Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs
Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs
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DOI：
10.1038/35097000
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发表时间：
2001-10-04
期刊：
影响因子：
64.8
通讯作者：
Hall, MA
中科院分区：
文献类型：
--
作者：
Pearson, PN;Ditchfield, PW;Hall, MA
二氧化碳含量增加的气候模型预测，全球变暖会导致热带地区变暖，但基于古数据的古代气候调查通常表明，在假定的温室事件期间，热带地区的温度较低。例如，在晚白垩纪和始新世时期，有大量的地质证据表明温暖的，大部分是无冰的两极，但根据对生活在表面的浮游有孔虫壳的氧同位素古温学，热带海洋表面温度通常估计只有15-23度。在这里，我们对大多数此类数据的有效性提出质疑，理由是保存不良和成岩蚀变。我们提供了从不透水的富含粘土的沉积物中提取的保存异常完好的有孔虫壳的新数据，这些数据表明，在研究的区间内，热带海洋表面温度至少为28-32度。这些温暖的温度更符合我们对温度敏感的化石生物的地理分布的理解，以及二氧化碳水平增加的气候模型的结果。
Climate models with increased levels of carbon dioxide predict that global warming causes heating in the tropics, but investigations of ancient climates based on palaeodata have generally indicated cool tropical temperatures during supposed greenhouse episodes. For example, in the Late Cretaceous and Eocene epochs there is abundant geological evidence for warm, mostly ice-free poles, but tropical sea surface temperatures are generally estimated to be only 15-23 degreesC, based on oxygen isotope palaeothermometry of surface-dwelling planktonic foraminifer shells. Here we question the validity of most such data on the grounds of poor preservation and diagenetic alteration. We present new data from exceptionally well preserved foraminifer shells extracted from impermeable clay-rich sediments, which indicate that for the intervals studied, tropical sea surface temperatures were at least 28-32 degreesC. These warm temperatures are more in line with our understanding of the geographical distributions of temperature-sensitive fossil organisms and the results of climate models with increased CO2 levels.