But their Numbers have dwindled since the dawn of the 20th century, with unknown consequences for ocean ecosystems and the planet's carbon cycle.

但自20世纪初以来，它们的数量已逐渐减少，随之而来的是由此对海洋生态系统和全球碳循环产生的未知后果。

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Since abandoning the dollar as a reserve implies radical change with unknown consequences, governments have been very reluctant to take the chance.

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