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South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2

Publication ,  Journal Article
Liu, X; Battisti, DS; White, RH; Baker, PA
Published in: Journal of Climate
January 15, 2020

The Cenozoic climate of tropical South America was fundamental to the development of its biota, the most biodiverse on Earth. No previous studies have explicitly addressed how the very different atmospheric composition and Atlantic geometry during the early Eocene (approximately 55 million years ago) may have affected South American climate. At that time, the Atlantic Ocean was approximately half of its current width and the CO2 concentration of Earth's atmosphere ranged from;550 to;1500 ppm or even higher. Climate model simulations were performed to examine the effects of these major state changes on the climate of tropical South America. Reducing the width of the Atlantic by approximately half produces significant drying relative to modern climate. Drying is only partly offset by an enhancement of precipitation due to the higher CO2 of the early Eocene. The main mechanism for drier conditions is simple. Low-level air crosses the tropical Atlantic from North Africa in much less time for a narrower Atlantic (2 days) than for the modern Atlantic (;6 days); as a result, much less water is evaporated into the air and thus there is far lower moisture imported to the continent in the Eocene simulation than in the modern control. The progressive wetting (during the mid- to late Cenozoic) of the Amazon due to the widening Atlantic and the rising Andes, only partly offset by decreasing CO2 values, may have been partly responsible for the accumulating biodiversity of this region.

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Published In

Journal of Climate

DOI

ISSN

0894-8755

Publication Date

January 15, 2020

Volume

33

Issue

2

Start / End Page

691 / 706

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 3708 Oceanography
  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0909 Geomatic Engineering
  • 0405 Oceanography
  • 0401 Atmospheric Sciences
 

Citation

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Liu, X., Battisti, D. S., White, R. H., & Baker, P. A. (2020). South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2. Journal of Climate, 33(2), 691–706. https://doi.org/10.1175/JCLI-D-19-0170.1
Liu, X., D. S. Battisti, R. H. White, and P. A. Baker. “South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2.” Journal of Climate 33, no. 2 (January 15, 2020): 691–706. https://doi.org/10.1175/JCLI-D-19-0170.1.
Liu X, Battisti DS, White RH, Baker PA. South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2. Journal of Climate. 2020 Jan 15;33(2):691–706.
Liu, X., et al. “South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2.” Journal of Climate, vol. 33, no. 2, Jan. 2020, pp. 691–706. Scopus, doi:10.1175/JCLI-D-19-0170.1.
Liu X, Battisti DS, White RH, Baker PA. South American climate during the early Eocene: Impact of a narrower Atlantic and higher atmospheric CO2. Journal of Climate. 2020 Jan 15;33(2):691–706.

Published In

Journal of Climate

DOI

ISSN

0894-8755

Publication Date

January 15, 2020

Volume

33

Issue

2

Start / End Page

691 / 706

Related Subject Headings

  • Meteorology & Atmospheric Sciences
  • 3708 Oceanography
  • 3702 Climate change science
  • 3701 Atmospheric sciences
  • 0909 Geomatic Engineering
  • 0405 Oceanography
  • 0401 Atmospheric Sciences