In preparation for the 7th Assessment Report of the IPCC, climate modellers are preparing global climate simulations that will be coordinated by the Coupled Model Intercomparison Project (CMIP). Most of these simulations require inputs that describe solar radiative forcing as well as the precipitation of energetic particles in the upper atmosphere.
This CMIP7 working group met twice (in 2023, and again in 2024) to prepare these forcing datasets, which will consist of a historical reconstruction from 1850 to the present, and scenarios from the present up to 2300. Several of the team members were already involved in the preparation of forcing datasets for CMIP6. They reviewed existing datasets for radiative and particle forcing to determine the best inputs for CMIP, defined a method to build future scenarios and estimate uncertainties, and agreed on the methodology for prescribing ozone variability in a self-consistent way in climate models without interactive chemistry.
The main outputs of this working group are a series of papers that will be submitted to the special issue of GMD on CMIP7:
- A white paper with a roadmap for making forcing datasets, published early 2024, see https://gmd.copernicus.org/articles/17/1217/2024/gmd-17-1217-2024-discussion.html
- A paper on the impact of choice of reference spectrum on atmospheric composition and tropospheric climate in WACCM6 (in preparation).
- A paper on the reconstruction of the solar spectral irradiance for CMIP7 (in preparation)
- A paper on the reconstruction of energetic particle forcing for CMIP7 (in preparation)
- A paper on the making of future scenarios for CMIP7 (in preparation)
The datasets will be made available on the HEPPA-SOLARIS website : https://solarisheppa.geomar.de/ A preliminary version has been provided in May 2024. The complete set is expected by end 2025.
Last update: 26 July 2024