On this Page
We are pleased to release v1.2 of the CMIP7 Data Request. Today’s release finalises the content requested in the CMIP AR7 Fast Track Data Request.
Please note that we anticipate two additional releases across the next month: one updating the Data Request software package (API), and the other (v1.2.1) performing minor technical updates to the variables, mostly confined to the cell methods. This will result in v1.2.1 being released on 25th April 2025. However, these releases do not prevent modelling centres starting to use the Data Request to configure workflows.
The key components of the Data Request that you can access from today are:
If you would like more information about the new structure of the Data Request for CMIP7, or some background information about how the Data Request was developed, you can find this at the bottom of this page.
This release would not have been possible without the immense amount of work contributed by the Thematic Author Team members and the Data Request Task Team.
The Data Request content
The CMIP7 Data Request contains the list of variables and their associated metadata, which are requested from CMIP7 experiments. In earlier versions of the Data Request, the list of experiments was limited to the AR7 Fast Track. The latest version of the CMIP7 Data Request for the AR7 Fast Track (v1.2) includes additional experiments outside of the Fast Track.
The Data Request contains a subset of the variables which were requested in CMIP6, alongside a suite of new and modified variables. We have outlined some of the updates users can expect from both the CMIP6 Data Request and earlier version of the CMIP7 Request.
CMIP7 Data Request v1.2 launch session
The Data Request Task Team are holding a virtual launch event following the Data Request v1.2 release. The event is aimed at MIPs and Modelling Centres, though anyone from the CMIP Community is invited to register.
During the session, the Task Team and thematic author team representatives will present an overview of the request, including descriptions of the changes in structure since CMIP6, an overview of the information and tools available to you, and an update on the CMIP7 Data Request software package. There will be opportunities for questions and discussion throughout the session.
Please note, this event is being repeated across two sessions to enable participation from colleagues working in different time zones. You only need to attend one of the two meetings.
Register for Session 1: Monday 19th May, 15:00-16:00 UTC
Register for Session 2: Tuesday 20th May, 07:00-08:00 UTC
Content notes
Experiments outside of the AR7 Fast Track
A small number of experiments outside the AR7 Fast Track have been added to allow users to request data on the Fast Track timeline. These include experiments from TipMIP, FireMIP, and HighResMIP2, among others.
Time slices/subsets
Since v1.0, there has been discussion surrounding the use of time slices/subsets in the Data Request. Multiple modelling centres highlighted that they can be extremely difficult to implement, often meaning that requests for specific time slices/subsets are ignored. However, the Task Team still understands their use is appealing to some modelling centres in order to reduce particularly high volume requests. It was also noted that the term ‘Time Slice’ is used with different meanings in different communities (e.g., to refer to model simulations run under repeated annual cycle forcings).
Therefore, three decisions were made, impacting the CMIP7 Data Request:
- Time slices are renamed to time subsets from v1.1 onwards.
- Only particularly high-volume Opportunities are recommended to add time subsets. These time subsets are optional for modelling centres to implement, but provide a choice for centres if there is a need to reduce the volume of data produced.
- Currently there are details about how to implement the time subsets in the Opportunity Technical Notes.
A smaller list of time subsets is also being used in CMIP7 to simplify the request.
Baseline Climate Variables
The Baseline Climate Variables have been updated to match the final version, v1.4, as per the accepted manuscript in GMD: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2363/.
Changes in CMIP6 variables
While most of the variables from CMIP6 remain unchanged1, there are a few which have been edited. We have automatically flagged the variables which might have had one of the following fields edited since CMIP6.
- Table/physical parameter (i.e. has the variable’s compound name changed)
- Cell methods
- Cell measures
- Dimensions
- Units
- Positive direction
The updates to these fields have mostly been made to fix errors in CMIP6 variables, to add extra detail in metadata, and sometimes to adjust variable definitions or sampling. Variables with changes have been flagged in the ‘Flag – variable change since CMIP6’ field. Where a variable is flagged, we recommend comparing to the CMIP6 CMOR tables to clarify the differences; however, you will find some information in the Processing Note which will guide you towards the differences.
- Except that the frequency attribute has been modified in almost all variables and now only specifies the temporal sampling interval. ↩︎
Associating MIPs with Opportunities
Since the v1.0beta release, we have offered MIPs the chance to tag themselves to Opportunities. The options offered to MIPs are:
- If an Opportunity will produce science which is essential for their MIP. This is indicated in the field ‘MIPs – high priority.
- If the science produced by an Opportunity would be relevant for their MIP, but is not essential for their science goals. This is indicated in the field ‘MIPs – lower priority’.
Please note, we have only received responses from a few MIPs so this information is incomplete.
Making pressure levels more uniform
To make the Data Request easier to implement, the Atmospheric Author Team have proposed to move all daily and monthly data requested on the CMIP6 pressure levels plev8 and plev7h onto 19 pressure levels (plev19 from CMIP6). This was implemented from v1.0.
Sub-daily data requested from the downscaling and emulator communities are still requested on a smaller number of pressure levels, due to the potential data volume bloat a move to 19 levels could cause. Data on plev3, plev7c, and plev27 remain unchanged.
