Table 3. Subsample of CMIP6 models shown in Fig. 1, with information supplied by the modeling groups regarding details of aerosol forcing and formulation and possible reasons for ECS values.
For the GFDL models, the higher sensitivities in parentheses denoted by asterisks result from longer runs and attempts to filter out unforced variability. Model acronyms are defined at https://wcrp-cmip.github.io/CMIP6_CVs/docs/CMIP6_source_id.html, and modeling groups at https://wcrp-cmip.github.io/CMIP6_CVs/docs/CMIP6_source_id.html.
| Model | ECS (K) | TCR (K) |
Aerosol ERF (W m2) |
Aerosol scheme | Reasons for ΔECS from CMIP5? |
Paper for more information |
| E3SM_1 | 5.3 | 3.0 | −1.65 | Prognostic—direct and indirect |
No CMIP5 equivalent but unusually large positive SW cloud feedback |
Golaz et al. (61) |
| CESM2 CESM2-WACCM |
5.3 4.8 |
2.0 1.9 |
−1.67 | Prognostic—direct and indirect |
Increase by >1k from CESM1 related to cloud feedbacks and aerosol-cloud interactions |
Gettelman et al. (49) |
| GFDL-CM4 GFDL-ESM4 |
3.9 (5.0*) 2.7 (3.4*) |
2.1 1.6 |
−0.7 −0.7 |
Prognostic—direct and indirect |
Preliminary investigation into the causes for this lower climate sensitivity in ESM4.1 compared to CM4.0 have indicated at least six drivers (3 –ve aerosol-climate feedbacks, −ve stratospheric ozone feedback, changes in ocean heat uptake, explicit representation of CO2) |
Held et al. (62) Winton et al. (63) |
| HadGEM3-GC3.1-LL UKESM1 |
5.5 5.4 |
2.6 2.8 |
−1.1 −1.17 |
Prognostic—direct and indirect |
Cloud-aerosol interactions and cloud microphysics |
Bodas-Salcedo et al. (50) Andrews et al. (64) Sellar et al. (65) |
| MIROC6 | 2.6 | 1.6 | −0.76 | Prognostic—direct and indirect(?) (SPRINTARS) |
Very little change from CMIP5 to CMIP6 |
Tatebe et al. (66) |
| MRI-ESM2 | 3.1 | 1.6 | −1.22 | Prognostic—direct and indirect effects |
Small increase in sensitivity (2.6–3.1) and many changes having a small impact, with largest impact possibly coming from changes to entrainment-detrainment rates (but not yet fully tested) |
Yukimoto et al. (67) |
| MPI-ESM1.2 | 3.0 | −0.6 | Specified, direct only (MACv2-SP) |
Tuned with cloud parameters to be the same as CMIP5. Pretuned version had ECS = 7 caused by a +ve low-cloud feedback in the tropics |
Mauritsen et al. (68) | |
| EC-Earth3 EC-Earth3-veg |
4.2 4.3 |
2.6 | Not yet known |
Specified, direct only (MACv2Sp) |
Early indications of the role of cloud-aerosol interactions |
Wyser et al. (69) |
| INM-CM5 INM-CM4.8 |
1.9 1.8 |
1.3 | −0.5 | Prognostic—direct effect only |
No change in ECS from CMIP5 although a lot of changes in parametrization of cloud and condensate |
|
| ACCESS-CM2 ACCESS-ESM1.5 |
4.7 3.9 |
Not yet known |
Prognostic—direct and indirect |
Using HadGEM3-GC3.1 atmospheric component, so high ECS aligned to this Using ACCESS1.3 CMIP5 model physics—little change |
||
| AWI-ESM | 3.2 | 2.2 | Not known | Specified—direct (MACv2Sp) |
No CMIP5 model, but interesting from the “parent” model, MPI-ESM |
|
| CanESM5 | 5.62 | 2.7 | Prognostic—direct and indirect effect |
Large increase since CMIP5 model (3.7–5.6)—at least half seems to be related to cloud feedback increase |
Swart et al. (70) Paper on cloud feedbacks and ECS paper planned for 2020 |
|
| NorESM2-LM | 2.5 | −1.2 | Prognostic—direct and indirect |
Small decrease since CMIP5 model (2.9–2.5), which is not yet understood |
Paper hoped for in early 2020 |
|
| IPSL-CM6A-LR | 4.6 | 2.3 | −0.6 | Specified—direct and indirect |
Lurton et al. paper planned for 2020 Servonnat et al. paper planned for 2020 |