A new article published in Science Advances reviews and synthesizes the latest developments in equilibrium climate sensitivity (ECS) and transient climate response (TCR) values in WCRP's Coupled Model Intercomparison Project (CMIP). The paper gives possible reasons for the higher ECS values in some of the CMIP6 models, citing cloud feedbacks and cloud-aerosol interactions as likely contributors to the higher and increased range of ECS values. The authors suggest that a major research question that needs to be pursued is "what is the actual nature and magnitude of cloud feedbacks in general and cloud-aerosol interactions in particular." They highlight the important climate sensitivity assessments undertaken by the WCRP Grand Challenge on Clouds, Circulation, and Climate Sensitivity. For the full article see:
Meehl, G. A., Senior, C. A., Eyring, V., Flato, G., Lamarque, J-F., Stouffer, R. J., Taylor, K. E., and Schlund, M. 2020. Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models, Science Advances, Vol. 6, no. 26, 24 Jun 2020, DOI: 10.1126/sciadv.aba1981.