Surface ocean conditions in the equatorial Pacific Ocean could hold the clue to whether millennial-scale global climate change during glacial times was initiated through tropical ocean–atmosphere feedbacks or by changes in the Atlantic thermohaline circulation1. North Atlantic cold periods during Heinrich events and millennial-scale cold events (stadials) have been linked with climatic changes in the tropical Atlantic Ocean and South America2,3,4, as well as the Indian and East Asian monsoon systems5,6, but not with tropical Pacific sea surface temperatures7. Here we present a high-resolution record of sea surface temperatures in the eastern tropical Pacific derived from alkenone unsaturation measurements. Our data show a temperature drop of ∼1 °C, synchronous (within dating uncertainties) with the shutdown of the Atlantic meridional overturning circulation during Heinrich event 1, and a smaller temperature drop of ∼0.5 °C synchronous with the smaller reduction in the overturning circulation during the Younger Dryas event. Both cold events coincide with maxima in surface ocean productivity as inferred from 230Th-normalized carbon burial fluxes, suggesting increased upwelling at the time. From the concurrence of equatorial Pacific cooling with the two North Atlantic cold periods during deglaciation, we conclude that these millennial-scale climate changes were probably driven by a reorganization of the oceans’ thermohaline circulation, although possibly amplified by tropical ocean–atmosphere interaction as suggested before8.
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The manuscript benefited from discussions with A. Clement, T. Delworth, D. Lea and A. Timmermann. Laboratory assistance by M. Soon, D. Montluçon, A. Fleer and S. Brown-Leger is acknowledged. This work was supported by the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), the Natural Sciences and Engineering Research Council (NSERC) of Canada, the National Science Foundation (NSF), the WHOI postdoctoral fellowship programme (M.K. and G.M.) and a fellowship of the Canadian Institute for Advanced Research (CIAR; M.K.).
This file contains Supplementary Methods, Supplementary Discussion, Supplementary Figure 1 and Supplementary Table 1. This file also contains additional references. This Supplementary Information file was updated on 30 October 2006, an incorrect version was uploaded at the time of publishing.
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Scientific Reports (2017)