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Deep heat: proxies, miocene ice, and an end in sight for paleoclimate paradoxes?

Deep heat: proxies, miocene ice, and an end in sight for paleoclimate paradoxes?
Deep heat: proxies, miocene ice, and an end in sight for paleoclimate paradoxes?
The mid Miocene represents an important target for paleoclimatic study because the atmospheric CO2 concentration ranged from near modern values to ∼800 ppm, while a large, dynamic Antarctic ice sheet was likely to have been present throughout much of this interval. In this special issue, Modestou et al. (2020) (doi.org/10.1029/2020PA003927) reconstruct deep ocean warmth based on the clumped isotopic composition of benthic foraminifera, a technique that allows the ice volume and thermal components of the benthic oxygen isotope stack to be separated. These data reveal a very warm deep ocean while simultaneously suggesting that continental ice volume may, at times, have been greater than today. Here, I review these results in the context of recent developments in geochemical proxies and ice sheet modeling, and explore how the presence of a large Miocene ice sheet could be reconciled with CO2 at least as high as present. More broadly, I argue that many of the 'paradoxes' that pepper the paleoclimate literature result as much from our imperfect understanding of the proxies, as from our understanding of the climate system. Robust proxies with a well-understood mechanistic basis, as employed by Modestou et al. (2020), as well as advances in model-data comparability usher in a new era of palaeoclimate research; an exciting future of untangling Earth's myriad past climate states awaits.
2572-4525
Evans, David
878c65c7-eab9-4362-896b-166e165eb94b
Evans, David
878c65c7-eab9-4362-896b-166e165eb94b

Evans, David (2021) Deep heat: proxies, miocene ice, and an end in sight for paleoclimate paradoxes? Paleoceanography and Paleoclimatology, 36 (3), [e2020PA004174]. (doi:10.1029/2020PA004174).

Record type: Article

Abstract

The mid Miocene represents an important target for paleoclimatic study because the atmospheric CO2 concentration ranged from near modern values to ∼800 ppm, while a large, dynamic Antarctic ice sheet was likely to have been present throughout much of this interval. In this special issue, Modestou et al. (2020) (doi.org/10.1029/2020PA003927) reconstruct deep ocean warmth based on the clumped isotopic composition of benthic foraminifera, a technique that allows the ice volume and thermal components of the benthic oxygen isotope stack to be separated. These data reveal a very warm deep ocean while simultaneously suggesting that continental ice volume may, at times, have been greater than today. Here, I review these results in the context of recent developments in geochemical proxies and ice sheet modeling, and explore how the presence of a large Miocene ice sheet could be reconciled with CO2 at least as high as present. More broadly, I argue that many of the 'paradoxes' that pepper the paleoclimate literature result as much from our imperfect understanding of the proxies, as from our understanding of the climate system. Robust proxies with a well-understood mechanistic basis, as employed by Modestou et al. (2020), as well as advances in model-data comparability usher in a new era of palaeoclimate research; an exciting future of untangling Earth's myriad past climate states awaits.

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Published date: 2 February 2021

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Local EPrints ID: 502468
URI: http://eprints.soton.ac.uk/id/eprint/502468
ISSN: 2572-4525
PURE UUID: 3417c59d-04e5-4211-af10-2e09278c1b6d
ORCID for David Evans: ORCID iD orcid.org/0000-0002-8685-671X

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Date deposited: 26 Jun 2025 17:08
Last modified: 28 Jun 2025 04:05

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Author: David Evans ORCID iD

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