over records of temperatures and atmospheric carbon-dioxide concentrations. The process is starkly visible in the shrinkage of the ice that covers the Arctic ocean. In the past 30 years, the minimum coverage of summer ice has fallen by half; its volume has fallen by three-quarters. On current trends, the Arctic ocean will be largely ice-free in summer by 2040.
懷疑人類有多大能耐改變地球氣候的人應(yīng)該看看北極，看過之后他們會不寒而栗。不需要仔細查閱溫度和大氣中二氧化碳濃度的記錄，僅從北冰洋上冰面的日益縮減就可以明顯觀察到這一變化。過去30年，夏季海冰的最小覆蓋面積已經(jīng)縮減了一半，體積縮小了四分之三。按照目前的趨勢，到2040年夏季，北冰洋上的海冰將基本消失。
Climate-change sceptics will shrug. Some may even celebrate: an ice-free Arctic ocean promises a shortcut for shipping between the Pacific coast of Asia and the Atlantic coasts of Europe and the Americas, and the possibility of prospecting for perhaps a fifth of the planet’s undiscovered supplies of oil and natural gas. Such reactions are profoundly misguided. Never mind that the low price of oil and gas means searching for them in the Arctic is no longer worthwhile. Or that the much-vaunted sea passages are likely to carry only a trickle of trade. The right response is fear. The Arctic is not merely a bellwether of matters climatic, but an actor in them.
氣候變化懷疑論者會不以為然。有些人可能還會歡呼：北冰洋如果沒有了冰，亞洲太平洋沿岸與歐美大西洋沿岸之間就有了一條海運捷徑，還有可能勘探到地球上五分之一的未探明油氣資源。但這樣的反應(yīng)大錯特錯。且不說由于石油和天然氣價格低廉，在北極開采已經(jīng)不再劃算，也不論被大肆吹噓的海上通道可能只會承擔(dān)極少的貿(mào)易量，正確的反應(yīng)該是恐懼。北極不僅僅是氣候問題的風(fēng)向標，更是氣候問題的作用因素。
The current period of global warming that Earth is undergoing is caused by certain gases in the atmosphere, notably carbon dioxide. These admit heat, in the form of sunlight, but block its radiation back into space, in the form of longer-wavelength infra-red. That traps heat in the air, the water and the land. More carbon dioxide equals more warming—a simple equation. Except it is not simple. A number of feedback loops complicate matters. Some dampen warming down; some speed it up. Two in the Arctic may speed it up quite a lot.
目前地球正在經(jīng)歷的全球變暖是由大氣中的某些氣體引起的，尤其是二氧化碳。這些氣體容許熱量以太陽光的形式透過大氣層，但阻擋其以波長更長的紅外線輻射到太空。這樣一來熱量就被留存在空氣中、水里和陸地上。二氧化碳增多就等于變暖加劇，這是個簡單的等式。只不過它其實并不簡單。一些反饋循環(huán)讓情況變得更復(fù)雜：有些抑制了變暖，有些則令其加速。北極的兩大反饋循環(huán)可能讓氣候變暖大幅加快。
One is that seawater is much darker than ice. It absorbs heat rather than reflecting it back into space. That melts more ice, which leaves more seawater exposed, which melts more ice. And so on. This helps explain why the Arctic is warming faster than the rest of the planet. The deal on climate change made in Paris in 2015 is meant to stop Earth’s surface temperature rising by more than 2°C above pre-industrial levels. In the unlikely event that it is fully implemented, winter temperatures over the Arctic ocean will still warm by between 5° and 9°C compared with their 1986-2005 average.
一是海水的顏色比冰深得多。海水吸收熱量而不是將其反射回太空。這會融化更多冰面，讓更多海水暴露出來，繼而融化更多的冰，如此循環(huán)。這可以解釋為什么北極比地球上其他地方變暖得更快。2015年在巴黎達成的氣候變化協(xié)議旨在將地球表面溫度較工業(yè)化前水平的升幅控制在2°C之內(nèi)。假使這一協(xié)議真的能完全落實，比起1986年至2005年的平均水平，北冰洋的冬季溫度仍會升高5°C 到 9°C。
The second feedback loop concerns not the water but the land. In the Arctic much of this is permafrost. That frozen soil locks up a lot of organic material. If the permafrost melts its organic contents can escape as a result of fire or decay, in the form of carbon dioxide or methane (which is a more potent greenhouse gas than CO2). This will speed up global warming directly—and the soot from the fires, when it settles on the ice, will darken it and thus speed its melting still more.
