Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy
Boron isotopes in planktonic foraminifera are a widely used proxy to determine ancient surface seawater pH and by extension atmospheric CO2 concentration and climate forcing on geological timescales. Yet, to reconstruct absolute values for pH and CO2, we require a δ11Bforam-borate to pH calibration...
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Copernicus Publications
2023
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00070394 2024-01-14T10:07:38+01:00 Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy de la Vega, Elwyn Chalk, Thomas B. Hain, Mathis P. Wilding, Megan R. Casey, Daniel Gledhill, Robin Luo, Chongguang Wilson, Paul A. Foster, Gavin L. 2023-12 electronic https://doi.org/10.5194/cp-19-2493-2023 https://noa.gwlb.de/receive/cop_mods_00070394 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068743/cp-19-2493-2023.pdf https://cp.copernicus.org/articles/19/2493/2023/cp-19-2493-2023.pdf eng eng Copernicus Publications Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-19-2493-2023 https://noa.gwlb.de/receive/cop_mods_00070394 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068743/cp-19-2493-2023.pdf https://cp.copernicus.org/articles/19/2493/2023/cp-19-2493-2023.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2023 ftnonlinearchiv https://doi.org/10.5194/cp-19-2493-2023 2023-12-18T00:22:48Z Boron isotopes in planktonic foraminifera are a widely used proxy to determine ancient surface seawater pH and by extension atmospheric CO2 concentration and climate forcing on geological timescales. Yet, to reconstruct absolute values for pH and CO2, we require a δ11Bforam-borate to pH calibration and independent determinations of ocean temperature, salinity, a second carbonate parameter, and the boron isotope composition of seawater. Although δ11B-derived records of atmospheric CO2 have been shown to perform well against ice-core-based CO2 reconstructions, these tests have been performed at only a few locations and with limited temporal resolution. Here we present two highly resolved CO2 records for the late Pleistocene from Ocean Drilling Program (ODP) Sites 999 and 871. Our δ11B-derived CO2 record shows a very good agreement with the ice core CO2 record with an average offset of 13±46 (2σ) and an RMSE of 26 ppm, with minor short-lived overestimations of CO2 (of up to ∼50 ppm) occurring during some glacial onsets. We explore potential drivers of this disagreement and conclude that partial dissolution of foraminifera has a minimal effect on the CO2 offset. We also observe that the general agreement between δ11B-derived and ice core CO2 is improved by optimising the δ11Bforam-borate calibration. Despite these minor issues, a strong linear relationship between relative change in climate forcing from CO2 (from ice core data) and pH change (from δ11B) exists over the late Pleistocene, confirming that pH change is a robust proxy of climate forcing over relatively short (<1 million year) intervals. Overall, these findings demonstrate that the boron isotope proxy is a reliable indicator of CO2 beyond the reach of the ice cores and can help improve determinations of climate sensitivity for ancient time intervals. Article in Journal/Newspaper ice core Planktonic foraminifera Niedersächsisches Online-Archiv NOA Climate of the Past 19 12 2493 2510 |
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article Verlagsveröffentlichung de la Vega, Elwyn Chalk, Thomas B. Hain, Mathis P. Wilding, Megan R. Casey, Daniel Gledhill, Robin Luo, Chongguang Wilson, Paul A. Foster, Gavin L. Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
topic_facet |
article Verlagsveröffentlichung |
description |
Boron isotopes in planktonic foraminifera are a widely used proxy to determine ancient surface seawater pH and by extension atmospheric CO2 concentration and climate forcing on geological timescales. Yet, to reconstruct absolute values for pH and CO2, we require a δ11Bforam-borate to pH calibration and independent determinations of ocean temperature, salinity, a second carbonate parameter, and the boron isotope composition of seawater. Although δ11B-derived records of atmospheric CO2 have been shown to perform well against ice-core-based CO2 reconstructions, these tests have been performed at only a few locations and with limited temporal resolution. Here we present two highly resolved CO2 records for the late Pleistocene from Ocean Drilling Program (ODP) Sites 999 and 871. Our δ11B-derived CO2 record shows a very good agreement with the ice core CO2 record with an average offset of 13±46 (2σ) and an RMSE of 26 ppm, with minor short-lived overestimations of CO2 (of up to ∼50 ppm) occurring during some glacial onsets. We explore potential drivers of this disagreement and conclude that partial dissolution of foraminifera has a minimal effect on the CO2 offset. We also observe that the general agreement between δ11B-derived and ice core CO2 is improved by optimising the δ11Bforam-borate calibration. Despite these minor issues, a strong linear relationship between relative change in climate forcing from CO2 (from ice core data) and pH change (from δ11B) exists over the late Pleistocene, confirming that pH change is a robust proxy of climate forcing over relatively short (<1 million year) intervals. Overall, these findings demonstrate that the boron isotope proxy is a reliable indicator of CO2 beyond the reach of the ice cores and can help improve determinations of climate sensitivity for ancient time intervals. |
format |
Article in Journal/Newspaper |
author |
de la Vega, Elwyn Chalk, Thomas B. Hain, Mathis P. Wilding, Megan R. Casey, Daniel Gledhill, Robin Luo, Chongguang Wilson, Paul A. Foster, Gavin L. |
author_facet |
de la Vega, Elwyn Chalk, Thomas B. Hain, Mathis P. Wilding, Megan R. Casey, Daniel Gledhill, Robin Luo, Chongguang Wilson, Paul A. Foster, Gavin L. |
author_sort |
de la Vega, Elwyn |
title |
Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
title_short |
Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
title_full |
Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
title_fullStr |
Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
title_full_unstemmed |
Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy |
title_sort |
orbital co2 reconstruction using boron isotopes during the late pleistocene, an assessment of accuracy |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/cp-19-2493-2023 https://noa.gwlb.de/receive/cop_mods_00070394 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068743/cp-19-2493-2023.pdf https://cp.copernicus.org/articles/19/2493/2023/cp-19-2493-2023.pdf |
genre |
ice core Planktonic foraminifera |
genre_facet |
ice core Planktonic foraminifera |
op_relation |
Climate of the Past -- http://www.copernicus.org/EGU/cp/cp/published_papers.html -- http://www.bibliothek.uni-regensburg.de/ezeit/?2217985 -- 1814-9332 https://doi.org/10.5194/cp-19-2493-2023 https://noa.gwlb.de/receive/cop_mods_00070394 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068743/cp-19-2493-2023.pdf https://cp.copernicus.org/articles/19/2493/2023/cp-19-2493-2023.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/cp-19-2493-2023 |
container_title |
Climate of the Past |
container_volume |
19 |
container_issue |
12 |
container_start_page |
2493 |
op_container_end_page |
2510 |
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1788062023807926272 |