万物简史 第378期:进入对流层(19)

 　　What happens is that surface waters, as they get to the vicinity of Europe, 情况是这样的：表面海水抵达欧洲附近以后，

　　grow dense¹ and sink to great depths and begin a slow trip back to the southern hemisphere. 密度增加，沉到深处，慢慢返回南半球。

　　When they reach Antarctica, they are caught up in the Antarctic Circumpolar Current, where they are driven onward² into the Pacific. 这批海水抵达南极洲，遇上了南极绕极流，被往前推入了太平洋。

　　The process is very slow—it can take 1,500 years for water to travel from the North Atlantic to the mid-Pacific, 这个过程是很慢的——海水从北大西洋流到太平洋中部要花1500年时间，

　　but the volumes of heat and water they move are very considerable, and the influence on the climate is enormous. 但它运送的热量和水量是相当可观的，对气候的影响也是巨大的。

　　(As for the question of how anyone could possibly figure out how long it takes a drop of water to get from one ocean to another, （怎么有人可能计算出一滴水从一个大样到另一个大洋要花多长时间？

　　the answer is that scientists can measure compounds in the water like chlorofluorocarbons and work out how long it has been since they were last in the air. 关于这个问题，答案是：科学家们可以测定水里的混合物，比如含氯氟烃，从而计算出自它上次进入空气以来已有多长时间。

　　By comparing a lot of measurements from different depths and locations they can reasonably chart the water's movement.) 通过把不同深度、不同地点的测量结果进行比较，可以比较准确地绘制出水的运动路线图。）

　　Thermohaline circulation not only moves heat around, but also helps to stir up nutrients³ as the currents rise and fall, 热盐对流不仅传送热量，而且随着洋流的起伏，也起着搅动食物的作用，

　　making greater volumes of the ocean habitable for fish and other marine⁴ creatures. 使更大范围的海域适于鱼类和其他海洋动物生存。

　　Unfortunately, it appears the circulation may also be very sensitive to change. 不幸的是，热盐对流对周围的变化似乎也很敏感。

　　According to computer simulations, even a modest dilution⁵ of the ocean's salt content, 计算机模拟试验的结果表明，连海洋盐度稍有稀释，

　　from increased melting of the Greenland ice sheet, for instance—could disrupt the cycle disastrously⁶. 比如，由于格陵兰冰原的加快融化，也会灾难性地打乱这个循环。

　　The seas do one other great favor for us.  大海还帮了我们另一个大忙。

　　They soak up tremendous volumes of carbon and provide a means for it to be safely locked away. 它吸收大量的碳，并有办法把碳藏到安全的地方。

1 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

2 onward   

adj.向前的，前进的；adv.向前，前进，在先

参考例句：

• The Yellow River surges onward like ten thousand horses galloping.黄河以万马奔腾之势滚滚向前。
• He followed in the steps of forerunners and marched onward.他跟随着先辈的足迹前进。

3 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

4 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

5 dilution   

n.稀释，淡化

参考例句：

• There is no hard and fast rule about dilution.至于稀释程度，没有严格的规定。
• He attributed this to a dilution effect of the herbicide.他把这归因于除草剂的稀释效应。

6 disastrously   

ad.灾难性地

参考例句：

• Their profits began to spiral down disastrously. 他们的利润开始螺旋形地急剧下降。
• The fit between the country's information needs and its information media has become disastrously disjointed. 全国的信息需求与信息传播媒介之间的配置，出现了严重的不协调。