M. B. Baker and G. H. Roe, The shape of things to come: why is climate change so predictable?, J. Clim, vol.22, pp.4574-4589, 2009.

A. Hannart, J. Dufresne, and P. Naveau, Why climate sensitivity may not be so unpredictable, Geophys. Res. Lett, vol.36, p.16707, 2009.
URL : https://hal.archives-ouvertes.fr/hal-00423477

I. Zaliapin and M. Ghil, Another look at climate sensitivity, Nonlinear Process. Geophys, vol.17, pp.113-122, 2010.
URL : https://hal.archives-ouvertes.fr/hal-01136720

R. Colman and B. Mcavaney, Climate feedbacks under a very broad range of forcing, Geophys. Res. Lett, vol.36, p.1702, 2009.

J. C. Hargreaves, A. Abe-ouchi, and J. D. Annan, Linking glacial and future climates through an ensemble of GCM simulations, Clim. Past, vol.3, pp.77-87, 2007.
URL : https://hal.archives-ouvertes.fr/hal-00298153

D. J. Lunt, On the causes of mid-Pliocene warmth and polar amplification, Earth Planet. Sci. Lett, pp.128-138, 2012.

A. M. Haywood, Are there pre-Quaternary geological analogues for a future greenhouse warming? Phil, Trans. R. Soc. A, vol.369, pp.933-956, 2011.

T. L. Edwards, M. Crucifix, and S. P. Harrison, Using the past to constrain the future: how the palaeorecord can improve estimates of global warming, Prog. Phys. Geogr, vol.31, pp.481-500, 2007.

M. Crucifix, Presents first key evidence on the state-dependence of climate sensitivity, Geophys. Res. Lett, vol.33, p.18701, 2006.

A. Laîné, M. Kageyama, P. Braconnot, and R. Alkama, Impact of greenhouse gas concentration changes on the surface energetics in the IPSL-CM4 model: regional warming patterns, land/sea warming ratio, glacial/interglacial differences, J. Clim, vol.22, pp.4621-4635, 2009.

B. L. Otto-bliesner, Status of CCSM4 Paleo CMIP5 Climate Simulations

I. M. Held, Probing the fast and slow components of global warming by returning abruptly to preindustrial forcing, J. Clim, vol.23, pp.2418-2427, 2010.

F. Joos and R. Spahni, Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years, Proc. Natl Acad. Sci. USA, vol.105, pp.1425-1430, 2008.

P. Kö-hler, G. Knorr, D. Buiron, A. Lourantou, and J. Chapellaz, Abrupt rise in atmospheric CO 2 at the onset of the Bølling/Allerød: in-situ ice core data versus true atmospheric signals, Clim. Past, vol.7, pp.473-486, 2011.

B. Hö-nisch, The geological record of ocean acidification, Science, vol.335, pp.1058-1063, 2012.

J. G. Charney, Carbon Dioxide and Climate: A Scientific Assessment, 1979.

R. Knutti and L. Tomassini, Constraints on the transient climate response from observed global temperature and ocean heat uptake, Geophys. Res. Lett, vol.35, p.9701, 2008.

J. M. Gregory and P. M. Forster, Transient climate response estimated from radiative forcing and observed temperature change, J. Geophys. Res, vol.113, p.23105, 2008.

B. J. Soden and I. M. Held, An assessment of climate feedbacks in coupled oceanatmosphere models, J. Clim, vol.19, pp.3354-3360, 2006.

M. Huber, I. Mahlstein, M. Wild, J. Fasullo, and R. Knutti, Constraints on climate sensitivity from radiation patterns in climate models, J. Clim, vol.24, pp.1034-1052, 2011.

P. Huybers, Compensation between model feedbacks and curtailment of climate sensitivity, J. Clim, vol.23, pp.3009-3018, 2010.

D. M. Lemoine, Climate sensitivity distributions dependence on the possibility that models share biases, J. Clim, vol.23, pp.4395-4415, 2010.

J. Hansen, M. Sato, P. Kharecha, and K. Von-schuckmann, Earth's energy imbalance and implications, Atmos. Chem. Phys, vol.11, pp.13421-13449, 2011.

J. M. Gregory, A new method for diagnosing radiative forcing and climate sensitivity, Geophys. Res. Lett, vol.31, p.3205, 2004.