Variable names
In this release of the Data Request, variables are still identified by their compound name, as in CMIP6 (e.g. Amon.ta). The WIP have decided to use a different naming structure from CMIP7 onwards, known as ‘Branded Variables’. The details are still being finalised, but please note from v1.2.1 of the Data Request we will include the Branded Variable Label as a variable identifier. We will keep the compound name in the variable metadata to ease comparisons between CMIP7 and earlier CMIP phases.
Accessing the Data Request
The Online Database
The full Data Request can be explored online at https://bit.ly/CMIP7-DReq-v1_2.
Many users will not have used Airtable, or navigated through the CMIP Data Request database before. While it may seem complex at first, Airtable is an extremely powerful tool which makes viewing complex data structures much more simple when you know how to use it. Therefore we encourage users to take some time getting used to the platform in order to make navigation easier for yourself in the future.
We have created some guides to help you navigate and use the CMIP7 Data Request database. Access the Airtable guides at https://bit.ly/CMIP7-DReq-guidance.
The GitHub Software Package
The Data Request Task Team’s Technical Implementation Subgroup (DR-TISG) worked to create Python code to allow users to interact with the CMIP7 Data Request. It will provide an API and scripts that can produce lists of the variables requested for each CMIP7 experiment, information about the requested variables, and in general will support different ways of querying and utilising the information in the data request.
The next release of the API has a short delay and will be released on 14th April 2025. This separation of content and software timelines is important for managing Task Team and IPO workloads and allows the TISG to fix any issues in the code following the content release.
Flat list of the variables
The new structure of the Data Request is centred around Opportunities, which allows for important description of, and justification for, inclusion of output variables in the Data Request. Additionally, the database structure of the Data Request allows for improved consistency of technical metadata across the many variables in CMIP. However, we appreciate that many Data Request users find a flat list of the variables useful. This flat list is available in two ways:
- In the Variables tab of the online Airtable database. This can be exported to CSV format by clicking the MASTER button, then selecting ‘Export to CSV’.
- In the GitHub, a JSON export of variable metadata from the Airtable database is available at via the GitHub Software repo.
Providing feedback
We would like to thank the numerous thematic author team members, MIP contacts, and modelling centre representatives who have provided feedback on the Data Request at any point during the process.
Despite the incredible amount of work and review the Data Request has undergone, there will inevitably be mistakes remaining in the request. The Task Team will shortly outline their preferred feedback mechanism on v1.2 to allow users to report issues. If required, a further, minor update will be released in the summer of 2025 to address the most pressing issues.
The new CMIP7 Data Request structure and more background information
The Data Request Task Team have developed an activity that works with community representatives to devise a controlled list of high priority variables that facilitate the majority of user needs. They proposed the following structure of the next Data Request to the CMIP Panel and WGCM Infrastructure Panel (WIP). The Panel and WIP both approved the structure.
The Data Request includes variable definitions and the mapping of variables against the justification for the request expressed in terms of the opportunities that the data will generate. This will take the form of a controlled list of high priority variables that serve both the majority of user needs and create a harmonised set of data requests which balance scientific demand for data against modelling centre and infrastructure capacity.
The new CMIP7 Data Request Structure, showing how Experiment Groups and Variable Groups are linked to Opportunities.
The thematic author teams process
Five thematic author teams have been set up to develop the controlled list of high priority variables through through an IPO-supported and Data Request Task Team coordinated paper writing process.
An open call was conducted for authors and reviewers for the thematic papers:
- Impacts & adaptation (call closed on 30 November)
- Ocean & sea-ice (call closed on 01 March 2024)
- Atmosphere (call closed on 08 March 2024)
- Earth system (call closed on 08 March 2024)
- Land & land-ice (call closed on 08 March 2024)
Appointed authors can be viewed here. The Author teams will be running open meetings and other engagement initiatives with modelling centres during this process.
Variable selection
Author teams as well as the wider CMIP community have been asked to define:
- What data is requested, including CF metadata,
- Why it is needed and why it is a priority,
- Who will make use of it
- How it will be used.
Alongside discussing individual variables, the following have been asked to define:
- Experiment groups: non-exclusive grouping of experiments (e.g. ‘AR7 Fast Track’, ‘DECK’, ‘Scenarios’ etc.)
- Variable groups: non-exclusive grouping of variables (e.g. monthly time slices of the baseline variables).
- Opportunities: intended use-case/justification for one or multiple variable groups. Opportunities are also linked to relevant experiment groups.
Creating opportunities
Identifying opportunities helps to provide a structure to map variables against requirements. Each opportunity description conveys why this combination of variables and experiments is important and how variables and experiments contribute to impact.
Each opportunity includes:
- A high-level description of the science and/or societal use and impact
- A time slice to specify a block of years for which data is needed.
- Experiments and variables that link to the opportunity. Some experiments and variables will be linked to more than one opportunity.
v1.0 launch event
The Data Request Task Team held a virtual launch event following the Data Request v1.0 release. The event was aimed at MIPs and Modelling Centres, though anyone from the CMIP Community was invited to register.
During the session, the Task Team presented an overview of the request, including descriptions of the changes in structure since CMIP6, an overview of the information and tools available to you, and an introduction to the CMIP7 Data Request software package.
View the slides and recordings for the launch event here.
