Dec 5, 2023

Harmonised Thematic Variables

Picture of a server room

The CMIP Data Request Task Team are seeking to work with community representative leads and engage with the wider community to devise a controlled list of high priority variables that facilitate the majority of user needs, while keeping the request as small as possible. 

Papers across identified themes (provisionally the five listed below) will define a collection of harmonised variables to support the high impact analysis of climate model output, and provide a consistent and robust set of parameters on which to build the CMIP7 archive. Each will be a collaboration between the CMIP Data Request Task Team and the MIPs and communities relevant to each theme.

The CMIP6 Data Request enabled the creation of a comprehensive and coherent database which supported and continues to support a global research and assessment effort. The CMIP7 Data Request aims to build on the successes of CMIP6, address many issues raised, particularly around easing bottlenecks and enhancing transparency, and adapt to the changing context set by plans for CMIP7 as a whole.


In order to enable an effective approach which addresses calls for both greater flexibility and for enhanced standardisation, the CMIP7 request will include three main elements: a core element utilising the baseline climate variables being prepared by a WGCM mandated author team1, a harmonised element with a high degree of standardisation and developed through topical thematic papers, and an unharmonised element which will allow flexible participation outside the harmonisation process and timeline.

Community involvement

Authors and reviewers are being sought for the five thematic papers, listed below. Initial meetings of author teams will be asked to draw up more specific descriptions of the scope of the scientific area to be covered by each paper, and of the methodology to be adopted for short-listing variables, conducting a community consultation, and using feedback to finalise a list. It is expected that each team will make use of the CMIP6 request, eliminating variables which had limited use and adding new variables to cover areas of emerging interest or new model capability. Authors will be expected to attend monthly online meetings. The list should be based on community consultation, with the authors providing a facilitation role, following the process established for the Baseline Climate Variables paper.

It is particularly important that authors consider the balance between demand for data volumes and appropriate use of modelling and infrastructure resources to supply data, while enabling the science objectives of MIPs and CMIP users. For this reason, it will be important to have representatives of the modelling community familiar with CMIP data production workflows on the author team.

Harmonisation includes not only technical harmonisation of variable descriptions but also resource allocation harmonisation between scientists, modellers and infrastructure providers. Thematic variable lists should include keywords or categorisation of variables to enable structured mapping of variables onto MIP requirements.


A  consistent list of variables will be developed across five thematic areas:

How to get involved

  1. Look at the open calls at this link. To apply, you will need to prepare:
    • A short statement describing the community that you want to represent and your relevant qualification (e.g. a specific role within a MIP or an established area of scientific competence)
    • An estimate of availability from the period the call closes to December 2024 (days per month)
  2. Contact the Data Request Task Team via CMIP IPO


  1. Baseline variables for climate model intercomparison and evaluation –  ↩︎

More on the subject


CMIP7 Data Request: Call for Earth System theme paper co-authors


CMIP7 Data Request: Call for Atmosphere theme paper co-authors


CMIP7 Data Request: Call for Land and Land-Ice theme paper co-authors

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