F. Lambert, Dust-climate couplings over the past 800,000 years from the EPICA Dome C ice core, Nature, vol.452, pp.616-619, 2008.
URL : https://hal.archives-ouvertes.fr/insu-00378523

G. Winckler, R. F. Anderson, M. Q. Fleisher, D. Mcgee, and N. Mahowald, Covariant glacial-interglacial dust fluxes in the equatorial Pacific and Antarctica, Science, vol.320, pp.93-96, 2008.

A. P. Roberts, E. J. Rohling, K. M. Grant, J. C. Larrasoañ-a, and Q. Liu, Atmospheric dust variability from major global source regions over the last 500,000 years, Quat. Sci. Rev, vol.30, pp.3537-3541, 2011.

U. Ruth, D. Wagenbach, J. P. Steffensen, and M. Bigler, Continuous record of microparticle concentration and size distribution in the central Greenland NGRIP ice core during the last glacial period, J. Geophys. Res, vol.108, 2003.

B. D. Naafs, Strengthening of North American dust sources during the late Pliocene (2.7 Ma), Earth Planet. Sci. Lett, vol.8, p.19, 2012.

K. E. Kohfeld and S. P. Harrison, DIRTMAP: the geological record of dust, Earth Sci. Rev, vol.54, pp.81-114, 2001.

N. Mahowald, S. Albani, S. Engelstaedter, G. Winckler, and M. Goman, Model insight into glacial-interglacial paleodust records, Quat. Sci. Rev, vol.30, pp.832-854, 2011.

E. J. Rohling, M. Medina-elizalde, J. G. Shepherd, M. Siddall, and J. D. Stanford, Sea surface and high-latitude temperature sensitivity to radiative forcing of climate over several glacial cycles, J. Clim, vol.25, pp.1635-1656, 2012.

L. J. Gray, Solar influences on climate, Rev. Geophys, vol.48, p.4001, 2010.

M. Milankovitch, Kanon der Erdbestrahlung und seine Anwendung auf das Eiszeitenproblem, Mathematics and Natural Sciences Section, vol.133, 1941.

A. Berger, Support for the astronomical theory of climatic change, Nature, vol.269, pp.44-45, 1977.

J. Laskar, A long-term numerical solution for the insolation quantities of the Earth, Astron. Astrophys, vol.428, pp.261-285, 2004.
URL : https://hal.archives-ouvertes.fr/hal-00001603

D. J. Lunt, Earth system sensitivity inferred from Pliocene modelling and data, Nature Geosci, vol.3, pp.60-64, 2010.

, Presents a definition of Earth system sensitivity that includes both fast and slow processes, and its application to the Pliocene

J. Gregory and M. Webb, Tropospheric adjustment induces a cloud component in CO 2 forcing, J. Clim, vol.21, pp.58-71, 2008.

D. Lü-thi, High-resolution CO 2 concentration record 650,0002800,000 years before present, Nature, vol.453, pp.379-382, 2008.

L. Loulergue, Orbital and millennial-scale features of atmospheric CH 4 over the past 800,000 years, Nature, vol.453, pp.383-386, 2008.
URL : https://hal.archives-ouvertes.fr/insu-00379657

A. Schilt, Glacial-interglacial and millennial-scale variations in the atmospheric nitrous oxide concentration during the last 800,000 years, Quat. Sci. Rev, vol.29, pp.182-192, 2010.

C. Waelbroeck, Sea-level and deep water temperature changes derived from benthic foraminifera isotopic records, Quat. Sci. Rev, vol.21, pp.295-305, 2002.

E. J. Rohling, Antarctic temperature and global sea level closely coupled over the past five glacial cycles, Nature Geosci, vol.2, pp.500-504, 2009.

R. Bintanja, R. Van-de-wal, and J. Oerlemans, Modelled atmospheric temperatures and global sea levels over the past million years, Nature, vol.437, pp.125-128, 2005.

J. Hansen, Target atmospheric CO 2 : where should humanity aim? Open Atmos, Sci. J, vol.2, pp.217-231, 2008.

J. Imbrie and J. Z. Imbrie, Modeling the climatic response to orbital variations, Science, vol.207, pp.943-953, 1980.

P. Huybers and G. H. Denton, Antarctic temperature at orbital timescales controlled by local summer duration, Nature Geosci, vol.1, pp.787-792, 2008.

P. Huybers, Early Pleistocene glacial cycles and the integrated summer insolation forcing, Science, vol.313, pp.508-511, 2006.

D. J. Beerling and D. L. Royer, Fossil plants as indicators of the Phanerozoic global carbon cycle, Annu. Rev. Earth Planet. Sci, vol.30, pp.527-556, 2002.

