title: Patterns and mechanisms of early Pliocene warmth.
abstract: About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions.
authors.affiliation: Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06511, USA. alexey.fedorov@yale.edu
authors.forename: A V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: C M
authors.initials: CM
authors.lastname: Brierley
authors.forename: K T
authors.initials: KT
authors.lastname: Lawrence
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: P S
authors.initials: PS
authors.lastname: Dekens
authors.forename: A C
authors.initials: AC
authors.lastname: Ravelo
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002245:Carbon Dioxide / Q000032:analysis; D002980:Climate; D057231:Climate Change / Q000266:history* / Q000706:statistics & numerical data; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry; D057232:Global Warming / Q000266:history / Q000706:statistics & numerical data; D049690:History, Ancient; D046448:Ice Cover; D008962:Models, Theoretical; D009792:Oceans and Seas; D012623:Seawater / Q000032:analysis*; D013696:Temperature
chemical_list: D002245:Carbon Dioxide
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