the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 16 Jul 2025
CMIP7 Data Request: Earth System Priorities and Opportunities
Abstract. This paper presents a comprehensive overview of the Coupled Model Intercomparison Project Phase 7 (CMIP7) request for data pertaining to Earth systems science, and provides justification for the resources needed to produce this data. Topics within the CMIP7 Earth system (CMIP7-ES) theme centre around tracking of flows of energy, carbon, water and other fluxes across domains, and constraining feedbacks between these cycles and the climate system. These topics are summarized in this paper as scientific ‘opportunities’ describing specific model intercomparison experiments and use cases for next-generation Earth System Model (ESM) output. These opportunities were submitted by modelling groups and scientific consortia following an extended public consultation process. Contained within each opportunity are requests for groups of Climate & Forecasting (CF) variables, which are bundled into variable groups representing all data required to address the opportunities’ needs. Novel opportunities in CMIP7 compared with previous phases will include running ‘emissions-driven’ simulations that integrate carbon emissions and removal scenarios with updated representations of the global carbon cycle, expanded variable groups needed to model marine trophic interactions and biogeochemistry, and data needed to understand the risk of global tipping points, among others. The production of these variables will close key gaps and uncertainties identified during previous rounds of CMIP, and support the 7th Intergovernmental Panel on Climate Change Assessment Report (AR7). We argue that CMIP7-ES data will be broadly used by scientific, policy, governmental, industry, and other communities that rely on climate model projections for research and decision making. As an author group we also reflect on the evolution of the CMIP7-ES data request as a part of a deliberative process in support of the global CMIP program.
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Status: open (until 28 Jan 2026)
- RC1: 'Comment on egusphere-2025-3246', Yanchun He, 13 Sep 2025 reply
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RC2: 'Comment on egusphere-2025-3246', Raphael Savelli, 05 Jan 2026
reply
This manuscript presents the data request for CMIP7 following rounds of consultation and calls for opportunities. It will serve as a foundational guide for modeling teams and centers to output identified variables to advance key questions in Earth System modeling and future scenarios. The manuscript and data requests are appropriate regarding the ongoing challenges to capture Earth System feedbacks and knowledge gaps. It is a great piece of work, summarizing rounds of consultation and gathering very specific variables in a very clear and compelling manuscript. The manuscript is suitable for publication in GMD following minor corrections.
As more general comments, I would suggest adding an accessible version of existing variables in a Table format, as the authors did for new variables in Annex 2, and not only json format available in Zenodo. It will make it easier and more accessible to keep track of variables and additions in the future CMIP iterations. Also, going through the data request, I identified several mentions of geoengineering and CDR. Can this be a separate opportunity in the future? How can we give these actors and these sectors a voice in future data requests? I would add this in perspectives. Finally, as a key gap, I would add more words in the perspective section on cross-sphere feedback, especially between land and ocean. How will the ocean biogeochemistry change with terrestrial runoff? The connection and especially the biogeochemical transformation across the aquatic continuum need to be better represented in models.
Minor comments:
Going through the manuscript, I identified a couple of typos (see below). I recommend doing a thorough review to correct those. Even in the tables of Annex 1 and 2.
L60: fulfil -> fulfill, check for rest of the text
L68: fulfilment -> fulfillment, check for rest of the text
L74: just removal? I would add emission/release
L85: I think the open ocean is not an issue. Representation of the coastal ocean is more challenging.
L90: I would a word on the transformation of elements when connecting reservoirs. Especially in the land-to-ocean aquatic continuum.
L44: missing a period.
L90: Yes and no. Some ESMs does not solve specific mechanisms that could cause tipping points.
I like the scientific questions, but I would also insist on or emphasize on how CMIP6 led to these questions. Just one sentence in the introductory paragraph of subsection 1.2 to make the connection with everything mentioned in subsection 1.1. The reader will appreciate that these questions are laid in CMIP’s perpetual cycle of model improvement/understanding.
1) Cycles and 2) Ecosystems: like for Energy, it is also important to look at the transformation of elements (carbon, nutrients) across realms. I don’t know if these scientific questions are still up for change, though. It is actually mentioned in subsection 1.3 Scope of the data request ‘The CMIP7-ES theme deals primarily with Earth system cycles and interactions across domains’ so maybe it is worth adding this notion of across domains in Questions 1 or 2.
4) Thresholds -> I would add, can models actually capture them? Is there a consensus among models’ detection/simulation of tipping points?
L236: I would consider non-profit organizations as a non-academic audience, too. Some organizations have the expertise to download and analyze model outputs from CMIP. Open science is essential in the framework of CMIP and these organizations need data to advocate for specific questions. They usually start the initiative and bring it to the government level for planning and policy-making.
Description of the methodology in Sections 2 and 3 is really appreciated but I would try to shorten it as much as possible. Table 1 is the main highlight. I would consider moving the rest to Supporting Information.
L290: CO2, please check the rest of the text for subscript formatting.
L300: “their Fig. 5 (land carbon cycle) and Fig. 6 (ocean carbon cycle)” Please make sure that you refer to the correct figures describing variables for land and ocean. For example, figures concerning ocean carbon start at Fig 13 in their paper.
Table 3: For each set of variables in 4.2, I would mention that these variables should directly match what is observable or closely related. I even suggest adding one sentence in the associated paragraph on making sure that models output variables that are directly or closely comparable with observations. Sometimes models are too advanced compared to observations. Not as relevant for this manuscript, we would also need better ways to compare model outputs with observations, as the latter come with temporal discontinuity and different spatial coverage.
L356: Just out of curiosity, is the change in runoff and associated solids and solutes considered in “cross-sphere feedbacks between fire and various Earth system components”? It would be relevant in 4.4.
L377: Air-sea CO2 flux is not directly output by models? Why is only abiotic carbon cycling mentioned here? How about the biological pump?
In 4.4, it would be important to mention the need to identify the variables that would allow to better constraining the role of the ocean carbon sink and then its trajectory in different scenarios.
L399:” for potential future studies of deep-sea organisms and processes” and L406:
In 4.7, I would mention if any previous CMIP6 experiments managed to capture a tipping point in the Earth System.
L558, please rephrase this sentence.
L602, sentence is missing a period.
L649: “Carbon fluxes associated and-use change” -> Carbon fluxes associated land-use change
Citation: https://doi.org/10.5194/egusphere-2025-3246-RC2
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Reviewer of "CMIP7 Data Request: Earth System Priorities and Opportunities" by McPartland et al. 2025.
The paper reviews the modelling of Earth system cycles, feedbacks, and thresholds since CMIP6, and presents a comprehensive overview of the CMIP7 data request on scientific questions (i.e., opportunities) related to the flows of energy, carbon, and water across the Earth system and their feedbacks. The authors provide rationales and describe processes for deciding on the selected opportunities to close these gaps with the CMIP7-generation model developments. The authors also justify the resources for the requested data and reflect on the challenges during the data request preparation, with suggestions for future work. The research opportunities within the CMIP7-ES theme are well explained, and their requested variable groups (and variables) are clearly presented. The paper is well written with clear structure. Once published, it will serve as a timely technical reference for the ongoing developments of the CMIP7 model data curation by modelling centers. I therefore recommend publication of the paper, with a few technical corrections as suggested below.