El Nino-like pattern in ice age tropical Pacific sea surface temperature

Publication Type  Journal Article
Year of Publication  2002
Authors  Koutavas, A.; Lynch-Stieglitz, J.; Marchitto, T. M.; Sachs, J. P.
Journal Title  Science
Volume  297
Issue  5579
Pages  226-230
Journal Date  Jul 12
ISBN Number  0036-8075
Accession Number  ISI:000176738100034
Key Words  last glacial maximum; oxygen isotopic composition; south china sea; planktonic-foraminifera; equatorial pacific; late pleistocene; climate-change; rapid changes; greenland; variability

Sea surface temperatures (SSTs) in the cold tongue of the eastern equatorial Pacific exert powerful controls on global atmospheric circulation patterns. We examined climate variability in this region from the Last Glacial Maximum (LGM) to the present, using a SST record reconstructed from magnesium/calcium ratios in foraminifera from sea-floor sediments near the Galapagos Islands. Cold-tongue SST varied coherently with precession-induced changes in seasonality during the past 30,000 years. Observed LGM cooling of just 1.2degrees C implies a relaxation of tropical temperature gradients, weakened Hadley and Walker circulation, southward shift of the Intertropical Convergence Zone, and a persistent El Nino like pattern in the tropical Pacific. This is contrasted with mid-Holocene cooling suggestive of a La Nina like pattern with enhanced SST gradients and strengthened trade winds. Our results support a potent role for altered tropical Pacific SST gradients in global climate variations.


571UTTimes Cited:150Cited References Count:42

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