Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Context for Interpreting Equilibrium Climate Sensitivity and Transient Climate Response from the CMIP6 Earth System Models

TitleContext for Interpreting Equilibrium Climate Sensitivity and Transient Climate Response from the CMIP6 Earth System Models
Publication TypeJournal Article
Year of Publication2020
JournalScience Advances
Volume6
Number26
Pageseaba1981
Abstract / Summary

For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO2) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s. Meanwhile, the range of transient climate response (TCR, the surface temperature warming around the time of CO2 doubling in a 1% per year CO2 increase simulation) for the CMIP6 models of 1.7°C (1.3°C to 3.0°C) is only slightly larger than for the CMIP3 and CMIP5 models. Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6.

URLhttp://dx.doi.org/10.1126/sciadv.aba1981
DOI10.1126/sciadv.aba1981
Journal: Science Advances
Year of Publication: 2020
Volume: 6
Number: 26
Pages: eaba1981
Publication Date: 06/2020

For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO2) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s. Meanwhile, the range of transient climate response (TCR, the surface temperature warming around the time of CO2 doubling in a 1% per year CO2 increase simulation) for the CMIP6 models of 1.7°C (1.3°C to 3.0°C) is only slightly larger than for the CMIP3 and CMIP5 models. Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6.

DOI: 10.1126/sciadv.aba1981
Citation:
Meehl, G, C Senior, V Eyring, G Flato, J Lamarque, R Stouffer, K Taylor, and M Schlund.  2020.  "Context for Interpreting Equilibrium Climate Sensitivity and Transient Climate Response from the CMIP6 Earth System Models."  Science Advances 6(26): eaba1981.  https://doi.org/10.1126/sciadv.aba1981.