The reconstruction of sea surface temperatures in the Pacific Ocean of 18,000 B.P.

T. C. Moore*, L. H. Burckle, K. Geitzenauer, B. Luz, A. Molina-Cruz, J. H. Robertson, H. Sachs, C. Sancetta, J. Thiede, P. Thompson, C. Wenkam

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

134 Scopus citations

Abstract

All the major microfossil groups were used to reconstruct the summer and winter sea-surface temperatures of an ice-age Pacific Ocean. The use of these four groups was necessary because of the varying degrees of preservation of siliceous and carbonate-rich sediments in the Pacific. Their use also permits comparisons of temperature estimates for samples in which more than one group is preserved. The standard error of estimate for the transfer function equations used in this study average about ± 1.5° C for the summer temperature estimates, and about ± 1.9° C for winter estimates. Laboratory (counting) errors result in an average error of estimate of about 0.6° C. Most of the individual estimates using different equations on the same samples agree within their pooled standard error. The reconstructions of ice-age temperature patterns show cooling in the subarctic region by about 4°C in both August and February. The equatorial region is 2-4° C cooler only in the winter season (August). Seasonality (August minus February temperatures) is stronger in the western Subarctic and Transition Zones at 18,000 B.P. than it is at present. Such changes in seasonality result primarily from increased winter cooling and equatorward shifts in the frontal zones. Temperatures within the centers of the subtropical gyres at 18,000 B.P. are generally as warm as, or warmer than, modern sea-surface temperatures. In particular, the Southern Hemisphere shows little or no cooling in tropical and subtropical latitudes except along the equator and in the eastern boundary current. The distribution of biotic assemblages and the derived temperature patterns indicate an intensified circulation at 18,000 B.P. Temperature gradients are steeper in the boundary currents, and divergence at the equator is increased. The "spin-up" of the subtropical gyres associated with this intensified flow appear to contain the warm tropical waters within the gyre centers, rather than allowing their dispersal to subpolar regions. These relatively warm gyre centers may act as loci for low pressure systems in the atmosphere which draw moisture away from the land masses.

Original languageEnglish
Pages (from-to)215-247
Number of pages33
JournalMarine Micropaleontology
Volume5
Issue numberC
DOIs
StatePublished - 1980

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