Lawrence Kira T, Liu Zhonghui, Herbert Timothy D
Department of Geological Sciences, Brown University, Box 1846, Providence, RI 02912, USA.
Science. 2006 Apr 7;312(5770):79-83. doi: 10.1126/science.1120395.
A tropical Pacific climate state resembling that of a permanent El Niño is hypothesized to have ended as a result of a reorganization of the ocean heat budget approximately 3 million years ago, a time when large ice sheets appeared in the high latitudes of the Northern Hemisphere. We report a high-resolution alkenone reconstruction of conditions in the heart of the eastern equatorial Pacific (EEP) cold tongue that reflects the combined influences of changes in the equatorial thermocline, the properties of the thermocline's source waters, atmospheric greenhouse gas content, and orbital variations on sea surface temperature (SST) and biological productivity over the past 5 million years. Our data indicate that the intensification of Northern Hemisphere glaciation approximately 3 million years ago did not interrupt an almost monotonic cooling of the EEP during the Plio-Pleistocene. SST and productivity in the eastern tropical Pacific varied in phase with global ice volume changes at a dominant 41,000-year (obliquity) frequency throughout this time. Changes in the Southern Hemisphere most likely modulated most of the changes observed.
一种类似于永久性厄尔尼诺现象的热带太平洋气候状态被假定在大约300万年前由于海洋热量收支的重新调整而结束，当时北半球高纬度地区出现了大型冰盖。我们报告了对赤道东太平洋（EEP）冷舌中心区域状况的高分辨率烯酮重建结果，该结果反映了过去500万年中赤道温跃层变化、温跃层源水特性、大气温室气体含量以及轨道变化对海面温度（SST）和生物生产力的综合影响。我们的数据表明，大约300万年前北半球冰川作用的加剧并没有打断上新世 - 更新世期间EEP几乎单调的变冷过程。在此期间，热带东太平洋的SST和生产力与全球冰量变化在占主导的41000年（倾角）频率上呈同相位变化。南半球的变化很可能调节了所观察到的大部分变化。
