Terrestrial cooling in Northern Europe during the Eocene-Oligocene transition
Terrestrial cooling in Northern Europe during the Eocene-Oligocene transition
复制标题
DOI：
10.1073/pnas.1210930110
复制
发表时间：
2013-05-07
影响因子：
11.1
通讯作者：
Lohmann, Kyger C.
中科院分区：
文献类型：
--
作者：
Hren, Michael T.;Sheldon, Nathan D.;Lohmann, Kyger C.
地球化学和模拟研究表明，从始新世晚期的“温室”状态到渐新世34-33.5 Ma的“冰库”状态的转变是由大气中二氧化碳含量的减少触发的，这使得南极大陆上的永久冰盖迅速形成。海洋记录表明，在此期间，PCO(2)的下降伴随着高纬度海面和深海温度的显着下降，以及中高纬度地区季节性的增强。然而，这种气候转变的陆地记录显示了对PCO(2)和海洋温度变化的不同反应，一些记录表明温度对PCO下降的反应有明显的时间滞后。我们测量了英国汉普郡盆地Solent群淡水腹足类Viviparus lentus文石贝壳的Delta(47)，以重建始新世-渐新世过渡期间北大西洋地区的陆地温度和水文变化。我们的数据显示，在始新世-渐新世过渡期间，生长季地表水温下降(类似于10摄氏度)，对应于从始新世晚期到渐新世早期，年平均气温下降约4-6摄氏度。降温幅度类似于在这段时间内观测到的北大西洋海面温度的下降，并发生在主要的冰川扩张期间。这表明大气二氧化碳浓度、北半球温度和南极冰盖扩张之间存在密切联系。
Geochemical and modeling studies suggest that the transition from the "greenhouse" state of the Late Eocene to the "icehouse" conditions of the Oligocene 34-33.5 Ma was triggered by a reduction of atmospheric pCO(2) that enabled the rapid buildup of a permanent ice sheet on the Antarctic continent. Marine records show that the drop in pCO(2) during this interval was accompanied by a significant decline in high-latitude sea surface and deep ocean temperature and enhanced seasonality in middle and high latitudes. However, terrestrial records of this climate transition show heterogeneous responses to changing pCO(2) and ocean temperatures, with some records showing a significant time lag in the temperature response to declining pCO(2). We measured the Delta(47) of aragonite shells of the freshwater gastropod Viviparus lentus from the Solent Group, Hampshire Basin, United Kingdom, to reconstruct terrestrial temperature and hydrologic change in the North Atlantic region during the Eocene-Oligocene transition. Our data show a decrease in growing-season surface water temperatures (similar to 10 degrees C) during the Eocene-Oligocene transition, corresponding to an average decrease in mean annual air temperature of similar to 4-6 degrees C from the Late Eocene to Early Oligocene. The magnitude of cooling is similar to observed decreases in North Atlantic sea surface temperature over this interval and occurs during major glacial expansion. This suggests a close linkage between atmospheric carbon dioxide concentrations, Northern Hemisphere temperature, and expansion of the Antarctic ice sheets.