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Evidence for a Bipolar Seesaw During the Holocene

UTIG Seminars

Evidence for a Bipolar Seesaw During the Holocene

Deborah Khider

When: Friday, Sept. 30, 2011, 10:30 a.m. to 11:30 a.m.
Join us for coffee beginning at 10:00 a.m.
Where: Seminar Conference Room, 10100 Burnet Road, Bldg 196-ROC, Austin, Texas 78758
Host: Charles Jackson, UTIG

Live Broadcast

image from Deborah's talk - click for larger view

It remains unclear whether ocean heat transport contributed to Holocene millennial-scale variability. The marine sediment core MD98-2181 (MD81) from the edge of the Western Pacific Warm Pool is used in this study to reconstruct tropical and high southern latitude ocean temperatures during the Holocene. The high temporal resolution benthic foraminiferal δ18O data documents Upper Pacific Deep Water temperature and salinity variability that originates within the Southern Ocean. Millennial-scale variability in the benthic δ18O values is on the order of ~0.1% indicating an ~0.5°C Pacific Deep Water temperature change. Further, lower deep water temperatures coincided with higher sea surface temperatures (SSTs) in the western tropical Pacific of ~0.5-1°C (estimated from the paired Mg/Ca and δ18Oc measurements on the planktonic foraminifer Globigerinoides ruber). The last millennial oscillation in the planktonic record corresponds to the Northern Hemisphere Medieval Climate Anomaly/Little Ice Age. Taken together, the tropical SST and Pacific Deep Water records suggest Southern Ocean temperature changes were anti-phased with that of the Northern Hemisphere, an observation that is consistent with a bi-polar seesaw mechanism.