Abstract
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 language | English |
---|---|
Pages (from-to) | 1102-1114 |
Number of pages | 13 |
Journal | Paleoceanography |
Volume | 32 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1 Nov 2017 |
Funding
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.
Funders | Funder number |
---|---|
Engineering and Physical Sciences Research Council | |
University of Exeter | |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | 822.01.006, 863.15.019 |
Keywords
- climate sensitivity
- Pleistocene