Tropical cooling and the onset of North American glaciation

P. Huybers (1) , P. Molnar (2)

1 EPS - Department of Earth and Planetary Sciences [Cambridge, USA]
2 Department of Geological Sciences [Boulder]

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, an eastern tropical Pacific warmer by ~4° 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.

Domaines: Interfaces continentales, environnement; Sciences de la Terre

P. Huybers, P. Molnar. Tropical cooling and the onset of North American glaciation. Climate of the Past Discussions, 2007, 3 (3), pp.771-789. ⟨hal-00298186⟩