Preprints
https://doi.org/10.5194/cpd-8-4923-2012
https://doi.org/10.5194/cpd-8-4923-2012
05 Oct 2012
 | 05 Oct 2012
Status: this preprint was under review for the journal CP but the revision was not accepted.

Estimate of climate sensitivity from carbonate microfossils dated near the Eocene-Oligocene global cooling

M. W. Asten

Abstract. Climate sensitivity is a crucial parameter in global temperature modelling. An estimate is made at the time 33.4 Ma using published high-resolution deep-sea temperature proxy obtained from foraminiferal δ18O records from DSDP site 744, combined with published data for atmospheric partial pressure of CO2 (pCO2) from carbonate microfossils, where δ11B provides a proxy for pCO2. The pCO2 data shows a pCO2 decrease accompanying the major cooling event of about 4 °C from greenhouse conditions to icecap conditions following the Eocene-Oligocene boundary (33.7 My). During the cooling pCO2 fell from 1150 to 770 ppmv. The cooling event was followed by a rapid and huge increase in pCO2 back to 1130 ppmv in the space of 50 000 yr. The large pCO2 increase was accompanied by a small deep-ocean temperature increase estimated as 0.59 ± 0.063 °C. Climate sensitivity estimated from the latter is 1.1 ± 0.4 °C (66% confidence) compared with the IPCC central value of 3 °C. The post Eocene-Oligocene transition (33.4 Ma) value of 1.1 °C obtained here is lower than those published from Holocene and Pleistocene glaciation-related temperature data (800 Kya to present) but is of similar order to sensitivity estimates published from satellite observations of tropospheric and sea-surface temperature variations. The value of 1.1 °C is grossly different from estimates up to 9 °C published from paleo-temperature studies of Pliocene (3 to 4 Mya) age sediments. The range of apparent climate sensitivity values available from paleo-temperature data suggests that either feedback mechanisms vary widely for the different measurement conditions, or additional factors beyond currently used feedbacks are affecting global temperature-CO2 relationships.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
M. W. Asten
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
M. W. Asten
M. W. Asten

Viewed

Total article views: 5,355 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
3,764 1,427 164 5,355 115 147
  • HTML: 3,764
  • PDF: 1,427
  • XML: 164
  • Total: 5,355
  • BibTeX: 115
  • EndNote: 147
Views and downloads (calculated since 01 Feb 2013)
Cumulative views and downloads (calculated since 01 Feb 2013)

Saved

Latest update: 29 May 2024