Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.174 IF 3.174
  • IF 5-year value: 3.841 IF 5-year 3.841
  • CiteScore value: 3.48 CiteScore 3.48
  • SNIP value: 1.078 SNIP 1.078
  • SJR value: 1.981 SJR 1.981
  • IPP value: 3.38 IPP 3.38
  • h5-index value: 42 h5-index 42
  • Scimago H index value: 58 Scimago H index 58
Discussion papers
https://doi.org/10.5194/cp-2018-152
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/cp-2018-152
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 07 Nov 2018

Research article | 07 Nov 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).

Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels

Marcus P. S. Badger1,2, Thomas B. Chalk3,4, Gavin L. Foster3, Paul R. Bown5, Samantha J. Gibbs3, Philip F. Sexton1, Daniela N. Schmidt6,7, Heiko Pälike8, Andreas Mackensen9, and Richard D. Pancost2,7 Marcus P. S. Badger et al.
  • 1School of Environment, Earth & Ecosystem Sciences, The Open University, Milton Keynes, MK7 6AA, UK
  • 2Organic Geochemistry Unit, School of Chemistry, School of Earth Sciences, University of Bristol, Bristol, BS8 1TS, UK
  • 3School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, UK
  • 4Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
  • 5Department of Earth Sciences, University College London, London, WC1E 6BT, UK
  • 6School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
  • 7The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK
  • 8MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
  • 9Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany

Abstract. 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 800kyrs, 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 Plio-Pleistocene at ODP Site 999 across a glacial-interglacial cycle. 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.

Marcus P. S. Badger et al.
Interactive discussion
Status: open (until 02 Jan 2019)
Status: open (until 02 Jan 2019)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Marcus P. S. Badger et al.
Marcus P. S. Badger et al.
Viewed  
Total article views: 454 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
357 93 4 454 9 2 8
  • HTML: 357
  • PDF: 93
  • XML: 4
  • Total: 454
  • Supplement: 9
  • BibTeX: 2
  • EndNote: 8
Views and downloads (calculated since 07 Nov 2018)
Cumulative views and downloads (calculated since 07 Nov 2018)
Viewed (geographical distribution)  
Total article views: 454 (including HTML, PDF, and XML) Thereof 449 with geography defined and 5 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
Latest update: 16 Nov 2018
Publications Copernicus
Download
Short summary
Understanding how atmospheric CO2 has effected the climate of the past is an important way of furthering our understanding of how CO2 may effect our climate in the future. There are several ways of determining CO2 in the past, in this paper we ground-truth one (based on preserved organic matter from alga) against the record of CO2 preserved as bubbles in ice cores over a glacial-interglacial cycle. We find that there is a discrepancy between the two.
Understanding how atmospheric CO2 has effected the climate of the past is an important way of...
Citation
Share