Technical Note: Calculating state dependent equilibrium climate sensitivity from palaeodata
Peter Köhler1, Lennert B. Stap2, Anna S. von der Heydt2, Bas de Boer3, and Roderik S. W. van de Wal21Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI), P.O. Box 12 01 61, 27515 Bremerhaven, Germany 2Institute for Marine and Atmospheric research Utrecht (IMAU), Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands 3School of Earth and Environment, University of Leeds, Leeds, UK
Received: 22 Feb 2016 – Accepted for review: 11 Mar 2016 – Discussion started: 15 Mar 2016
Abstract. The evidence from both data and models indicate that specific equilibrium climate sensitivity S[X] – the global annual mean surface temperature change (∆Tg) as a response to a change in radiative forcing X (∆R[X]) – is state dependent. Such a state dependency implies that the best fit in the scatter plot of ∆Tg versus ∆R[X] is not a linear regression, but for instance a higher order polynomial. 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 non-linear case. We here elaborate how such a state dependent scatter plot needs to be interpreted, and provide a theoretical understanding how to calculate S[X] in the non-linear case.
Köhler, P., Stap, L. B., von der Heydt, A. S., de Boer, B., and van de Wal, R. S. W.: Technical Note: Calculating state dependent equilibrium climate sensitivity from palaeodata, Clim. Past Discuss., doi:10.5194/cp-2016-23, 2016.