Atmospheric CO2 decline during the Pliocene intensification of Northern Hemisphere glaciations

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doi: 10.1029/2010PA002055
Author(s): Bartoli, Gretta; Hönisch, Barbel; Zeebe, Richard E.
Author Affiliation(s): Primary:
ETH Zurich, Geological Institute, Zurich, Switzerland
Lamont-Doherty Earth Observatory, United States
University of Hawaii at Manoa, United States
Volume Title: Paleoceanography
Source: Paleoceanography, 26(4). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 88 refs.; illus., incl. 1 table
Summary: Several hypotheses have been put forward to explain the onset of intensive glaciations on Greenland, Scandinavia, and North America during the Pliocene epoch between 3.6 and 2.7 million years ago (Ma). A decrease in atmospheric CO2 may have played a role during the onset of glaciations, but other tectonic and oceanic events occurring at the same time may have played a part as well. Here we present detailed atmospheric CO2 estimates from boron isotopes in planktic foraminifer shells spanning 4.6-2.0 Ma. Maximal Pliocene atmospheric CO2 estimates gradually declined from values around 410 µatm to early Pleistocene values of 300 µatm at 2.0 Ma. After the onset of large-scale ice sheets in the Northern Hemisphere, maximal pCO2 estimates were still at 2.5 Ma +90 µatm higher than values characteristic of the early Pleistocene interglacials. By contrast, Pliocene minimal atmospheric CO2 gradually decreased from 310 to 245 µatm at 3.2 Ma, coinciding with the start of transient glaciations on Greenland. Values characteristic of early Pleistocene glacial atmospheric CO2 of 200 µatm were abruptly reached after 2.7 Ma during the late Pliocene transition. This trend is consistent with the suggestion that ocean stratification and iron fertilization increased after 2.7 Ma in the North Pacific and Southern Ocean and may have led to increased glacial CO2 storage in the oceanic abyss after 2.7 Ma onward.
Year of Publication: 2011
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; B-11/B-10; Boron; Carbon dioxide; Caribbean Sea; Cenozoic; Climate change; Cocos Ridge; Colombian Basin; East Pacific; Equatorial Pacific; Foraminifera; Glaciation; Interglacial environment; Invertebrata; Isotope ratios; Isotopes; Leg 165; Leg 202; Microfossils; Neogene; North Atlantic; Northern Hemisphere; O-18/O-16; ODP Site 1241; ODP Site 999; Ocean Drilling Program; Ocean circulation; Oxygen; PH; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Pleistocene; Pliocene; Protista; Quaternary; Sea-surface temperature; Stable isotopes; Stratification; Tertiary
Coordinates: N055100 N055100 W0862700 W0862700
N124437 N124437 W0784422 W0784422
Record ID: 2014039636
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