History

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.

was the first ISIMIP simulation round, running from early 2012 until mid 2013 to provide cross-sectorally consistent projections of the impacts of different levels of global warming in the 21st century, ahead of the IPCC Fifth Assessment Report (AR5). Thirty-five impact modelling teams covered the agriculture, water, global biomes, coastal systems and vector-borne disease sectors at the global scale, using common scenarios from five global climate models driven by the Representative Concentration Pathways (RCPs) — establishing ISIMIP as a natural extension of the CMIP effort. Participants received pre-processed input data, with climate from the CMIP5 archive and socio-economic data based on the SSPs. Results were collected in special issues of PNAS and Earth Systems Dynamics, many cited in AR5. Here is a list of references in the AR5 to papers based on ISIMIP simulation data; the rationale of the initiative is described in a PNAS perspectives paper.

Kick-off and results workshops in 2012 and the Impacts World 2013 conference brought modellers together to compare within and across sectors and shaped the next phase of the initiative.

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.

ISIMIP3 was initiated with the release of the ISIMIP3a and ISIMIP3b protocols on 21 February 2020 and follows the long-term goal of harmonizing input data for a growing number of sectors.

ISIMIP3a focused on impact model evaluation and improvement and on the detection and attribution of observed impacts. As a major update, it included a counterfactual "no-climate change baseline" (detrended climate with observed socio-economic forcing).

ISIMIP3b quantified climate-related risks at different levels of climate change and socio-economic conditions, with particular focus on socio-economic forcing data accounting for different adaptation scenarios (group III simulations). A fast-track subset of ISIMIP3b simulations provided early projections that were used in the IPCC Sixth Assessment Report (AR6).