The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons
<p>The Eocene–Oligocene transition (EOT) was a climate shift from a largely ice-free greenhouse world to an icehouse climate, involving the first major glaciation of Antarctica and global cooling occurring <span class="inline-formula">∼34</span> million years ago (Ma) and...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-01-01
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| Series: | Climate of the Past |
| Online Access: | https://cp.copernicus.org/articles/17/269/2021/cp-17-269-2021.pdf |
| _version_ | 1818734704887595008 |
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| author | D. K. Hutchinson H. K. Coxall D. J. Lunt M. Steinthorsdottir M. Steinthorsdottir A. M. de Boer M. Baatsen A. von der Heydt A. von der Heydt M. Huber A. T. Kennedy-Asser L. Kunzmann J.-B. Ladant C. H. Lear K. Moraweck P. N. Pearson E. Piga M. J. Pound U. Salzmann H. D. Scher W. P. Sijp K. K. Śliwińska P. A. Wilson Z. Zhang Z. Zhang |
| author_facet | D. K. Hutchinson H. K. Coxall D. J. Lunt M. Steinthorsdottir M. Steinthorsdottir A. M. de Boer M. Baatsen A. von der Heydt A. von der Heydt M. Huber A. T. Kennedy-Asser L. Kunzmann J.-B. Ladant C. H. Lear K. Moraweck P. N. Pearson E. Piga M. J. Pound U. Salzmann H. D. Scher W. P. Sijp K. K. Śliwińska P. A. Wilson Z. Zhang Z. Zhang |
| author_sort | D. K. Hutchinson |
| collection | DOAJ |
| description | <p>The Eocene–Oligocene transition (EOT) was a climate shift from a largely ice-free greenhouse world
to an icehouse climate, involving the first major glaciation of Antarctica and global cooling
occurring <span class="inline-formula">∼34</span> million years ago (Ma) and lasting <span class="inline-formula">∼790</span> <span class="inline-formula">kyr</span>. The change is
marked by a global shift in deep-sea <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> representing a combination of
deep-ocean cooling and growth in land ice volume. At the same time, multiple independent proxies
for ocean temperature indicate sea surface cooling, and major changes in global fauna and flora
record a shift toward more cold-climate-adapted species. The two principal suggested explanations
of this transition are a decline in atmospheric <span class="inline-formula">CO<sub>2</sub></span> and changes to ocean gateways,
while orbital forcing likely influenced the precise timing of the glaciation. Here we review and
synthesise proxy evidence of palaeogeography, temperature, ice sheets, ocean circulation and
<span class="inline-formula">CO<sub>2</sub></span> change from the marine and terrestrial realms. Furthermore, we quantitatively
compare proxy records of change to an ensemble of climate model simulations of temperature change
across the EOT. The simulations compare three forcing mechanisms across the EOT: <span class="inline-formula">CO<sub>2</sub></span>
decrease, palaeogeographic changes and ice sheet growth. Our model ensemble results demonstrate
the need for a global cooling mechanism beyond the imposition of an ice sheet or palaeogeographic
changes. We find that <span class="inline-formula">CO<sub>2</sub></span> forcing involving a large decrease in <span class="inline-formula">CO<sub>2</sub></span> of
ca. 40 % (<span class="inline-formula">∼325</span> <span class="inline-formula">ppm</span> drop) provides the best fit to the available proxy evidence,
with ice sheet and palaeogeographic changes playing a secondary role. While this large decrease is
consistent with some <span class="inline-formula">CO<sub>2</sub></span> proxy records (the extreme endmember of<span id="page270"/> decrease), the
positive feedback mechanisms on ice growth are so strong that a modest <span class="inline-formula">CO<sub>2</sub></span> decrease
beyond a critical threshold for ice sheet initiation is well capable of triggering rapid ice sheet
growth. Thus, the amplitude of <span class="inline-formula">CO<sub>2</sub></span> decrease signalled by our data–model comparison
should be considered an upper estimate and perhaps artificially large, not least because the
current generation of climate models do not include dynamic ice sheets and in some cases may be
under-sensitive to <span class="inline-formula">CO<sub>2</sub></span> forcing. The model ensemble also cannot exclude the possibility
that palaeogeographic changes could have triggered a reduction in <span class="inline-formula">CO<sub>2</sub></span>.</p> |
| first_indexed | 2024-12-18T00:09:36Z |
| format | Article |
| id | doaj.art-7b4ca81a6eb84d0a8275a4fd2dba06c9 |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-18T00:09:36Z |
| publishDate | 2021-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-7b4ca81a6eb84d0a8275a4fd2dba06c92022-12-21T21:27:43ZengCopernicus PublicationsClimate of the Past1814-93241814-93322021-01-011726931510.5194/cp-17-269-2021The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisonsD. K. Hutchinson0H. K. Coxall1D. J. Lunt2M. Steinthorsdottir3M. Steinthorsdottir4A. M. de Boer5M. Baatsen6A. von der Heydt7A. von der Heydt8M. Huber9A. T. Kennedy-Asser10L. Kunzmann11J.