So when, in 2005, a paper in Nature reported, on the basis of the five pertinent shipborne surveys which had been made since 1957, a 30% drop in the volume of AMOC between 1992 and 2004, there was serious concern.

因此，2005 年，《自然》杂志的一篇论文根据自 1957 年以来进行的五次相关船载调查报告称， 1992 年至 2004 年间 AMOC 的数量下降了 30%， 引起了严重关注。