M. Pagani, J. C. Zachos, K. H. Freeman, B. Tipple, and S. Bohaty, Marked decline in atmospheric carbon dioxide concentrations during the Paleogene, Science, vol.309, pp.600-603, 2005.

B. Hö-nisch, N. G. Hemming, D. Archer, M. Siddall, and J. F. Mcmanus, Atmospheric carbon dioxide concentration across the mid-Pleistocene transition, Science, vol.324, pp.1551-1554, 2009.

T. K. Lowenstein and R. V. Demicco, Elevated Eocene atmospheric CO 2 and its subsequent decline, Science, vol.313, p.1928, 2006.

D. J. Beerling and D. L. Royer, Convergent Cenozoic CO 2 history, Nature Geosci, vol.4, pp.418-420, 2011.

R. S. Van-de-wal, B. De-boer, L. J. Lourens, P. Kö-hler, and R. Bintanja, Reconstruction of a continuous high-resolution CO 2 record over the past 20 million years, Clim. Past, vol.7, pp.1459-1469, 2011.

, Compiles CO 2 data from a variety of approaches over the past 20 million years, and condenses these into one time series

D. J. Beerling, A. Fox, D. S. Stevenson, and P. J. Valdes, Enhanced chemistry-climate feedbacks in past greenhouse worlds, Proc. Natl Acad. Sci. USA, vol.108, pp.9770-9775, 2011.

B. De-boer, R. S. Van-de-wal, L. J. Lourens, and R. Bintanja, Transient nature of the Earth's climate and the implications for the interpretation of benthic d 18 O records, Palaeogeogr. Palaeoclimatol. Palaeoecol. 335, vol.336, pp.4-11, 2011.

B. S. Cramer, K. G. Miller, P. J. Barrett, and J. D. Wright, Late Cretaceous-Neogene trends in deep ocean temperature and continental ice volume: reconciling records of benthic foraminiferal geochemistry (d 18 O and Mg/Ca) with sea level history, J. Geophys. Res, vol.116, p.12023, 2011.

E. Gasson, Exploring uncertainties in the relationship between temperature, ice volume and sea level over the past 50 million years, Rev. Geophys, vol.50, p.1005, 2012.

J. Zachos, M. Pagani, L. Sloan, E. Thomas, and K. Billups, Trends, rhythms, and aberrations in global climate 65 Ma to present, Science, vol.292, pp.686-693, 2001.

K. G. Miller, J. D. Wright, and J. V. Browning, Visions of ice sheets in a greenhouse world, Mar. Geol, vol.217, pp.215-231, 2005.

A. Sluijs, Eustatic variations during the Paleocene-Eocene greenhouse world, Paleoceanography, vol.23, p.4216, 2008.

G. R. Dickens, M. M. Castillo, and J. C. Walker, A blast of gas in the latest Paleocene: simulating first-order effects of massive dissociation of oceanic methane hydrate, Geology, vol.25, pp.259-262, 1997.

L. J. Lourens, Astronomical pacing of late Palaeocene to early Eocene global warming events, Nature, vol.435, pp.1083-1087, 2005.

J. C. Zachos, G. R. Dickens, and R. E. Zeebe, An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics, Nature, vol.451, pp.279-283, 2008.

R. E. Zeebe, J. C. Zachos, and G. R. Dickens, Carbon dioxide forcing alone insufficient to explain Palaeocene-Eocene Thermal Maximum warming, Nature Geosci, vol.2, pp.576-580, 2009.

M. Huber and R. Caballero, The early Eocene equable climate problem revisited, Clim. Past, vol.7, pp.603-633, 2011.

C. Lorius, J. Jouzel, D. Raynaud, J. Hansen, and H. Le-treut, The ice-core record: climate sensitivity and future greenhouse warming, Nature, vol.347, pp.139-145, 1990.

V. Masson-delmotte, Past and future polar amplification of climate change: climate model intercomparisons and ice-core constraints, Clim. Dyn, vol.26, pp.513-529, 2006.
URL : https://hal.archives-ouvertes.fr/hal-00124765

D. Lea, The 100000-yr cycle in tropical SST, greenhouse gas forcing, and climate sensitivity, J. Clim, vol.17, pp.2170-2179, 2004.

J. Hansen, Climate change and trace gases, Phil. Trans. R. Soc. Lond. A, vol.365, pp.1925-1954, 2007.

P. K. Bijl, Transient Middle Eocene atmospheric CO 2 and temperature variations, Science, vol.330, pp.819-821, 2010.

A. Schmittner, Climate sensitivity estimated from temperature reconstructions of the Last Glacial Maximum, Science, vol.334, pp.1385-1388, 2011.

