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).
