About ISIMIP

How does climate change affect natural and human systems already today?

How will it do so in the future?

ISIMIP was initiated by the Potsdam Institute for Climate Impact Research (PIK) and the International Institute for Applied Systems Analysis (IIASA) and has since grown to involve over 100 modelling groups from around the world.

ISIMIP3

The ISIMIP3 simulation round has started with the release of the ISIMIP3a and 3b protocols on 21 February 2020. It follows the long-term goal of harmonizing input data for a growing number of sectors. As a new sector, the fire sector has been included.

The ISIMIP3a protocol focuses on i) impact model evaluation and improvement and ii) detection and attribution of observed impacts according to the framework of the IPCC WGII-AR5 Chapter 18 definition. As a major update, it thus includes a counterfactual “no-climate change baseline” (detrended climate + observed socio-economic forcing).

The ISIMIP3b protocol is dedicated to a quantification of climate-related risks at different levels of climate change and socio-economic conditions. A particular focus is put on providing socioeconomic forcing data that account for different adaptation scenarios (group III simulations). Simulations that include future changes of socioeconomic drivers are intended to start in summer 2021.

ISIMIP2b

ISIMIP2b considers impacts on different sectors at the global and regional scales: water, fisheries and marine ecosystems, energy supply and demand, forests, biomes, agriculture, agro-economics, terrestrial biodiversity, permafrost, coastal systems, health and lakes. There is a collection of sector-specific focus regions for this simulation round. However, simulation data for all world regions are 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 is 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)'.

ISIMIP2a

ISIMIP2a includes modelling intercomparison efforts in fisheries, permafrost, biodiversity, regional water, forests and energy, as well as those sectors already covered in the Fast Track. This will serve as a basis for model evaluation and improvement, allowing for improved estimates of the biophysical and socio-economic impacts of climate change at different levels of global warming. It also provides a unique opportunity for cross-sectoral integration.

A set of chosen focus regions was developed in conjunction with participants prior to and during the Side Event. In these focus regions global and regional models. All participants running regional (i.e. below global-scale) models are asked to set up and run their models for as large a part of each focus region as possible, in order to obtain maximal spatial overlap with other models.

The focus topic for ISIMIP2a is model validation, in particular with respect to the representation of impacts of extreme weather events and climate variability. During this phase we will provide a common global observational climate data set across all impact models and sectors. In addition, appropriate observational data sets of impacts for each sector have been identified, against which the models can be benchmarked. Access to all these data is provided through a central online ISIMIP archive.

In addition, models that have participated in the Fast Track are asked to run a number of new scenarios that focus on enhanced cross-sectoral integration. These new scenarios have been developed in close collaboration with the sectoral coordinators and in consultation with all participating modelling groups. For example, the water and biomes models will take as input the land-use change patterns obtained from the agro-economic models in the fast-track phase.

Please note that new models joining the second phase should run the ISIMIP fast-track climate data using the existing Fast-Track protocol in order to provide impact projections at different levels of global warming and to enable studies consistent with the existing content of the ISIMIP archive. For sectors that are new to ISIMIP, these simulations will have to await development of a sector-specific protocol.

In addition to climate data, sector-specific additional inputs are specified in the protocol and harmonized across the sectors where possible. There will be no further harmonisation of model settings. Modelling groups are asked to do the simulations based on their "default present-day parameter settings" (excluding adaptation as far as possible). As in the Fast Track, simulations allow for a quantification of “adaptive pressure” rather than impacts under various adaptation strategies.

ISIMIP Fast Track

The first ISIMIP simulation round, the ISIMIP Fast Track, ran from early 2012 until mid 2013, with a focus 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 Recommended Concentration Pathways (RCPs), making ISIMIP a natural extension of the work done within the Coupled Climate Model Intercomparison Project (CMIP).

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. Here you can find more information about downloading impact simulation data from the ISIMIP Fast Track.

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.

Contact addresses for the ISIMIP management group and the ISIMIP sector coordinators are listed below.

ISIMIP is organized in five groups, representatives of which form the steering committee which is the main decision-making body within ISIMIP. The functions of these groups, and the associated workflow, are explained in detail in the ISIMIP Mission & Implementation Document.

The day-to-day coordination of ISIMIP is the task of the management group, comprising the project leader, Dr Katja Frieler, the project manager, and the data manager.

The cross-sectoral science team performs analysis of the ISIMIP simulation data with a clear focus on cross-sectoral issues. This team is also responsible for input-data preparation, and the members act as sector-specific contact points.

Each sector has one or more sector coordinators responsible for overseeing simulations in their sector and working closely with the participating modeling teams. The sector coordinators play a key role in liaising with other sector-specific initiatives in order to minimize the overall burden on participating modelling groups.

The Scientific Advisory Board (SAB) is a voluntary group of 5-10 internationally renowned scientists offering oversight and strategic advice to ISIMIP.

The ISIMIP Scientific Advisory Board consists of renowned scientific experts in the field of climate impact modeling and is appointed per simulation round. Find out more about the current ISIMIP SAB.