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Causes of ice age intensification across the Mid-Pleistocene Transition
During the Mid-Pleistocene Transition (MPT; 1,200–800 kya), Earth’s orbitally paced ice age cycles intensified, lengthened from ∼40,000 (∼40 ky) to ∼100 ky, and became distinctly asymmetrical. Testing hypotheses that implicate changing atmospheric CO(2) levels as a driver of the MPT has proven diffi...
Autores principales: | , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
National Academy of Sciences
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740680/ https://www.ncbi.nlm.nih.gov/pubmed/29180424 http://dx.doi.org/10.1073/pnas.1702143114 |
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author | Chalk, Thomas B. Hain, Mathis P. Foster, Gavin L. Rohling, Eelco J. Sexton, Philip F. Badger, Marcus P. S. Cherry, Soraya G. Hasenfratz, Adam P. Haug, Gerald H. Jaccard, Samuel L. Martínez-García, Alfredo Pälike, Heiko Pancost, Richard D. Wilson, Paul A. |
author_facet | Chalk, Thomas B. Hain, Mathis P. Foster, Gavin L. Rohling, Eelco J. Sexton, Philip F. Badger, Marcus P. S. Cherry, Soraya G. Hasenfratz, Adam P. Haug, Gerald H. Jaccard, Samuel L. Martínez-García, Alfredo Pälike, Heiko Pancost, Richard D. Wilson, Paul A. |
author_sort | Chalk, Thomas B. |
collection | PubMed |
description | During the Mid-Pleistocene Transition (MPT; 1,200–800 kya), Earth’s orbitally paced ice age cycles intensified, lengthened from ∼40,000 (∼40 ky) to ∼100 ky, and became distinctly asymmetrical. Testing hypotheses that implicate changing atmospheric CO(2) levels as a driver of the MPT has proven difficult with available observations. Here, we use orbitally resolved, boron isotope CO(2) data to show that the glacial to interglacial CO(2) difference increased from ∼43 to ∼75 μatm across the MPT, mainly because of lower glacial CO(2) levels. Through carbon cycle modeling, we attribute this decline primarily to the initiation of substantive dust-borne iron fertilization of the Southern Ocean during peak glacial stages. We also observe a twofold steepening of the relationship between sea level and CO(2)-related climate forcing that is suggestive of a change in the dynamics that govern ice sheet stability, such as that expected from the removal of subglacial regolith or interhemispheric ice sheet phase-locking. We argue that neither ice sheet dynamics nor CO(2) change in isolation can explain the MPT. Instead, we infer that the MPT was initiated by a change in ice sheet dynamics and that longer and deeper post-MPT ice ages were sustained by carbon cycle feedbacks related to dust fertilization of the Southern Ocean as a consequence of larger ice sheets. |
format | Online Article Text |
id | pubmed-5740680 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | National Academy of Sciences |
record_format | MEDLINE/PubMed |
spelling | pubmed-57406802018-01-22 Causes of ice age intensification across the Mid-Pleistocene Transition Chalk, Thomas B. Hain, Mathis P. Foster, Gavin L. Rohling, Eelco J. Sexton, Philip F. Badger, Marcus P. S. Cherry, Soraya G. Hasenfratz, Adam P. Haug, Gerald H. Jaccard, Samuel L. Martínez-García, Alfredo Pälike, Heiko Pancost, Richard D. Wilson, Paul A. Proc Natl Acad Sci U S A Physical Sciences During the Mid-Pleistocene Transition (MPT; 1,200–800 kya), Earth’s orbitally paced ice age cycles intensified, lengthened from ∼40,000 (∼40 ky) to ∼100 ky, and became distinctly asymmetrical. Testing hypotheses that implicate changing atmospheric CO(2) levels as a driver of the MPT has proven difficult with available observations. Here, we use orbitally resolved, boron isotope CO(2) data to show that the glacial to interglacial CO(2) difference increased from ∼43 to ∼75 μatm across the MPT, mainly because of lower glacial CO(2) levels. Through carbon cycle modeling, we attribute this decline primarily to the initiation of substantive dust-borne iron fertilization of the Southern Ocean during peak glacial stages. We also observe a twofold steepening of the relationship between sea level and CO(2)-related climate forcing that is suggestive of a change in the dynamics that govern ice sheet stability, such as that expected from the removal of subglacial regolith or interhemispheric ice sheet phase-locking. We argue that neither ice sheet dynamics nor CO(2) change in isolation can explain the MPT. Instead, we infer that the MPT was initiated by a change in ice sheet dynamics and that longer and deeper post-MPT ice ages were sustained by carbon cycle feedbacks related to dust fertilization of the Southern Ocean as a consequence of larger ice sheets. National Academy of Sciences 2017-12-12 2017-11-27 /pmc/articles/PMC5740680/ /pubmed/29180424 http://dx.doi.org/10.1073/pnas.1702143114 Text en Copyright © 2017 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/ This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) . |
spellingShingle | Physical Sciences Chalk, Thomas B. Hain, Mathis P. Foster, Gavin L. Rohling, Eelco J. Sexton, Philip F. Badger, Marcus P. S. Cherry, Soraya G. Hasenfratz, Adam P. Haug, Gerald H. Jaccard, Samuel L. Martínez-García, Alfredo Pälike, Heiko Pancost, Richard D. Wilson, Paul A. Causes of ice age intensification across the Mid-Pleistocene Transition |
title | Causes of ice age intensification across the Mid-Pleistocene Transition |
title_full | Causes of ice age intensification across the Mid-Pleistocene Transition |
title_fullStr | Causes of ice age intensification across the Mid-Pleistocene Transition |
title_full_unstemmed | Causes of ice age intensification across the Mid-Pleistocene Transition |
title_short | Causes of ice age intensification across the Mid-Pleistocene Transition |
title_sort | causes of ice age intensification across the mid-pleistocene transition |
topic | Physical Sciences |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740680/ https://www.ncbi.nlm.nih.gov/pubmed/29180424 http://dx.doi.org/10.1073/pnas.1702143114 |
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