Marked decline in atmospheric carbon dioxide concentrations during the Paleogene.
The relation between the partial pressure of atmospheric carbon dioxide (pCO2) and Paleogene climate is poorly resolved. We used stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores to reconstruct pCO2 from the middle Eocene to the late Oligocene (approximately 45 to 25 million years ago). Our results demonstrate that pCO2 ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during the Oligocene, and reached modern levels by the latest Oligocene. The fall in pCO2 likely allowed for a critical expansion of ice sheets on Antarctica and promoted conditions that forced the onset of terrestrial C4 photosynthesis.
Pagani
Mark
M
Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA.
Zachos
James C
JC
Freeman
Katherine H
KH
Tipple
Brett
B
Bohaty
Stephen
S
D001272:Atmosphere; D002245:Carbon Dioxide / Q000032:analysis* / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis; D002980:Climate; D017753:Ecosystem; D056890:Eukaryota / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D007053:Ice; D010788:Photosynthesis; D010839:Phytoplankton / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D063245:Plant Development; D010944:Plants / Q000378:metabolism; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism; D013995:Time
D002247:Carbon Isotopes; D007053:Ice; D002245:Carbon Dioxide