Warm upwelling regions in the Pliocene warm period
Warm upwelling regions in the Pliocene warm period
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DOI：
10.1029/2006pa001394
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发表时间：
2007-08-10
期刊：
影响因子：
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通讯作者：
McCarthy, Matthew D.
中科院分区：
文献类型：
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作者：
Dekens, Petra S.;Ravelo, Ana Christina;McCarthy, Matthew D.
鉴于上升流过程对沿海生产力和区域气候的重要性，研究上升流区域在全球气候变化背景下的作用至关重要。我们在三个重要的上升流地区产生了过去500万年的海表面温度(SST)记录：赤道东太平洋、加利福尼亚州边缘和秘鲁边缘。在类似于3.0 Ma之前，所有地点的海温都明显高于今天(高出3-9摄氏度)，这表明在上新世早期(4.6至3.1 Ma)，即地球最近的全球持续变暖时期，不存在具有现代太平洋特征的冷上升流区域。烯酮、磷和有机碳的质量积累速率记录表明，生产力和海温的变化是解耦的，即使在上新世早期海温变暖的情况下，也出现了富营养水的上升流。因此，SST的长期趋势可能是由上升水温度的变化解释的，而不仅仅是上升有利风的强度。上升区的逐渐冷却在北半球显著的冰川开始之前就开始了，这一事实进一步证明，冰盖的增长及其对大气风的影响不能单独解释上升区的冷却。我们的结果表明，上升流区的长期平均海温受通风温跃层深度和/或温度的全球变化的影响。
Given the importance of upwelling processes to coastal productivity and regional climate, it is critical to study the role of upwelling regions within the context of global climate change. We generated sea surface temperature (SST) records for the last 5 million years in three important upwelling regions: the eastern equatorial Pacific, the California margin, and the Peru margin. Prior to similar to 3.0 Ma, SSTs at all sites were significantly warmer than today (by 3-9 degrees C), indicating that cold upwelling regions that characterize the modern Pacific Ocean did not exist in the early Pliocene warm period (4.6 to 3.1 Ma), Earth's most recent period of sustained global warmth. Alkenone, phosphorus, and organic carbon mass accumulation rate records indicate that changes in productivity and SST were decoupled and that upwelling of nutrient enriched water occurred even when SSTs were warm during the early Pliocene. Thus the long-term trends in SST are likely explained by changes in the temperature of upwelled water rather than in the strength of upwelling-favorable winds alone. The fact that gradual cooling of upwelling regions began before the onset of significant Northern Hemisphere glaciation provides further evidence that the growth of ice sheets and their influence on atmospheric winds alone can not explain the cooling of upwelling regions. Our results suggest that the long-term average SSTs of upwelling regions are influenced by global changes in the depth and/or temperature of the ventilated thermocline.