Simulation Protocols


Please find the ISIMIP3a/3b protocol on

The ISIMIP3a/3b 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 protocol addresses group 1 and group 2 simulations, while group 3 simulations will only be supported as soon as there is projected socioeconomic data available in the course of 2021.

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 socio-economic information: In addition to the full forcing run (observed climate + observed socio-economic forcing) the protocol newly includes a counterfactual “no-climate change baseline” (detrended climate + observed socio-economic forcing, see fact sheet) to allow for the detection and attribution of observed impacts according to the WGII-AR5 Chapter 18 definition.

The new counterfactual climate data has been generated by a de-trending approach using global mean temperature instead of time as independent variable. The method will soon be described in a fact sheet. Currently we only provide the GSWP3 climate forcing and its counterfactual while the combined GSWP3-W5E5 datasets will soon be provided, too.

  • 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 (see fact sheet) has been developed by Stefan Lange and corrects the simulated data towards corrected ERA5 observational data (W5E5). Basic analysis of global-mean-temperature levels in the ISIMIP3b climate data can be found here.

The ISIMIP3a/3b protocol basically reflects the decisions taken at the Strategy Group Meeting in Potsdam, September 2018.


The ISIMIP2b scenarios are designed to elicit the contribution of climate change to impacts arising from low-emissions climate-change scenarios. Pre-industrial control runs are included to facilitate statistical comparison with a no-climate-change case.

The ISIMIP2b protocol covers several new sectors, including tropical cyclones, temperature-related mortality and lakes.

The scientific rationale for the scenario design is documented in a GMD discussions paper by Frieler, et al.

Please read the data and co-authorship policy and register your model for ISIMIP2b here.

Below you will always find the latest version of the simulation protocol. Changes compared to previous versions will be recorded in the change log.

  • Important information about preparing your simulation files can be found here.
  • Information about which input data are available can be found here.
  • Basic analysis of global-mean-temperature levels in the ISIMIP2b climate data can be found here.

ISIMIP2b Protocol Changes

Aug. 8, 2019

The optional experiment IX was a simulation to test the sensitivity of the improved bias-adjustment and statistical downscaling method that will be used in ISIMIP3. Due to the relatively large effort required to process the GCM data with the new methodology (for all GCMs and all time periods) and the low interest by modellers to run the experime ...

Aug. 8, 2019

The reference to publication describing the new bias-correction method for ISIMIP3 has been added.

Aug. 8, 2019

The information from this chapter was moved completely to chapter 1 (“Scenario design”).

Aug. 8, 2019

The sector name has been changed to reflect that not only infrastructure is impacted by rising mean and extreme sea levels.


The simulation protocol contains all information necessary to run climate-impacts simulations consistent with other models participating in the current ISIMIP simulation round, ISIMIP2a. Here you will find the protocol for ISIMIP2a. Click on the link below for information about the ISIMIP Fast Track.

Information about accessing and transferring using the DKRZ server

Important information about preparing your simulation files

The protocol is divided into 15 chapters: chapters 1-5 contain important information for modellers in all sectors. Chapters 6-14 provide sector-specific instructions (can be downloaded separately below, including the references) and chapter 15 contains the references. For any queries, get in touch.

See the table below for an up-to-date list of protocol changes.

ISIMIP2a Protocol Changes

March 3, 2020

We are happy to announce the release of the ISIMIP2a-extended simulation protocol. This protocol is very similar to the ISIMIP3a protocol which we suggest to prioritize. However, we still encourage all impact modeling teams to consider performing simulations according to this ISIMIP2a-extended protocol – even if you have already contributed simu ...

Oct. 28, 2019

The correct renaming is "varsoc" instead of "man", and "nosoc" instead of "nat".Erratum for: '"man" and "nat" scenarios for forest sectors renamed to nosoc and varsoc'

March 5, 2018

To maintain consistency with other sectors, the "man" and "nat" scenarios for forest sectors have been renamed to "nosoc" and "varsoc" respectively.Erratum in

March 5, 2018

The file-naming conventions for output file has been updated to include a tag to indicate the target climate data set for the bias correction. The standard file name now has the form: <modelname>_<obs>_<bias-correction><clim_scenario>­_<socio-econ-scenario>_<sens-scenarios>_<variable>_<region>_ ...

ISIMIP Fast Track (CLOSED. For documentation only - do not use for simulations!)

FT protocol image

Complete Protocol

Last updated on 16 October, 2018.

See here for more information about the ISIMIP Fast Track.

ISIMIP-FT Protocol Changes

Oct. 16, 2018

In the file naming conventions, the qualifier for the spatial scale ("region") was missing before and has now been included. Additionally, some outdated email addresses and URLs have been updated.

March 5, 2018

The definition of the agriculture-sector output variables pirrww and pirruse have been updated to match those in the ISIMIP2b protocol.pirrww: Irrigation water withdrawal, assuming unlimited fresh-water availability and no water losses during conveyance and application. While the latter assumption has no implications for crop growth, it helps to ...