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 ∼3Myr 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 ∼l-3 Ma, we infer that the warmer eastern equatorial Pacific prior to 3 Ma suffices to preclude glaciation.
CITATION STYLE
Huybers, P., & Molnar, P. (2007). Tropical cooling and the onset of North American glaciation. Climate of the Past, 3(3), 549–557. https://doi.org/10.5194/cp-3-549-2007
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