The Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) provides a framework for the collation of a consistent set of climate impact data across sectors and scales. It also provides a unique opportunity for considering interactions between climate change impacts across sectors through consistent scenarios.
ISIMIP is intended to be structured in successive rounds connected to the different phases of the climate model intercomparison CMIP (ISIMIP Mission & Implementation document).
The main components of the ISIMIP framework are:
- A common set of climate and other forcing data which will be distributed via a central database;
- A common modelling protocol to ensure consistency across sectors and scales in terms of data, format and experiment set-up;
- A central repository where the output data will be collected and made available to the scientific community.
::: show simulation_round=ISIMIP3a
**ISIMIP3a** is dedicated to **model evaluation** or **impact attribution**. To this end simulations are forced by observed climate and direct human forcing. In addition, a de-trended version of the observed climate allows for the generation of a *no climate change* baseline (counterfactual, if available).
To ensure consistency between ISIMIP3a and ISIMIP3b as well as the different experiments within a simulation round, we require that modelling groups use the same version of an impact model for the experiments in ISIMIP3a and ISIMIP3b.
::: show simulation_round=ISIMIP3b
**ISIMIP3b** is dedicated to a **quantification of climate-related risks** at different levels of climate change and direct human forcing. The **Group I** simulations refer to the pre-industrial and historical period of the CMIP6-based climate simulations. **Group II** covers all future projections assuming fixed 2015 levels of direct human forcing and different future projections of climate (SSP1-2.6, SSP3-7.0 and SSP5-8.5). **Group III** simulations account for future changes in the direct human forcing and are intended to be started once the corresponding direct human forcing input data are available.
To ensure consistency between ISIMIP3a and ISIMIP3b as well as the different experiments within a simulation round, we require that modelling groups use the same version of an impact model for the experiments in ISIMIP3a and ISIMIP3b.
In this protocol we describe the experiments, the different input datasets, the output variables, and how to report model results.
Throughout the protocol we use specifiers that denote a particular experiment, variable or other parameter. We use these specifiers in the tables below, in the filenames of the input data sets, and ask you to use the same specifiers in your output files. More on reporting data can be found at the end of this document.