Boron based insights into Plio-Pleistocene carbon cycle changes and global climate evolution
From the Pliocene to the modern, the Earth’s climate has undergone a vast and significant change from a world dominated by continental ice restricted only to Antarctica with a rhythmic 41 kyr beat, through a period of declining atmospheric CO2 and cooling culminating with the bihemispheric glaciatio...
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| Format: | Thesis |
| Language: | English |
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2014
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| Online Access: | https://eprints.soton.ac.uk/374239/ https://eprints.soton.ac.uk/374239/1/Chalk%252C%2520Tom_PhD_Thesis_Dec_14.pdf |
| Summary: | From the Pliocene to the modern, the Earth’s climate has undergone a vast and significant change from a world dominated by continental ice restricted only to Antarctica with a rhythmic 41 kyr beat, through a period of declining atmospheric CO2 and cooling culminating with the bihemispheric glaciation known today, dominated by 100 kyr cyclicity. Ocean circulation is often given a central role in the dynamics of the late Neogene although many questions, such as the role of the North Atlantic in glacial-interglacial CO2 change remain. It is a well-studied region however and as such provides an ideal location for further study with novel proxies that may potentially provide new insights. Similarly, atmospheric CO2 is often thought to be the most crucial single variable driving Plio-Pleistocene climate change. Atmospheric CO2 reconstructions so far published beyond the end of the 800 ka Dome C ice core record are however few and of relatively low resolution and/or precision. This is at present hampering our understanding of CO2-climate interaction for climates warmer than the present and must be addressed as a priority given humanity’s ever-increasing CO2 emissions and anthropogenic global warming. This thesis aims to address these issues using boron-based proxies in foraminiferal carbonate. The potential power of these boron based proxies to directly quantify the marine carbonate system in the past has an enormous draw, both as a pH-CO2 proxy, but also for identifying the role of the deep ocean circulation changes in ocean carbon storage and release on orbital timescales. The first half of this thesis aims to better address the role of ocean circulation in rapid climate change and carbon storage over glacial-interglacial cycles. ?11B and B/Ca records from benthic foraminifera (Cibicidoides wuellerstorfi) from three cores in the North Atlantic spanning the last full glacial cycle and making up a depth, latitude and longitude transect are presented. These show that over this period, North Atlantic circulation is both ... |
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