Middle Miocene Southern Ocean Cooling and Antarctic Cryosphere Expansion

Amelia E. Shevenell, James P. Kennett, David W. Lea

Research output: Contribution to journalArticlepeer-review

Abstract

Magnesium/calcium data from Southern Ocean planktonic foraminifera demonstrate that high-latitude (∼55°S) southwest Pacific sea surface temperatures (SSTs) cooled 6° to 7°C during the middle Miocene climate transition (14.2 to 13.8 million years ago). Stepwise surface cooling is paced by eccentricity forcing and precedes Antarctic cryosphere expansion by ∼60 thousand years, suggesting the involvement of additional feedbacks during this interval of inferred low-atmospheric partial pressure of CO 2 ( p CO 2 ). Comparing SSTs and global carbon cycling proxies challenges the notion that episodic p CO 2 drawdown drove this major Cenozoic climate transition. SST, salinity, and ice-volume trends suggest instead that orbitally paced ocean circulation changes altered meridional heat/vapor transport, triggering ice growth and global cooling.

Original languageAmerican English
JournalScience
Volume305
DOIs
StatePublished - Sep 1 2004
Externally publishedYes

Disciplines

  • Life Sciences

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