title: Greatly expanded tropical warm pool and weakened Hadley circulation in the early Pliocene.
abstract: The Pliocene warm interval has been difficult to explain. We reconstructed the latitudinal distribution of sea surface temperature around 4 million years ago, during the early Pliocene. Our reconstruction shows that the meridional temperature gradient between the equator and subtropics was greatly reduced, implying a vast poleward expansion of the ocean tropical warm pool. Corroborating evidence indicates that the Pacific temperature contrast between the equator and 32 degrees N has evolved from approximately 2 degrees C 4 million years ago to approximately 8 degrees C today. The meridional warm pool expansion evidently had enormous impacts on the Pliocene climate, including a slowdown of the atmospheric Hadley circulation and El Niño-like conditions in the equatorial region. Ultimately, sustaining a climate state with weak tropical sea surface temperature gradients may require additional mechanisms of ocean heat uptake (such as enhanced ocean vertical mixing).
authors.affiliation: Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
authors.forename: Chris M
authors.initials: CM
authors.lastname: Brierley
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: Zhonghui
authors.initials: Z
authors.lastname: Liu
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Herbert
authors.forename: Kira T
authors.initials: KT
authors.lastname: Lawrence
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Lariviere