ISIMIP3 Protocol

The ISIMIP3 protocol follows the known convention with the 3a-part addressing the historical period, and designed for model evaluation, and the 3b-part addressing historic, and future impact projections. So far, the 3b-protocol addresses group 1 (historic), and group 2 simulations (future projections with fixed socioeconomic condition), while group 3 simulations (future projections with changing socioeconomic conditions) will only be supported as soon as there is projected socioeconomic data expected to be available in the course of 2023/2024.

Please make sure to use the same model version for running 3a and 3b simulations to ensure consistent interpretation of output data.

ISIMIP3a (model evaluation + detection and attribution of observed impacts)

Historical simulations forced by observational climate, and socioeconomic information: In addition to the full forcing run (observed climate + observed socioeconomic forcing) the protocol newly includes a counterfactual “no-climate change baseline” (detrended climate + observed socioeconomic forcing) to allow for the detection and attribution of observed impacts according to the WGII-AR5 Chapter 18 definition.

ISIMIP3b (GCM-based quantification of impacts at different levels of climate change)

For ISIMIP3b we provide bias-corrected CMIP6 climate forcing for pre-industrial, historical, SSP1-RCP2.6, SSP3-RCP7.0 and SSP5-RCP8.5 conditions. The new bias-adjustment has been developed by Stefan Lange, and corrects the simulated data towards corrected ERA5 observational data (W5E5).

Check the fact sheets for further details on the counterfactual climate forcing data, the bias adjustment and basic analysis of global-mean-temperature levels in the ISIMIP3b climate data.

The ISIMIP3 protocol basically reflects the decisions taken at the Strategy Group Meeting in Potsdam, September 2018.

Access the protocol

or follow one of the direct links below. Protocol changes are documented in the related git repository.