Sea level and deep-sea temperature reconstructions suggest quasi-stable states and critical transitions over the past 40 million years
Sea level and deep-sea temperature variations are key indicators of global climate changes. For continuous records over millions of years, deep-sea carbonate microfossil-based 18O (c) records are indispensable because they reflect changes in both deep-sea temperature and seawater 18O (w); the latter...
| Published in: | Science Advances |
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| Main Authors: | , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://eprints.soton.ac.uk/490646/ https://eprints.soton.ac.uk/490646/1/sciadv.abf5326.pdf |
| Summary: | Sea level and deep-sea temperature variations are key indicators of global climate changes. For continuous records over millions of years, deep-sea carbonate microfossil-based 18O (c) records are indispensable because they reflect changes in both deep-sea temperature and seawater 18O (w); the latter are related to ice volume and, thus, to sea level changes. Deep-sea temperature is usually resolved using elemental ratios in the same benthic microfossil shells used for c, with linear scaling of residual w to sea level changes. Uncertainties are large and the linear-scaling assumption remains untested. Here, we present a new process-based approach to assess relationships between changes in sea level, mean ice sheet 18O, and both deep-sea w and temperature and find distinct nonlinearity between sea level and w changes. Application to c records over the past 40 million years suggests that Earth's climate system has complex dynamical behavior, with threshold-like adjustments (critical transitions) that separate quasi-stable deep-sea temperature and ice-volume states. |
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