Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene

2005/06/17 by Mark Pagani, James C. Zachos, Katherine H. Freeman +2 · 21 citations
Earth and Planetary Sciences · #Geology and Paleoclimatology Research #Paleontology and Stratigraphy of Fossils #Marine and coastal ecosystems

paper · doi:10.1126/science.1110063

openalex publication_date 2005/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/23

Abstract

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.

Citations

• Atmospheric carbon dioxide concentrations over the past 60 million years
• Significant Southern Ocean warming event in the late middle Eocene
• Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2
• High‐resolution (104 years) deep‐sea foraminiferal stable isotope records of the Eocene‐Oligocene climate transition
• Robust Convex Optimization
• GEOCARB II; a revised model of atmospheric CO 2 over Phanerozoic time
• Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present

Cited by

• Cooling and ice growth across the Eocene-Oligocene transition
• The early Eocene equable climate problem revisited
• Synchronous tropical and polar temperature evolution in the Eocene
• Chapter 8 From Greenhouse to Icehouse – The Eocene/Oligocene in Antarctica
• The Eocene Arctic Azolla bloom: environmental conditions, productivity and carbon drawdown
• An Ancient Carbon Mystery
• Late Miocene cooling coupled to carbon dioxide with Pleistocene-like climate sensitivity
• The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems
• Nature's green revolution: the remarkable evolutionary rise of C 4 plants
• Continental ice in Greenland during the Eocene and Oligocene
• Pacific Ocean and Cenozoic evolution of climate
• Late Oligocene initiation of the Antarctic Circumpolar Current: Evidence from the South Pacific
• Stepwise transition from the Eocene greenhouse to the Oligocene icehouse
• The tectonic history of Drake Passage and its possible impacts on global climate
• Atmospheric carbon dioxide through the Eocene–Oligocene climate transition
• Chapter 9 The Oligocene–Miocene Boundary – Antarctic Climate Response to Orbital Forcing
• Global Cooling During the Eocene-Oligocene Climate Transition
• Oligocene CO2 Decline Promoted C4 Photosynthesis in Grasses
• High and dry in central Tibet during the Late Oligocene
• Increased seasonality through the Eocene to Oligocene transition in northern high latitudes
• Eocene [wikipedia]