E. J. Rohling, Progress in palaeosalinity: overview and presentation of a new approach, Paleoceanography, vol.22, p.3215, 2007.

. Research-perspective-81, MARGO project members. Constraints on the magnitude and patterns of ocean cooling at the Last Glacial Maximum, Nature Geosci, vol.2, pp.127-132, 2009.

T. Schneider-von-deimling, A. Ganopolski, H. Held, and S. Rahmstorf, How cold was the Last Glacial Maximum?, Geophys. Res. Lett, vol.33, p.14709, 2006.

A. P. Ballantyne, M. Lavine, T. J. Crowley, J. Liu, and P. B. Baker, Meta-analysis of tropical surface temperatures during the Last Glacial Maximum, Geophys. Res. Lett, vol.32, p.5712, 2005.

J. Hansen, Climate Processes and Climate Sensitivity, vol.29, pp.130-163, 1984.

J. E. Hansen and M. Sato, Climate Change: Inferences from Paleoclimate and Regional Aspects, pp.21-48, 2012.

M. I. Hoffert and C. Covey, Deriving global climate sensitivity from palaeoclimate reconstructions, Nature, vol.360, pp.573-576, 1992.

M. Pagani, Z. Liu, J. Lariviere, and A. C. Ravelo, High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations, Nature Geosci, vol.3, pp.27-30, 2010.

C. Covey, L. C. Sloan, and M. I. Hoffert, Paleoclimate data constraints on climate sensitivity: the paleocalibration method, Clim. Change, vol.32, pp.165-184, 1996.

J. C. Zachos, L. D. Stott, and K. C. Lohmann, Evolution of early Cenozoic marine temperatures, Paleoceanography, vol.9, pp.353-387, 1994.

L. C. Sloan and E. J. Barron, A comparison of Eocene climate model results to quantified paleoclimatic interpretations, Palaeogeogr. Palaeoclimatol. Palaeoecol, vol.93, pp.183-202, 1992.

R. A. Berner, A model for atmospheric CO 2 over Phanerozoic time, Am. J. Sci, vol.291, pp.339-376, 1991.

K. H. Freeman and J. M. Hayes, Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO 2 levels, Glob. Biogeochem. Cycles, vol.6, pp.185-198, 1992.

T. E. Cerling, Carbon dioxide in the atmosphere; evidence from Cenozoic and Mesozoic paleosols, Am. J. Sci, vol.291, pp.377-400, 1991.

D. L. Royer, M. Pagani, and D. J. Beerling, Geobiological constraints on Earth system sensitivity to CO 2 during the Cretaceous and Cenozoic, Geobiology, vol.10, pp.298-310, 2012.

K. Panchuk, A. Ridgwell, and L. R. Kump, Sedimentary response to Paleocene-Eocene Thermal Maximum carbon release: a model-data comparison, Geology, vol.36, pp.315-318, 2008.

I. I. Borzenkova, Determination of global climate sensitivity to the gas composition of the atmosphere from paleoclimatic data, Izv. Atmos. Ocean. Phys, vol.39, pp.197-202, 2003.

J. Park and D. L. Royer, Geologic constraints on the glacial amplification of Phanerozoic climate sensitivity, Am. J. Sci, vol.311, pp.1-26, 2011.

G. A. Schmidt, Climate sensitivity -how sensitive is Earth's climate to CO 2 ; past, PAGES News, vol.20, p.11, 2012.

C. Wunsch and P. Heimbach, How long to oceanic tracer and proxy equilibrium?, Quat. Sci. Rev, vol.27, pp.637-651, 2008.


, We thank the Royal Netherlands Academy of Arts and Sciences (KNAW) for funding and hosting this workshop in Amsterdam, PAGES for their support, and J. Gregory for discussions, This study was supported by the UK-NERC consortium iGlass (NE/I009906/1), and 2012 Australian Laureate Fellowship FL120100050, 2011.

D. J. , E. J. , and P. , thanks the European Research Council for ERC starting grant 259627, and M.H. acknowledges NSF P2C2 grant 0902882. Some of the work was supported by grant 243908, Royal Society Wolfson Research Merit Awards. A.S

A. Contributions, E. J. , A. S. , and H. A. , initiated the PALAEOSENS workshop, and led the drafting of this study together with, The other authors contributed specialist insights, discussions and feedback

, Author Information Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests. Readers are welcome to comment on the online version of the paper. Correspondence and requests for materials should be addressed to E, J.R

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