我建议你阅读原始论文[李尔et al . (2000)] [1]。他们解释,结果当地极地和与极地表面温度有关。表面温度将相当大的不同取决于接近深水区域形成。随着这些领域相当的地方,相对较小的变化形成的位置会导致深水温度被修改。>温度记录显示了过去50我一般的降温趋势,但其分辨率太低定义突然极端温度。假设深水形成过程中高纬度地区盛行在过去50我,可以推断出这些深海温度代表极性表面温度(1)温度趋势(图1 c)似乎包含四个主要的冷却阶段隔开一段更加稳定的温度。这些冷却阶段发生在中始新世早期,始新世末至早渐新世,晚中新世中期,Plio-Pleistocene。>选择证据支持这些主要的存在冷却阶段。中始新世早期急剧冷却被调用来解释大量的硅质沉积物的年龄(20)。始新世早期气候温暖被认为促进了硅质岩石的,紧张的化学风化作用在高纬度地区,导致高浓度的溶解二氧化硅在海洋中。 The subsequent cooling stimulated upwelling of nutrient-rich water and intense biosilicification. The cooling over the Late Eocene through Ear- ly Oligocene is coincident with the transition from “Paleogene” to “transitional” benthic foraminiferal faunas and high extinction rates in planktonic and terrestrial faunas. The initiation of this deep water cooling also coincides with a reduction in the extent of tropical rainforests on land (21, 22). The cooling in the late Middle Miocene is marked by a narrowing of tropical and warm subtropical biotic provinces in terrestrial and marine environments (23). Warmwater diatom assemblages were replaced by cold-water species at this time (24). The Plio-Pleistocene cooling is not represented by an extinction phase in benthic foraminiferal faunas; instead, faunal groups adapted to the changing bottom water conditions by migration (21). When you use data from other regions, you get a much different result. For instance, [Elderfield & Ganssen (2000)][2] showed how different the temperature changes can be for different species and locations. [![Elderfield Nature paper][3]][3] [1]: http://users.clas.ufl.edu/eemartin/GLY6075F08/LearetalScience'00.pdf [2]: ftp://wserv2.esc.cam.ac.uk/pub/harrye/Reprints%20of%20Elderfield%20Publications/2000/2000_Elderfield_Ganssen.pdf [3]: http://i.stack.imgur.com/4wIa8.gif