在此之前，在世界大多数地区，人们没有持续、长期的自然现象记录，占地球三分之二的洋面更是一片空白。

Before that, most parts of the world did not keep consistent, long-term records of natural events, and the oceans, two-thirds of the globe, were largely deserted.

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系统而详实了解覆盖地球表面三分之二的海洋水域的化学特性、地形及水流特性代价高昂，但是可以实现的。

Systematic and detailed understanding of the chemistry, topography and flow of the waters that cover two-thirds of the planet would be costly, but it could be achieved.

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美国地质调查局2007年进行的一项研究发现：如果北极地区的冰层持续融化，那么地球上三分之二的北极熊在本世纪中叶前就可能消失。

A 2007 study by the U.S. Geological Survey found that two-thirds of the polar bears on the planet could disappear by mid-century if Arctic ice keeps melting.

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