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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 3, issue 3 | Copyright
Clim. Past, 3, 549-557, 2007
https://doi.org/10.5194/cp-3-549-2007
© Author(s) 2007. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.

  13 Sep 2007

13 Sep 2007

Tropical cooling and the onset of North American glaciation

P. Huybers1 and P. Molnar2 P. Huybers and P. Molnar
  • 1Department of Earth and Planetary Sciences, Harvard University, Cambridge MA, USA
  • 2Department of Geological Sciences and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder CO, USA

Abstract. We offer a test of the idea that gradual cooling in the eastern tropical Pacific led to cooling of North America and the initiation of glaciation ~3 Myr ago. Using modern climate data we estimate how warming of the eastern tropical Pacific affects North American temperature and ice-ablation. Assuming that the modern relationship holds over the past millions of years, a ~4°C warmer eastern tropical Pacific between 3–5 Ma would increase ablation in northern North America by approximately two meters per year. By comparison, a similar estimate of the ablation response to variations in Earth's obliquity gives less than half the magnitude of the tropically-induced change. Considering that variations in Earth's obliquity appear sufficient to initiate glaciations between ~1–3 Ma, we infer that the warmer eastern equatorial Pacific prior to 3 Ma suffices to preclude glaciation.

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