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Published October 4, 2007 | Supplemental Material
Journal Article Open

Persistence of full glacial conditions in the central Pacific until 15,000 years ago

Abstract

The magnitude of atmospheric cooling during the Last Glacial Maximum and the timing of the transition into the current interglacial period remain poorly constrained in tropical regions, partly because of a lack of suitable climate records. Glacial moraines provide a method of reconstructing past temperatures, but they are relatively rare in the tropics. Here we present a reconstruction of atmospheric temperatures in the central Pacific during the last deglaciation on the basis of cosmogenic ^3He ages of moraines and numerical modelling of the ice cap on Mauna Kea volcano, Hawaii—the only highland in the central Pacific on which moraines that formed during the last glacial period are preserved. Our reconstruction indicates that the Last Glacial Maximum occurred between 19,000 and 16,000 years ago in this region and that temperatures at high elevations were about 7 °C lower than today during this interval. Glacial retreat began about 16,000 years ago, but temperatures were still about 6.5 °C lower than today until 15,000 years ago. When combined with estimates of sea surface temperatures in the central Pacific Ocean, our reconstruction indicates that the lapse rate during the Last Glacial Maximum was higher than at present, which is consistent with the proposal that the atmosphere was drier at that time. Furthermore, the persistence of full glacial conditions until 15,000 years ago is consistent with the relatively late and abrupt transition to warmer temperatures in Greenland5, indicating that there may have been an atmospheric teleconnection between the central Pacific and North Atlantic regions during the last deglaciation.

Additional Information

© 2007 Nature Publishing Group. Received 22 August 2006; accepted 1 August 2007. We thank E. Bard and S. Kidder for advice on the manuscript; S. Rowland and F. Trusdell for their assistance in the field; N. Humphrey for sharing his ice-flux Matlab code; G. Leduc, C. Vincent, R. Hock, D. Paillard, N. Thouveny, S. Sépulcre and G. Brocard for discussions that helped to improve glacial modelling and palaeoclimatic interpretations; and L. Zimmerman and B. Tibari for their analytical assistance in the Centre de Recherches Pétrographiques et Géochimiques (CRPG) noble gases laboratory. We thank the State of Hawaii for delivering sampling permits. Financial support was provided by the French INSU programme 'Relief de la Terre'. Author Contributions: P.-H.B. and J.L. conducted the field work in Hawaii, numerical modelling, data interpretation and paper writing. P.-H.B. and R.P. performed the cosmogenic 3He analyses at CRPG (Nancy). P.W. provided ablation and climatic data from the Zongo glacier and helped in developing the glacier mass-balance model. D.B. participated in interpreting the cosmogenic data.

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August 19, 2023
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October 20, 2023