2026-02-12 update#
CMIP7 forcings: modelling centres’ update#
This update provides the status of the delivery of the CMIP7 forcing datasets including an important notification on the historical ozone (v1.2) dataset. The homepage for CMIP7 Forcings datasets can be found here.
Request for feedback
Given the update on the error in v1.2 historical ozone dataset and scenario forcing data availability below, we would ask modelling centres to provide feedback by completing this form.
IMPORTANT: Updated dataset to address discontinuity between the PI control climatology and the historical ozone
A member of the community raised an issue with a discontinuity between the piControl climatology and the historical ozone. The full discussion is at https://github.com/PCMDI/input4MIPs_CVs/issues/400
The ozone forcing providers have uploaded an updated version (v2.0) of the historical ozone concentrations to correct for the discontinuity in v1.2. The new historical ozone forcing v2.0, which can be found at this link, has an increased historical ozone burden of about 10% (primarily due to a vertical shift in the stratospheric ozone distribution).
The CMIP Panel co-chairs are recommending that, for modelling centres who rely on ozone as an external forcing, piControl, historical, and other relevant DECK (e.g., AMIP), simulations should be re-run with the v2.0 ozone if possible. For the piControl simulation, the 1850-1870 mean of v2.0 should be used (no specific piControl file will be produced for v2.0). For those modellers who are not be able to repeat the piControl simulations, using the v1.2 PI climatology or the 1829-1849 20251025 v1.2 data is fine, since it is expected to be close to the 1850-1870 mean of v2.0.
However, it is preferable for a new historical simulation to be run with v2.0, if possible, and in advance of starting scenario simulations. If any modelling centres cannot re-run their historical simulations, they should contact the ozone forcing providers for guidance on use of future scenario ozone forcing files.
If any modelling centres run historical simulations with both v1.2 and v2.0 forcing, these simulations would be of interest to the Forcings Task Team.
Available CMIP7 scenario forcing datasets
To access the summary of CMIP7 ScenarioMIP datasets click here. The following scenario forcing datasets for the High (H) and Very Low (VL) scenarios are finalised and are now available:
(1) Anthropogenic short-lived climate forcer (SLCF) and CO2 emissions: IIASA-IAMC-vl-1-0-0; IIASA-IAMC-h-1-0-0 (DOI: 10.5281/zenodo.17981825.)
(2) Open biomass burning emissions: IIASA-IAMC-vl-1-0-0; IIASA-IAMC-h-1-0-0 (DOI: 10.5281/zenodo.17981825.)
(4) Greenhouse gas concentrations: CR-vl-1-0-0; CR-h-1-0-0 (DOI: No DOI provided.)
(6) Stratospheric volcanic SO2 emissions and aerosol optical properties: UOEXETER-ScenarioMIP-2-2-2 (No DOI provided)
PLEASE NOTE: Version 2.2.1 of the ScenarioMIP stratospheric aerosol optical properties has been updated to version 2.2.2 to fix an issue with the tropospheric mask. This issue resulted in a ~10% discrepancy between pre-industrial and ScenarioMIP stratospheric aerosol optical depth. Version 2.2.1 has been deprecated and version 2.2.2 (accessible here) should be used for ScenarioMIP runs. This only applies to ScenarioMIP files, stratospheric aerosol optical properties for DECK simulations are unchanged (version 2.2.1).
(9) Solar: SOLARIS-HEPPA-ScenarioMIP-4-6 (No DOI provided)
(12) Population density: PIK-vl-1-0-0; PIK-ln-1-0-0; PIK-l-1-0-0; PIK-ml-1-0-0; PIK-m-1-0-0; PIK-hl-1-0-0; PIK-h-1-0-0 (No DOI provided)
Please note that the van Vuuren et al. (2025) paper has been resubmitted with updates to two scenario names (VLLO becomes VL and VLHO becomes LN) plus a new scenario (HL). The updated table can be found at https://wcrp-cmip.org/mips/scenariomip/ and below. The updated or new scenarios are highlighted in bold.
| Scenario | Scenario extension | Primary emission or temperature design criteria |
|---|---|---|
| High (H) | H-ext | Emissions as high as plausible consistent with climate policy rollback |
| High Low (HL) | HL-ext | High emissions until second half of the century, followed by rapid decline to net zero CO2 in 2100 |
| Medium (M) | M-ext | Emissions consistent with current policies frozen as of 2025 |
| Medium Low (ML) | ML-ext | Medium emissions until 2040 followed by gradual decline to net zero CO2 in 2100 |
| Low (L) | L-ext | Emissions consistent with staying likely below 2C and not returning to 1.5C before end of the century |
| Very Low (VL) (Formerly Very Low Low Overshoot; VLLO) | VL-ext | Emissions consistent with limiting warming to 1.5C at the end of the century with overshoot as low as plausible |
| Low to Negative (LN) (Formerly Very Low High Overshoot; VLHO) | LN-ext | Emissions consistent with limiting warming to 1.5C at end of the century with high overshoot compared to the VL scenario. |
Following the H and VL scenario forcings delivery, the CMIP Panel has decided that M and HL will be next in the running order.
Status of outstanding datasets
Land use
Preparation of the final H and VL land use scenario forcing datasets is nearing completion and we are anticipating publication by end of February.
Ozone concentrations and nitrogen deposition
Due to delays in the dependent datasets, the delivery of H and VL ozone and nitrogen deposition scenario datasets is now estimated for 10 March.
Aerosol optical properties/MACv2-SP
The expected date for publication for H and VL aerosol plumes scenarios is end of February.
Future extensions
The timeline for future extensions will be confirmed in the coming weeks following delivery of the land use data.
Impact of delays on downstream activities
During November 2025, modelling centres completed a survey indicating likely initiation and delivery of CMIP7 DECK and Assessment Fast Track data. Around 14 centres responded that they were intending to provide piControl, historical, and H and VL scenario data by 1 July 2026 to support downstream activities including ISIMIP, CORDEX and ISMIP7. ISIMIP has recently strongly emphasised their preference to receive historical simulation data as soon as possible and scenario data ideally by May/June at the latest to allow for their contribution to AR7.
Where to ask questions and raise issues about the forcing datasets
These discussions are all being captured on the input4MIPs GitHub. Issues related to any datasets can also be raised here https://github.com/PCMDI/input4MIPs_CVs/issues. Please go to these pages to read and engage in any discussions. The page has search functionality so you can find what you need.