* Matthew Huber
* Mark Pagani
* Pete computing cluster
* Wikipedia entry on TEX86 temperature proxy
* Wikipedia entry on alkenones temperature proxy

February 26, 2009

Prehistoric global cooling caused by CO2, research finds

WEST LAFAYETTE, Ind. - Ice in Antarctica suddenly appeared — in geologic terms — about 35 million years ago. For the previous 100 million years the continent had been essentially ice-free.
























Sources: Matthew Huber, (765) 494-9531, huberm@purdue.edu





Global cooling during the eocene-oligocene
climate transition

 Zhonghui Liu, Yale University and the University of Hong Kong; Mark Pagani and David Zinniker, Yale University; Robert DeConto, the University of Massachusetts-Amherst; Matthew Huber, Purdue University; Henk Brinkuis, Utrecht University; Sunita R. Shah, Harvard University; R. Mark Leckie, the University of Massachusetts-Amherst; Ann Pearson, Harvard University

About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report alkenone unsaturation index and TEX86 proxy sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous. High-latitude (45° to 70° in both hemispheres) temperatures before the climate transition were -20° and cooled an average of -5° C. Our results, combined with ocean and ice-sheet model simulations and benthic oxygen isotope records, indicate that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.


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