The Earth System Model Evaluation Tool (ESMValTool) is a community-development that aims at improving diagnosing and understanding of the causes and effects of model biases and inter-model spread. The ESMValTool is open to both users and developers encouraging open exchange of diagnostic source code and evaluation results from the Coupled Model Intercomparison Project (CMIP) ensemble. This will facilitate and improve ESM evaluation beyond the state-of-the-art and aims at supporting the activities within CMIP and at individual modelling centers. We envisage running the ESMValTool routinely on the CMIP model output utilizing observations available through the Earth System Grid Federation (ESGF) in standard formats (obs4MIPs) or made available at ESGF nodes.

The goal is to develop a benchmarking and evaluation tool that produces well-established analyses as soon as model output from CMIP simulations becomes available, e.g., at one of the central repositories of the ESGF. This is realized through standard recipes that reproduce a certain set of diagnostics and performance metrics that have demonstrated its importance in benchmarking Earth System Models (ESMs) in a paper or assessment report, such as Chapter 9 of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) (Flato et al., 2013). The expectation is that in this way a routine and systematic evaluation of model results can be made more efficient, thereby enabling scientists to focus on developing more innovative methods of analysis rather than constantly having to “reinvent the wheel”.

In parallel to standardization of model output, the ESGF also hosts observations for Model Intercomparison Projects (obs4MIPs) and reanalyses data (ana4MIPs). obs4MIPs provides open access data sets of satellite data that are comparable in terms of variables, temporal and spatial frequency, and periods to CMIP model output (Taylor et al., 2012). The ESMValTool utilizes these observations and reanalyses from ana4MIPs plus additionally available observations in order to evaluate the models performance. In many diagnostics and metrics, more than one observational data set or meteorological reanalysis is used to assess uncertainties in observations.

The main idea of the ESMValTool is to provide a broad suite of diagnostics which can be performed easily when new model simulations are run. The suite of diagnostics needs to be broad enough to reflect the diversity and complexity of Earth System Models, but must also be robust enough to be run routinely or semi-operationally. In order the address these challenging objectives the ESMValTool is conceived as a framework which allows community contributions to be bound into a coherent framework.


Support for ESMValTool can be found in ESMValTool Discussions page where users can open an issue and a member of the User Engagement Team of ESMValTool will reply as soon as possible. This is open for all general and technical questions on the ESMValTool: installation, application, development, or any other question or comment you may have.

User mailing list

Subscribe to the ESMValTool announcements mailing list to stay up to date about new releases, monthly online meetings, upcoming workshops, and trainings.

To subscribe, send an email to with the following subject line:

  • subscribe esmvaltool


  • subscribe esmvaltool YOUR_FIRSTNAME YOUR_LASTNAME

The mailing list also has a public archive online.

Monthly meetings

We have monthly online meetings using zoom, anyone with an interest in the ESMValTool is welcome to join these meetings to connect with the community. These meetings are always announced in an issue on the ESMValTool repository and on the mailing-list.

Core development team

  • Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Germany (Co-PI)

    • ESMValTool Core Co-PI and Developer: contact for requests to use the ESMValTool and for collaboration with the development team, access to the PRIVATE GitHub repository.

  • Met Office, United Kingdom (Co-PI)

  • Alfred Wegener institute (AWI) Bremerhaven, Germany

  • Barcelona Supercomputing Center (BSC), Spain

  • Netherlands eScience Center (NLeSC), The Netherlands

  • Ludwig Maximilian University of Munich, Germany

  • Plymouth Marine Laboratory (PML), United Kingdom

  • Swedish Meteorological and Hydrological Institute (SMHI), Sweden

  • University of Bremen, Germany

  • University of Reading, United Kingdom

Recipes and diagnostics

Contacts for specific diagnostic sets are the respective authors, as listed in the corresponding recipe and diagnostic documentation and in the source code.


The ESMValTool is released under the Apache License, version 2.0. Citation of the ESMValTool paper (“Software Documentation Paper”) is kindly requested upon use, alongside with the software DOI for ESMValTool (doi:10.5281/zenodo.3401363) and ESMValCore (doi:10.5281/zenodo.3387139) and version number:

  • Righi, M., Andela, B., Eyring, V., Lauer, A., Predoi, V., Schlund, M., Vegas-Regidor, J., Bock, L., Brötz, B., de Mora, L., Diblen, F., Dreyer, L., Drost, N., Earnshaw, P., Hassler, B., Koldunov, N., Little, B., Loosveldt Tomas, S., and Zimmermann, K.: Earth System Model Evaluation Tool (ESMValTool) v2.0 – technical overview, Geosci. Model Dev., 13, 1179–1199,, 2020.

Besides the above citation, users are kindly asked to register any journal articles (or other scientific documents) that use the software at the ESMValTool webpage ( Citing the Software Documentation Paper and registering your paper(s) will serve to document the scientific impact of the Software, which is of vital importance for securing future funding. You should consider this an obligation if you have taken advantage of the ESMValTool, which represents the end product of considerable effort by the development team.