这一洋流有时被称作为北大西洋传送器。



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Atlantic
Mississippi River

选材／校对／翻译：hqj5715
Is Earth's climate vulnerable to small disturbances? Two geologists writing in Scientific American described the past vulnerability of an ocean current sometimes called the North Atlantic conveyor. The conveyor works like this. At about 2,000 feet beneath the surface of the Atlantic Ocean extra-salty water flows northward from the tropics. Winds over the North Atlantic sweep surface water aside, allowing this warm salty water to rise to the surface and come into contact with the cold air. Heat passes from the water to the air. The extra-salty water, now extra-dense because it is only a few degrees above freezing, sinks to near the bottom of the Atlantic and flows southward around Africa. Meanwhile, the warmed air passes over Europe and makes European winters warmer than they would be otherwise. During a one-thousand-year period about 11,000 years ago, this conveyor was shut down, because the North Atlantic was flooded with melt water from Canadian glaciers. Previously, that melt water had flowed down the Mississippi River. But at some point the retreat of the glaciers opened a channel to the east.
地球的气候是否倾向于小的不稳定？两位地质学家在科学美国人上描述了一洋流过去的不稳定性，这一洋流有时被称作为北大西洋传送器。 这一传送装置的工作原理是这样的。在大西洋表面大约2000尺左右有一股咸度较高的水流从回归线向北流动。北大西洋上的海风将表面的海水吹向一边，以使这一温暖的咸度较高的海水上升到海面并与较冷的空气接触。 热量从海水传到空气中。咸度较高的海水，现在因为温度只在冰点以上几度而变的密度非常高，下沉到大西洋的底部，洋流在非洲附近向南流动。于此同时，温暖的空气经过欧洲使得欧洲的冬天比应该的要暖的多。 在过去的1000年到大约11000之间，这一传送带处于关闭状态，因为北大西洋注满了从加拿大冰川融化的水。以前，这些融化的水是应该流入密西西比河的。但是在一些情况下融化的冰川开通了往东的河道。