In 2012, ISIMIP was initiated by the Potsdam Institute for Climate Impact Research (PIK) and the International Institute for Applied Systems Analysis (IIASA). Below you can read about how the initative has evolved along the different simulation rounds.

ISIMIP Fast Track

was the first ISIMIP simulation round and ran from early 2012 until mid 2013. The focus was put on on providing cross-sectorally consistent projections of the impacts of different levels of global warming in the 21st century. The common set of scenarios made use of climate projections from five Global Climate Models (GCMs) driven by the Representative Concentration Pathways (RCPs). Thus, ISIMIP was established as a natural extension of the work done within the Coupled Climate Model Intercomparison Project (CMIP).

The rationale of the initiative is described in a PNAS perspectives paper.

Fast Track simulations were submitted by 35 impact-modelling teams, covering the agriculture, water, global biomes, coastal systems and vector-borne diseases sectors all at the global scale.

This ISIMIP Fast Track provided outcomes for the IPCC’s Fifth Assessment Report (AR5). Here is a list of references in the AR5 to papers based on ISIMIP simulation data. The Fast Track also initiated a longer-term coordinated impact assessment effort driven by the impacts modelling community. The results of the Fast Track were collected in two special issues: of the Proceedings of the National Academy of Sciences (PNAS, link to special issue), and in Earth Systems Dynamics (ESD, link to special issue). Many of these papers were cited in the Fifth Assessment Report of the IPCC (AR5).

Models were provided with pre-processed input data (climate data based on the Representative Concentration Pathways (RCPs) from the CMIP5 archive, and socio-economic data based on the SSPs).

A kick-off workshop in February 2012 and a results workshop in September 2012 provided opportunities to discuss comparison within sectors as well as appropriate synthesis metrics within and across sectors.

The Impacts World 2013 conference was held in May 2013, where the state of the art in impact research was presented and plans for the next phase of ISIMIP were discussed and developed.


ISIMIP2 was separated into an ISIMIP2a simulation round focusing on model evaluation and an ISIMIP2b simulation round focusing on future projections of climate impacts. The development of the simulation round was integral part of the the Horizon 2020 project ISIpedia, led by the ISIMIP coordination group at PIK.

ISIMIP2a targeted cross-sectoral modelling intercomparison efforts serving as a basis for the focus topic of model evaluation and improvement. A particular emphasis was put on the representation of impacts of extreme weather events and climate variability. This was to allow for improved estimates of the biophysical and socioeconomic impacts of climate change at different levels of global warming.

Therefore, observed climate and socioeconomic input data was provided for participating impact models to simulate historic impacts of climate change.

A set of focus regions was developed within the ISIMIP strategy group to accommodate simulations of global and regional models.

For further information see the ISIMIP2 fact sheets and documents.

ISIMIP2b aimed at projecting climate impacts on different sectors at the global and regional scales into the future until 2100. There was a collection of sector-specific focus regions for this simulation round. However, simulation data for all world regions were welcomed, as single-model simulations for specific sites allow for model inter-comparison and potentially allow for constraining global models.
The focus topic for ISIMIP2b was to provide robust information about the impacts of 1.5°C global warming and related low-emission pathways, as required for the IPCC Special Report on this topic. The scientific rationale for the scenario design is described in detail in the paper by Frieler et al., 2017: 'Assessing the impacts of 1.5 °C global warming – simulation protocol of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b)'.

For further information see the ISIMIP2 fact sheets and documents.