-B. Ladant12C. H. Lear13K. Moraweck14P. N. Pearson15E. Piga16M. J. Pound17U. Salzmann18H. D. Scher19W. P. Sijp20K. K. Śliwińska21P. A. Wilson22Z. Zhang23Z. Zhang24Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, SwedenSchool of Geographical Sciences, University of Bristol, Bristol, UKDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, SwedenDepartment of Palaeobiology, Swedish Museum of Natural History, Stockholm, SwedenDepartment of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, SwedenInstitute for Marine and Atmospheric Research, Department of Physics, Utrecht University, Utrecht, the NetherlandsInstitute for Marine and Atmospheric Research, Department of Physics, Utrecht University, Utrecht, the NetherlandsCentre for Complex Systems Studies, Utrecht University, Utrecht, the NetherlandsDepartment of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, USASchool of Geographical Sciences, University of Bristol, Bristol, UKSenckenberg Natural History Collections, Dresden, GermanyDepartment of Earth and Environmental Sciences, University of Michigan, Ann Arbor, USASchool of Earth and Ocean Sciences, Cardiff University, Cardiff, UKSenckenberg Natural History Collections, Dresden, GermanySchool of Earth and Ocean Sciences, Cardiff University, Cardiff, UKSchool of Earth and Ocean Sciences, Cardiff University, Cardiff, UKDepartment of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UKDepartment of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UKSchool of the Earth, Ocean and Environment, University of South Carolina, Columbia SC, USAClimate Change Research Centre, University of New South Wales, Sydney, AustraliaDepartment of Stratigraphy, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, DenmarkUniversity of Southampton, National Oceanography Centre, Southampton, UKDepartment of Atmospheric Science, China University of Geoscience, Wuhan, ChinaNORCE Research and Bjerknes Centre for Climate Research, Bergen, Norway<p>The Eocene–Oligocene transition (EOT) was a climate shift from a largely ice-free greenhouse world to an icehouse climate, involving the first major glaciation of Antarctica and global cooling occurring <span class="inline-formula">∼34</span> million years ago (Ma) and lasting <span class="inline-formula">∼790</span> <span class="inline-formula">kyr</span>. The change is marked by a global shift in deep-sea <span class="inline-formula"><i>δ</i><sup>18</sup>O</span> representing a combination of deep-ocean cooling and growth in land ice volume. At the same time, multiple independent proxies for ocean temperature indicate sea surface cooling, and major changes in global fauna and flora record a shift toward more cold-climate-adapted species. The two principal suggested explanations of this transition are a decline in atmospheric <span class="inline-formula">CO<sub>2</sub></span> and changes to ocean gateways, while orbital forcing likely influenced the precise timing of the glaciation. Here we review and synthesise proxy evidence of palaeogeography, temperature, ice sheets, ocean circulation and <span class="inline-formula">CO<sub>2</sub></span> change from the marine and terrestrial realms. Furthermore, we quantitatively compare proxy records of change to an ensemble of climate model simulations of temperature change across the EOT. The simulations compare three forcing mechanisms across the EOT: <span class="inline-formula">CO<sub>2</sub></span> decrease, palaeogeographic changes and ice sheet growth. Our model ensemble results demonstrate the need for a global cooling mechanism beyond the imposition of an ice sheet or palaeogeographic changes. We find that <span class="inline-formula">CO<sub>2</sub></span> forcing involving a large decrease in <span class="inline-formula">CO<sub>2</sub></span> of ca. 40 % (<span class="inline-formula">∼325</span> <span class="inline-formula">ppm</span> drop) provides the best fit to the available proxy evidence, with ice sheet and palaeogeographic changes playing a secondary role. While this large decrease is consistent with some <span class="inline-formula">CO<sub>2</sub></span> proxy records (the extreme endmember of<span id="page270"/> decrease), the positive feedback mechanisms on ice growth are so strong that a modest <span class="inline-formula">CO<sub>2</sub></span> decrease beyond a critical threshold for ice sheet initiation is well capable of triggering rapid ice sheet growth. Thus, the amplitude of <span class="inline-formula">CO<sub>2</sub></span> decrease signalled by our data–model comparison should be considered an upper estimate and perhaps artificially large, not least because the current generation of climate models do not include dynamic ice sheets and in some cases may be under-sensitive to <span class="inline-formula">CO<sub>2</sub></span> forcing. The model ensemble also cannot exclude the possibility that palaeogeographic changes could have triggered a reduction in <span class="inline-formula">CO<sub>2</sub></span>.</p>https://cp.copernicus.org/articles/17/269/2021/cp-17-269-2021.pdf |
| spellingShingle | D. K. Hutchinson H. K. Coxall D. J. Lunt M. Steinthorsdottir M. Steinthorsdottir A. M. de Boer M. Baatsen A. von der Heydt A. von der Heydt M. Huber A. T. Kennedy-Asser L. Kunzmann J.-B. Ladant C. H. Lear K. Moraweck P. N. Pearson E. Piga M. J. Pound U. Salzmann H. D. Scher W. P. Sijp K. K. Śliwińska P. A. Wilson Z. Zhang Z. Zhang The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons Climate of the Past |
| title | The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons |
| title_full | The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons |
| title_fullStr | The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons |
| title_full_unstemmed | The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons |
| title_short | The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons |
| title_sort | eocene oligocene transition a review of marine and terrestrial proxy data models and model data comparisons |
| url | https://cp.copernicus.org/articles/17/269/2021/cp-17-269-2021.pdf |
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