Testing the assumptions in emergent constraints: why does the “emergent constraint on equilibrium climate sensitivity from global temperature variability” work for CMIP5 and not CMIP6?

Williamson, Mark S.; Cox, Peter M.; Huntingford, Chris; Nijsse, Femke J. M. M.

doi:https://doi.org/10.5194/esd-15-829-2024

Articles | Volume 15, issue 4

https://doi.org/10.5194/esd-15-829-2024

© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/esd-15-829-2024

© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 4

Research article

|

11 Jul 2024

Research article |

| 11 Jul 2024

Testing the assumptions in emergent constraints: why does the “emergent constraint on equilibrium climate sensitivity from global temperature variability” work for CMIP5 and not CMIP6?

Mark S. Williamson, Peter M. Cox, Chris Huntingford, and Femke J. M. M. Nijsse

Data sets

The Climate Model Intercomparison Project version 5 data ensemble CMIP5_database https://esgf-node.llnl.gov/projects/cmip5/

The Climate Model Intercomparison Project version 6 data ensemble CMIP6_database https://esgf-node.llnl.gov/projects/cmip6/

Short summary

Emergent constraints on equilibrium climate sensitivity (ECS) have generally got statistically weaker in the latest set of state-of-the-art climate models (CMIP6) compared to past sets (CMIP5). We look at why this weakening happened for one particular study (Cox et al, 2018) and attribute it to an assumption made in the theory that when corrected for restores there is a stronger relationship between predictor and ECS.