A State-Dependent Quantification of Climate Sensitivity Based on Paleodata of the Last 2.1 Million Years

Peter Köhler*, Lennert B. Stap, Anna S. von der Heydt, Bas de Boer, Roderik S.W. van de Wal, J. Bloch-Johnson

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The evidence from both data and models indicates that specific equilibrium climate sensitivity S[X]—the global annual mean surface temperature change (ΔTg) as a response to a change in radiative forcing X (ΔR[X])—is state dependent. Such a state dependency implies that the best fit in the scatterplot of ΔTg versus ΔR[X] is not a linear regression but can be some nonlinear or even nonsmooth function. While for the conventional linear case the slope (gradient) of the regression is correctly interpreted as the specific equilibrium climate sensitivity S[X], the interpretation is not straightforward in the nonlinear case. We here explain how such a state-dependent scatterplot needs to be interpreted and provide a theoretical understanding—or generalization—how to quantify S[X] in the nonlinear case. Finally, from data covering the last 2.1 Myr we show that—due to state dependency—the specific equilibrium climate sensitivity which considers radiative forcing of CO2 and land ice sheet (LI) albedo, S[co2,LI], is larger during interglacial states than during glacial conditions by more than a factor 2.

Original languageEnglish
Pages (from-to)1102-1114
Number of pages13
Issue number11
Publication statusPublished - 1 Nov 2017


This work contributes to PACES-II, the Helmholtz Research Programme of AWI, and to the Netherlands Earth System Science Centre (NESSC) from the Netherlands organization for scientific research (NWO). B. de Boer is funded by NWO Earth and Life Sciences (ALW), project 863.15.019. L. B. Stap was funded by NWO Earth and Life Sciences (ALW), project 822.01.006. A. von der Heydt thanks the University of Exeter for hospitality, acknowledges travel support by the (EPSRC funded) Past Earth Network (www.pastearth.net), and thanks Peter Ashwin for discussions. No new data have been generated in this study; the analyzed data are all available from the cited references.

FundersFunder number
Engineering and Physical Sciences Research Council
University of Exeter
Nederlandse Organisatie voor Wetenschappelijk Onderzoek822.01.006, 863.15.019


    • climate sensitivity
    • Pleistocene


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