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The Common Integrated Assessment Model (CIAM) documentation

Integrated assessment modeling

Integrated assessment models (IAM) aim to provide policy-relevant insights into global environmental change and sustainable development issues by providing a quantitative description of key processes in the human and earth systems and their interactions. The modelling is integrated, i.e. it uses information from many scientific disciplines and describes both the human and earth system. The term assessment refers to focus on generating useful information for decision-making, even in case of large uncertainties. IAMs, for instance, have been successfully applied in support of climate policy (insights in future greenhouse gas emissions and options for mitigation), in several environmental assessments (e.g. the Millennium Ecosystem Assessment), but IAMs have also published a large amount of scientific papers.


For the purpose of IAMs, a transparent model documentation is essential. IAM teams have documented their models individually, often using web-supported tools. As IAMs, however, are often used together it is also important to have information on the similarities and differences across IAM models. This database provides an overview of the IAM models using a transparent wiki-based approach that has been used consistently across a range of models. This allows for direct comparison of these models. In addition to the harmonized model documentation, also Model comparison allow for direct comparisons.

Participating models

AIM-CGENational Institute for Environmental Studies (NIES), Japan, .
DNE21+Research Institute of Innovative Technology for the Earth (RITE), Japan, .
GEM-E3Institute of Communication And Computer Systems (ICCS), Greece, .
IMACLIMCentre international de recherche sur l'environnement et le développement (CIRED), France,
Societe de Mathematiques Appliquees et de Sciences Humaines (SMASH), France,
IMAGEUtrecht University (UU), Netherlands,
PBL Netherlands Environmental Assessment Agency (PBL), Netherlands,
IPETSNational Center for Atmospheric Research (NCAR), USA,
MESSAGE-GLOBIOMInternational Institute for Applied Systems Analysis (IIASA), Austria,
main users: IIASA, the MESSAGE model is distributed via the International Atomic Energy Agency (IAEA) to member countries
POLESJRC - Joint Research Centre - European Commission (EC-JRC), Belgium,
main users: - European Commission, JRC

- Universite de Grenoble UPMF, France

- Enerdata
REMINDPotsdam Institut für Klimafolgenforschung (PIK), Germany,
TIAM-UCLUniversity College London (UCL), UK,
main users: Energy modellers
WITCHFondazione Eni Enrico Mattei (FEEM), Italy,
Centro Euro-Mediterraneo sui Cambiamenti Climatici (CMCC), Italy,


The development of this wiki-based multi-model documentation received input from the FP7 ADVANCE project. The current version benefitted from the work of an earlier version developed at University College London. The wiki also benefitted from comments and suggestions of other modelling teams part of the Integrated Assessment Modelling Consortium. Integrated Assessment Model teams interested in joining this common documentation platform should contact (

Other forms of common model evaluation

IAM models also collaborate in other ways in order to enhance the transparency of IAM model output. First of all, various databases, such as the RCP and SSP databases, host the output of several IAMs in a common format (RCP Database (version 2.0)). Second, IAM models have also produced common evaluation metrics, distilled from common simple model experiments (1).


  1. ^  Elmar Kriegler, Nils Petermann, Volker Krey, Valeria Jana Schwanitz, Gunnar Luderer, Shuichi Ashina, Valentina Bosetti, Jiyong Eom, Alban Kitous, Aurélie Méjean, Leonidas Paroussos, Fuminori Sano, Hal Turton, Charlie Wilson, Detlef Van P Vuuren (2015). Diagnostic indicators for integrated assessment models of climate policy. Technological Forecasting and Social Change, 90, Part A (), 45 - 61.