Miocene evolution of atmospheric carbon dioxide
Article first published online: 4 MAY 2010
Copyright 1999 by the American Geophysical Union.
Volume 14, Issue 3, pages 273–292, June 1999
How to Cite
1999), Miocene evolution of atmospheric carbon dioxide, Paleoceanography, 14(3), 273–292, doi:10.1029/1999PA900006., , and (
- Issue published online: 4 MAY 2010
- Article first published online: 4 MAY 2010
- Manuscript Accepted: 22 JAN 1999
- Manuscript Received: 5 AUG 1998
Changes in pCO2 or ocean circulation are generally invoked to explain warm early Miocene climates and a rapid East Antarctic ice sheet (EAIS) expansion in the middle Miocene. This study reconstructs late Oligocene to late Miocene pCO2 from εp values based on carbon isotopic analyses of diunsaturated alkenones and planktonic foraminifera from Deep Sea Drilling Project sites 588 and 608 and Ocean Drilling Program site 730. Our results indicate that highest pCO2 occurred during the latest Oligocene (∼350 ppmv) but decreased rapidly at ∼25 Ma. The early and middle Miocene was characterized by low pCO2 (260–190 ppmv). Lower intervals of pCO2 correspond to inferred organic carbon burial events and glacial episodes with the lowest concentrations occurring during the middle Miocene. There is no evidence for either high pCO2 during the late early Miocene climatic optimum or a sharp pCO2 decrease associated with EAIS growth. Paradoxically, pCO2 increased following EAIS growth and obtained preindustrial levels by ∼10 Ma. Although we emphasize an oceanographic control on Miocene climate, low pCO2 could have primed the climate system to respond sensitively to changes in heat and vapor transport.