Middle Miocene Southern Ocean Cooling and Antarctic Cryosphere Expansion
Digital Object Identifier (DOI)
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 CO2 (pCO2). Comparing SSTs and global carbon cycling proxies challenges the notion that episodic pCO2 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.
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Citation / Publisher Attribution
Science, v. 305, issue 5691, p. 1766-1770
Scholar Commons Citation
Shevenell, Amelia E.; Kennett, James P.; and Lea, David W., "Middle Miocene Southern Ocean Cooling and Antarctic Cryosphere Expansion" (2004). Marine Science Faculty Publications. 583.