第二個反饋循環(huán)與水無關(guān)，而是有關(guān)陸地。北極的陸地表面大部分是永久凍土層，這些凍土鎖住了大量的有機物。如果永久凍土融化，其中的有機物便會因起火或腐爛而以二氧化碳或甲烷的形式逸出，而甲烷是一種比二氧化碳更強的溫室氣體。這將直接加速全球變暖，而且起火產(chǎn)生的煙灰一旦落在冰上就會染黑冰面，從而讓冰融化得更快。
Dead habitat walking
A warming Arctic could have malevolent effects. The world’s winds are driven in large part by the temperature difference between the poles and the tropics. If the Arctic heats faster than the tropics, this difference will decrease and wind speeds will slow—as they have done, in the northern hemisphere, by between 5 and 15% in the past 30 years. Less wind might sound desirable. It is not. One consequence is erratic behaviour of the northern jet stream, a circumpolar current, the oscillations of which sometimes bring cold air south and warm air north. More exaggerated oscillations would spell blizzards and heatwaves in unexpected places at unexpected times.
死寂棲息地復(fù)生
北極變暖可能會有極惡劣的后果。世界上的風(fēng)很大程度上是因兩極和熱帶地區(qū)的溫差而形成的。如果北極比熱帶地區(qū)升溫更快，這一溫差會減小，風(fēng)速就會減慢。這種情況已經(jīng)出現(xiàn)——過去30年來，北半球的風(fēng)速減緩了5%到15%。風(fēng)減少聽起來也許令人向往，實則不然。后果之一就是北半球的急流發(fā)生紊亂。急流是一種環(huán)極氣流，它的振蕩有時會將冷空氣帶到南方，或?qū)⑴諝鈳У奖狈?。如果急流振蕩幅度過大，可能會在意想不到的時間給意想不到的地方帶來暴風(fēng)雪和熱浪。
Ocean currents, too, may slow. The melting of Arctic ice dilutes salt water moving north from the tropics. That makes it less dense, and thus less inclined to sink for the return journey in the ocean depths. This slowing of circulation will tug at currents around the world, with effects on everything from the Indian monsoon to the pattern of El Niño in the Pacific ocean.
洋流也可能減緩。北極冰面融化，稀釋了從熱帶地區(qū)流向北方的海水。這導(dǎo)致海水密度降低，因而不易下沉至深海進行回流。這一循環(huán)放緩會拖慢全球的洋流，從印度的季風(fēng)到太平洋厄爾尼諾現(xiàn)象的規(guī)律，一切都會因此受到影響。
The scariest possibility of all is that something happens to the ice cap covering Greenland. This contains about 10% of the world’s fresh water. If bits of it melted, or just broke free to float in the water, sea levels could rise by a lot more than today’s projection of 74cm by the end of the century. At the moment, the risk of this happening is hard to assess because data are difficult to gather. But loss of ice from Greenland is accelerating.
在可能發(fā)生的情形中，最恐怖的是覆蓋格陵蘭島的冰蓋發(fā)生變化。格陵蘭島包含了全球約10%的淡水，如果這里的冰蓋融化一點，或者只是破裂后漂浮到海面上，那么到本世紀末海平面升高的水平將遠遠超過今天所預(yù)計的74厘米。目前很難評估這一情況發(fā)生的風(fēng)險，因為數(shù)據(jù)太難收集。但格陵蘭島冰蓋的融化正在加速。
What to do about all this is a different question. Even if the Paris agreement is stuck to scrupulously, the amount of carbon dioxide already in the atmosphere, together with that which will be added, looks bound eventually to make summer Arctic sea ice a thing of the past. Some talk of geoengineering—for example, spraying sulphates into the polar air to reflect sunlight back into space, or using salt to seed the creation of sunlight-blocking clouds. Such ideas would have unknown side-effects, but they are worth testing in pilot studies.
如何應(yīng)對這一切也是個問題。即便嚴格執(zhí)行了巴黎協(xié)定，大氣中已有的二氧化碳，再加上未來將會增加的，看起來最終仍會讓夏季的北冰洋海冰成為過去。有些人談到地球工程，比方說向極地大氣中噴灑硫酸鹽，從而將陽光反射回太空，或是撒鹽來促使水汽凝結(jié)成云，阻擋日光。這樣的想法可能會有未知的副作用，不過仍值得在試點研究中測試。
The hard truth, however, is that the Arctic as it is known today is almost certainly gone. Efforts to mitigate global warming by cutting emissions remain essential. But the state of the Arctic shows that humans cannot simply undo climate change. They will have to adapt to it.
然而一個鐵的事實是，幾乎可以肯定，我們今天所知道的北極已不復(fù)存在。通過減排來減緩全球變暖的努力仍然至關(guān)重要，但北極的情況表明，人類并不能簡單消除氣候變化的影響。他們必須去適應(yīng)這種變化。
