Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels
Atmospheric pCO2 is a critical component of the global carbon system and is considered to be the major control of Earth's past, present, and future climate. Accurate and precise reconstructions of its concentration through geological time are therefore crucial to our understanding of the Earth...
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fttriple:oai:gotriple.eu:oai:doaj.org/article:05f1c31f9be14e5fadebfcb7cb3466bb 2023-05-15T16:38:56+02:00 Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels M. P. S. Badger T. B. Chalk G. L. Foster P. R. Bown S. J. Gibbs P. F. Sexton D. N. Schmidt H. Pälike A. Mackensen R. D. Pancost 2019-03-01 https://doi.org/10.5194/cp-15-539-2019 https://www.clim-past.net/15/539/2019/cp-15-539-2019.pdf https://doaj.org/article/05f1c31f9be14e5fadebfcb7cb3466bb en eng Copernicus Publications doi:10.5194/cp-15-539-2019 1814-9324 1814-9332 https://www.clim-past.net/15/539/2019/cp-15-539-2019.pdf https://doaj.org/article/05f1c31f9be14e5fadebfcb7cb3466bb undefined Climate of the Past, Vol 15, Pp 539-554 (2019) envir geo Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2019 fttriple https://doi.org/10.5194/cp-15-539-2019 2023-01-22T17:50:37Z Atmospheric pCO2 is a critical component of the global carbon system and is considered to be the major control of Earth's past, present, and future climate. Accurate and precise reconstructions of its concentration through geological time are therefore crucial to our understanding of the Earth system. Ice core records document pCO2 for the past 800 kyr, but at no point during this interval were CO2 levels higher than today. Interpretation of older pCO2 has been hampered by discrepancies during some time intervals between two of the main ocean-based proxy methods used to reconstruct pCO2: the carbon isotope fractionation that occurs during photosynthesis as recorded by haptophyte biomarkers (alkenones) and the boron isotope composition (δ11B) of foraminifer shells. Here, we present alkenone and δ11B-based pCO2 reconstructions generated from the same samples from the Pliocene and across a Pleistocene glacial–interglacial cycle at Ocean Drilling Program (ODP) Site 999. We find a muted response to pCO2 in the alkenone record compared to contemporaneous ice core and δ11B records, suggesting caution in the interpretation of alkenone-based records at low pCO2 levels. This is possibly caused by the physiology of CO2 uptake in the haptophytes. Our new understanding resolves some of the inconsistencies between the proxies and highlights that caution may be required when interpreting alkenone-based reconstructions of pCO2. Article in Journal/Newspaper ice core Unknown Climate of the Past 15 2 539 554 |
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envir geo M. P. S. Badger T. B. Chalk G. L. Foster P. R. Bown S. J. Gibbs P. F. Sexton D. N. Schmidt H. Pälike A. Mackensen R. D. Pancost Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
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envir geo |
description |
Atmospheric pCO2 is a critical component of the global carbon system and is considered to be the major control of Earth's past, present, and future climate. Accurate and precise reconstructions of its concentration through geological time are therefore crucial to our understanding of the Earth system. Ice core records document pCO2 for the past 800 kyr, but at no point during this interval were CO2 levels higher than today. Interpretation of older pCO2 has been hampered by discrepancies during some time intervals between two of the main ocean-based proxy methods used to reconstruct pCO2: the carbon isotope fractionation that occurs during photosynthesis as recorded by haptophyte biomarkers (alkenones) and the boron isotope composition (δ11B) of foraminifer shells. Here, we present alkenone and δ11B-based pCO2 reconstructions generated from the same samples from the Pliocene and across a Pleistocene glacial–interglacial cycle at Ocean Drilling Program (ODP) Site 999. We find a muted response to pCO2 in the alkenone record compared to contemporaneous ice core and δ11B records, suggesting caution in the interpretation of alkenone-based records at low pCO2 levels. This is possibly caused by the physiology of CO2 uptake in the haptophytes. Our new understanding resolves some of the inconsistencies between the proxies and highlights that caution may be required when interpreting alkenone-based reconstructions of pCO2. |
format |
Article in Journal/Newspaper |
author |
M. P. S. Badger T. B. Chalk G. L. Foster P. R. Bown S. J. Gibbs P. F. Sexton D. N. Schmidt H. Pälike A. Mackensen R. D. Pancost |
author_facet |
M. P. S. Badger T. B. Chalk G. L. Foster P. R. Bown S. J. Gibbs P. F. Sexton D. N. Schmidt H. Pälike A. Mackensen R. D. Pancost |
author_sort |
M. P. S. Badger |
title |
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
title_short |
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
title_full |
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
title_fullStr |
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
title_full_unstemmed |
Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels |
title_sort |
insensitivity of alkenone carbon isotopes to atmospheric co2 at low to moderate co2 levels |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/cp-15-539-2019 https://www.clim-past.net/15/539/2019/cp-15-539-2019.pdf https://doaj.org/article/05f1c31f9be14e5fadebfcb7cb3466bb |
genre |
ice core |
genre_facet |
ice core |
op_source |
Climate of the Past, Vol 15, Pp 539-554 (2019) |
op_relation |
doi:10.5194/cp-15-539-2019 1814-9324 1814-9332 https://www.clim-past.net/15/539/2019/cp-15-539-2019.pdf https://doaj.org/article/05f1c31f9be14e5fadebfcb7cb3466bb |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/cp-15-539-2019 |
container_title |
Climate of the Past |
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15 |
container_issue |
2 |
container_start_page |
539 |
op_container_end_page |
554 |
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