CMIP6: Terms of Use

To enable modeling groups and others who support CMIP6 to demonstrate its impact (and secure ongoing funding), you are required to cite and acknowledge those who have made CMIP6 possible. You also must abide by any licensing restrictions. Specifically, you must

• Adhere to licensing restrictions associated with the Creative Commons Attribution 4.0 International (CC BY 4.0) license. *Note as of October 2022 all CMIP6 contributing modeling groups have relaxed the license associated with their climate model output data. The license information available from the CMIP6 Climate Model Data license page supercedes the information stated in the “license” global attribute found in the netCDF file headers of each CMIP6 output file.
• Cite, as appropriate, one or more of the CMIP6 GMD special issue articles, which include an overview of the CMIP6 experiment design and descriptions of the CMIP6 Endorsed-MIPs, the CMIP6 forcing data sets, and the CMIP6 infrastructure.
• Cite CMIP6 model output used in your study as required by the CMIP6 Data Citation Guidelines.
• Include in publications an acknowledgment with language similar to: “We acknowledge the World Climate Research Programme, which, through its Working Group on Coupled Modelling, coordinated and promoted CMIP6. We thank the climate modeling groups for producing and making available their model output, the Earth System Grid Federation (ESGF) for archiving the data and providing access, and the multiple funding agencies who support CMIP6 and ESGF.”
• Include in publications a table listing the models and institutions that provided model output for research use. In this table and as appropriate in figure legends, use the CMIP6 “official” model names viewable as an html rendering (model names) of the CMIP6 source_id controlled vocabulary and an html rendering (institution names) of institution names recorded in the CMIP6 institution_id controlled vocabulary.
• Register any journal articles based on CMIP6 results on the CMIP6 Publications webpage. Once a DOI has been assigned by the journal, registering a paper is easy and will make IPCC authors as well as other researchers aware of your work. More importantly it will serve to document the scientific impact of CMIP6, which is of vital importance for securing future funding to support both the modeling groups and software infrastructure of CMIP.
• Refer to the collection of CMIP6 models as the “CMIP6 multi-model ensemble” (or similar) and use, as appropriate, phrases like “CMIP6 multi-model [archive/output/results/simulations/dataset/…]” to describe CMIP6 contributions and products.

The licensing agreements governing CMIP6 data depend on the model but generally conform to a standard template (nb.: the following is just an example and does not apply to all model output):

“CMIP6 model data produced by <Specific Modeling Centre Name> is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0; https://creativecommons.org/licenses/). Consult https://pcmdi.llnl.gov/CMIP6/TermsOfUse for terms of use governing CMIP6 output, including citation requirements and proper acknowledgment. Further information about this data, including some limitations, can be found via the further_info_url (recorded as a global attribute in this file). The data producers and data providers make no warranty, either express or implied, including, but not limited to, warranties of merchantability and fitness for a particular purpose. All liabilities arising from the supply of the information (including any liability arising in negligence) are excluded to the fullest extent permitted by law.”

Previously, some groups restricted use of their data under Creative Commons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA 4.0) or a Creative Commons Attribution-ShareAlike (CC BY-SA 4.0) licenses, but these more restrictive licenses were relaxed in October 2022 - with the latest license information available per model on the CMIP6 Climate Model Data license page.

General Warning:

The CMIP6 archive contains the output of scientific simulations of the past and potential future that are subject to multiple sources of error, ranging from errors in data handling, to errors in the representation of the real world in either the model, or the experimental setup for which the model was used. Different parts of the CMIP6 archive may be subject to differing levels of such errors, and users should be alert to these issues, and their potential consequences (and to the limitations of liability expressed in the data license).

Document version: 6.2 (12 October 2022)