Pattern decomposition of the transient climate response

Abstract

A two-pattern decomposition of the mean surface air temperature response to an increase of CO₂ is assessed. This decomposition is based on a two-layer global energy-balance model and the hypothesis of separability in space and time. It is shown that this decomposition allows the regional transient warming of a given atmosphere–ocean general circulation model to be well represented. The pattern decomposition is applied to 16 CMIP5 climate models and each of the two retrieved patterns – the equilibrium pattern and the pattern associated with the deep-ocean heat uptake – is described and discussed.

• transient regional response
• pattern scaling
• energy balance model
• climate sensitivity
• ocean heat uptake

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6. Acknowledgements

We thank the anonymous reviewers whose comments and suggestions helped to improve the manuscript. Aurélien Ribes and Hervé Douville are also thanked for helpful discussions. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and the US Department of Energy's Program for Climate Model Diagnosis and Intercomparison, which provides coordinating support and leads the development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. We thank the climate modelling groups for producing and making available their model output. This work was supported by the European Union FP7 Integrated Project COMBINE.

Notes

To access the supplementary material to this article, please see Supplementary files under Article Tools online

The 16 models analysed are BCC-CSM1-1, BNU-ESM, CanESM2, CCSM4, CNRM-CM5, CSIRO-Mk3.6.0, FGOALS-s2, GFDL-ESM2M, GISS-E2-R, HadGEM2-ES, INMCM4, IPSL-CM5A-LR, MIROC5, MPI-ESM-LR, MRI-CGCM3 and NorESM1-M, for which the values of the EBM parameters are provided in Tables 1 and 2 of G13b.