title: Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records.
abstract: Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.
authors: Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK.
authors: M A
authors: MA
authors: Martínez-Botí
authors: Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK.
authors: G L
authors: GL
authors: Foster
authors: Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK.
authors: T B
authors: TB
authors: Chalk
authors: 1] Ocean and Earth Science, University of Southampton, National Oceanography Centre Southampton, Southampton, SO14 3ZH, UK [2] Research School of Earth Sciences, The Australian National University, Canberra, Australian Capital Territory 2601, Australia.
authors: E J
authors: EJ
authors: Rohling
authors: Centre for Earth, Planetary, Space and Astronomical Research, The Open University, Milton Keynes, MK7 6AA, UK.
authors: P F
authors: PF
authors: Sexton
authors: 1] School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK [2] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.
authors: D J
authors: DJ
authors: Lunt
authors: 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors: R D
authors: RD
authors: Pancost
authors: 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] Organic Geochemistry Unit, School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors: M P S
authors: MP
authors: Badger
authors: 1] The Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK [2] School of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, UK.
authors: D N
authors: DN
authors: Schmidt
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D001895:Boron / Q000032:analysis / Q000737:chemistry; D002245:Carbon Dioxide / Q000032:analysis*; D002980:Climate; D005246:Feedback; D056908:Foraminifera / Q000378:metabolism; D019015:Geologic Sediments / Q000737:chemistry; D049690:History, Ancient; D006863:Hydrogen-Ion Concentration; D046448:Ice Cover; D009792:Oceans and Seas; D010103:Oxygen Isotopes; D013696:Temperature; D013997:Time Factors
chemical_list: D010103:Oxygen Isotopes; D002245:Carbon Dioxide; D001895:Boron
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