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Seasonal trade wind-induced upwelling along the southern margin of the Caribbean Sea occurs in response to the annual migration of the Intertropical Convergence Zone. Laminated, high deposition rate sediments of the Cariaco Basin, a small anoxic basin on the Venezuelan continental shelf, clearly record large changes in the past intensity of this upwelling. Because sediments of the Cariaco Basin are largely unbioturbated, they offer a natural opportunity to study the stable isotopic records of multiple planktonic foraminiferal taxa and to evaluate their sensitivity to both the modern hydrography and temporal changes in upwelling intensity and climate. Oxygen isotope data (δ18O) from four dominant foraminiferal taxa are presented for the time period covering the last 28 kyr. The δ18O data from Globigerina bulloides, after correction for nonequilibrium precipitation, are used as a monitor of sea surface conditions during the winter-spring upwelling season. The δ18O data from white Globigerinoides ruber are used as a measure of annual-average conditions in the near surface, while pink G. ruber data are consistent with use as an index of endmember conditions during the summer-fall nonupwelling season. Data from the deeper dwelling Neogloboquadrina dutertrei yield information on conditions near the base of the local thermocline. During the last glacial, δ18O data from G. ruber and generally reduced interspecific differences indicate cooling of surface waters over the Cariaco Basin by up to 4°C. This longer-term cooling does not appear to be related to changes in upwelling intensity along the coast but may instead reflect more regional cooling of the larger Caribbean. Superimposed on this pattern, between 12.6 and ∼10 ka, is a convergence of δ18O data between G. bulloides and N. dutertrei, implying much stronger upwelling during the last deglaciation. This scenario is consistent with other evidence for high productivity at this time. At ∼14 ka, a sharp δ18O depletion event observed in all taxa seems to have been produced by increased freshwater discharge to the southern Caribbean, suggesting either higher regional rainfall or the influence of glacial melting in the Andes. Minimum δ18O values of pink G. ruber around 6–7 ka record warmer summer sea surface temperatures and/or decreased salinity in the mid-Holocene.

This article summarizes significant research during 2000 about terrestrial atmosphere and oceans. Topics include ocean drilling, paleoclimatology, paleoceanography, and glaciology.

A description is presented of the advances made in the field of paleoceanography in 1999. Ice Age temperatures in tropical oceans, ice core paleoclimatology and seafloor methane releases are discussed.

Molybdenum (Mo) concentrations in a sediment core from the Cariaco basin on the Venezuelan continental shelf can be partitioned between a marine fraction and a terrigenous fraction. The accumulation rate of the marine fraction of Mo increased abruptly 15 000 calendar years ago (15 ka), from 4[[micro]gram [center dot] [cm.sup.-2] [center dot] [yr.sup.-1], and then decreased abruptly at 9 ka. The accumulation rate remained high throughout this 6 k.y. period, but exhibited maxima at 15-14 and 12.5 ka, corresponding in time to meltwater pulse IA into the Gulf of Mexico and the onset of the Younger Dryas cold event, respectively. The marine fraction of Mo is interpreted in terms of redox conditions of bottom water, as dictated by both the flux of settling organic matter and bottom-water residence time. Correspondence between geochemical extremes in this core with changes in sea level and global climate demonstrates the high degree to which this ocean-margin basin has responded to the paleoceanographic regime throughout the past 24 k.y.

Arising from: G. Yancheva et al. Nature 445, 74-77 (2007) On the basis of the anti-correlation of their palaeoclimatic proxy for the strength of the East Asian winter monsoon from [...]

Scientists in the fields of paleoceanography and paleoclimatology are convinced of the significance of paleoclimatic and paleoceanographic records in the study of climate variability and natural climate states. Through the use of geologic records, scientists have made various discoveries in these combined fields during 1997. Scientist Wally Broecker, for instance, gathered evidence of the link between large and abrupt glacial climate oscillations and restructuring of large-scale thermohaline circulation in the ocean.