North Pacific seasonality and the glaciation of North America 2.7 million years ago

Gerald H. Haug, Andrey Ganopolski, Daniel Mikhail Sigman, Antoni Rosell-Mele, George E.A. Swann, Ralf Tiedemann, Samuel L. Jaccard, Jörg Bollmann, Mark A. Maslin, Melanie J. Leng, Geoffrey Eglinton

Research output: Contribution to journalReview articlepeer-review

332 Scopus citations


In the context of gradual Cenozoic cooling, the timing of the onset of significant Northern Hemisphere glaciation 2.7 million years ago is consistent with Milankovitch's orbital theory, which posited that ice sheets grow when polar summertime insolation and temperature are low. However, the role of moisture supply in the initiation of large Northern Hemisphere ice sheets has remained unclear. The subarctic Pacific Ocean represents a significant source of water vapour to boreal North America, but it has been largely overlooked in efforts to explain Northern Hemisphere glaciation. Here we present alkenone unsaturation ratios and diatom oxygen isotope ratios from a sediment core in the western subarctic Pacific Ocean, indicating that 2.7 million years ago late-summer sea surface temperatures in this ocean region rose in response to an increase in stratification. At the same time, winter sea surface temperatures cooled, winter floating ice became more abundant and global climate descended into glacial conditions. We suggest that the observed summer warming extended into the autumn, providing water vapour to northern North America, where it precipitated and accumulated as snow, and thus allowed the initiation of Northern Hemisphere glaciation.

Original languageEnglish (US)
Pages (from-to)821-825
Number of pages5
Issue number7028
StatePublished - Feb 24 2005

All Science Journal Classification (ASJC) codes

  • General


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