the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 27 Dec 2025
The Fire Modeling Intercomparison Project (FireMIP) for CMIP7
Abstract. Fire is a global phenomenon and a key Earth system process. Extreme fire events have increased in recent years, and fire frequency and intensity are projected to rise across most regions and biomes, posing substantial challenges for ecosystems, the carbon cycle, and society. The Fire Model Intercomparison Project (FireMIP), launched in 2014, has contributed to advancing global fire modeling in Dynamic Global Vegetation Models (DGVMs) and improving understanding of fire's local drivers and local impacts on vegetation and land carbon budgets through land offline (i.e., uncoupled from the atmosphere) simulations. We now bring FireMIP into Coupled Model Intercomparison Project Phase 7 (CMIP7) to: (1) evaluate fire simulations in state-of-the-art fully coupled Earth system models (ESMs); (2) assess fire regime changes in the past, present, and future, and identify their primary natural and anthropogenic forcings and causal pathways within the Earth system, including the associated uncertainties; and (3) quantify the impacts of fires and fire changes on climate, ecosystems, and society across Earth system components, regions, and timescales, and elucidate the underlying mechanisms. FireMIP in CMIP7 will advance the fire and fire-related modeling in fully coupled ESMs, and provide a quantitative, detailed, and process-based understanding of fire's role in the Earth system by using models that incorporate critical climate feedbacks and multi-model, multi-initial-condition, and CMIP7 multi-scenario ensembles. This paper presents the motivation, scientific questions, experimental design and its rationale, model inputs and outputs, and the analysis framework for FireMIP in CMIP7, providing guidance for Earth system modeling teams conducting simulations and informing communities studying fire, climate change, and climate solutions.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Geoscientific Model Development.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.- Preprint
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2025-6115', Anonymous Referee #1, 07 Feb 2026
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RC2: 'Comment on egusphere-2025-6115', Anonymous Referee #2, 09 Feb 2026
General Comments:
This manuscript presents the well-designed protocol for integrating the Fire Model Intercomparison Project (FireMIP) into CMIP7, establishing a crucial framework for advancing global fire modeling within fully coupled Earth System Models. It clearly outlines the key scientific questions and a logical multi-experiment structure for evaluating fires, attributing changes, and quantifying impacts. The study effectively integrates fire processes into the broader Earth system perspective and demonstrates a strong awareness of observational uncertainties. However, providing further justification for key methodological choices and clarifying how consistency will be maintained across diverse modeling approaches would strengthen the protocol. Overall, this work constitutes an essential and timely reference that will significantly advance coordinated fire modeling and its integration in climate projections. The paper is worthy of publication after minor revision.
Specific Comments:
- Title Suggestion: The current title reads as a results report. To better reflect the paper's nature as a design and protocolpaper, consider revising it to:
"Conceptions and Scientific Design of the Fire Modeling Intercomparison Project (FireMIP) for CMIP7". - Explanation for Diverging Fire Indicators (P2, Lines 31-35 & P3, Lines 39-42):The text notes that while global burned area has declined in recent decades, extreme fire frequency and forest fire emissions have increased. This apparent contradiction is not explained. A brief, accessible mechanistic explanation should be added (e.g., in the Introduction or a dedicated paragraph).
- P5, L123-L25: The manuscript states that FireMIP in CMIP7 aims to improve upon CMIP6; a more explicit and structured comparison is needed. It should be clarified which specific deficiencies identified in CMIP6 fire simulations are explicitly addressed, and whether there are concrete examples where new experiment designs or outputs directly respond to past limitations.
- The manuscript strongly emphasizes evaluation against observations, but the link between evaluation metrics and process-level understanding is sometimes implicit. It needs to be explained how the proposed analyses help diagnose why models differ, rather than merely how much they differ.
- Rationale for Experimental Priority Tiers (P8, Table 1 & P9, Lines 190-200):
The manuscript labels some experiments (e.g., 2.3, 2.4) as lower priority. The scientific rationale for this prioritization is not fully explained. Please add a brief justification, such as their relative contribution to the core scientific questions or resource considerations, to guide modeling groups. - P9-P10, Group 3 experiments: For the hist-no-fire experiment, models with prescribed emissions and models with interactive fire modules implement “fire suppression” through different technical methods. It should be addressed whether the climate and carbon cycle responses to these two methods are comparable, and how this technical heterogeneity should be accounted for in the multi-model comparison of fire impacts.
- P10, L230-L234: The protocol notes that models differ in their inclusion of explicit human fire suppression. It should be elaborated how FireMIP ensures meaningful intercomparison given this heterogeneity.
- P16, L289: Given the differences in spatial resolution and parameterizations among models, the manuscript should clarify how “extreme fire” is consistently defined across CMIP7 ESMs and discuss the sensitivity of inter-model comparisons to different definitions of extreme fires.
- P17, L297-L298: The manuscript correctly notes large uncertainties among burned area and emission products, but this issue deserves deeper discussion. Guidance is needed on how discrepancies among different benchmark products should be handled in evaluation, and whether there is a recommended strategy to avoid over-interpreting model–data mismatches.
- P18, Lines 330-340: Section 5.2 discusses soil moisture but does not explicitly mention precipitation, which is a primary driver of soil moisture and fuel dryness. Can the analysis framework list precipitation as a key variable for diagnosing fire regime drivers and changes？ If can’t, why?
- Minor Comments
- P8, the header row in Table 1 reads "Group 2. Fire Impacts", but it should be corrected to "Group 3. Fire Impacts".
- Could the authors provide a clearer operational definition for the frequently used term "fire activity" and "fire regime"?
- P8, Table 1: Could the authors clarify the criteria used to determine the priority for the reader?
- P11, L243: Does “fire carbon emissions” refer exclusively to CO₂, and could the authors briefly clarify whether additional fire-related variables are considered?
- P12, L272: The term “AFS” appears without a prior definition. The authors are encouraged to define this acronym when it is first introduced.
- Selection Criteria for Input Variables (P10, Lines 235-240): A list of fire-specific inputs is provided, but the criteria for selecting these particular variables are not stated. Please add a sentence or two explaining the basis for their selection.
- Suggestion for Additional Observable Outputs (P11, Line 245): If satellite-observable variables like fire count and fire radiative power (FRP) could be included as model outputs. Adding these (if feasible for models) would greatly facilitate direct comparison with remote sensing products and should be considered.
Citation: https://doi.org/10.5194/egusphere-2025-6115-RC2 - Title Suggestion: The current title reads as a results report. To better reflect the paper's nature as a design and protocolpaper, consider revising it to:
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- 1
This protocol paper outlines the Fire Model Intercomparison Project (FireMIP) in the Coupled Model Intercomparison Project Phase 7 (CMIP7). It establishes a comprehensive experimental design, including specific simulations, required inputs and outputs, and a detailed analysis framework. The primary contribution is to provide a standardized, community-wide approach for evaluating fire simulations in Earth System Models, assessing past and future fire regime changes and their drivers, and quantifying the multifaceted impacts of fires on climate, ecosystems, and society within a fully coupled modeling framework. The protocol is clearly written and well structured. However, while the paper well describes the technical specifications and experimental design, the accompanying discussion of fire associated in-depth scientific analyses remains comparatively general and would benefit from a stronger theoretical framework or clearer metrics. Given the critical importance of fire in the earth system and the global need to reduce model uncertainties, this FireMIP paper is a substantial contribution that merits careful revision before publication.
Major Remarks:
The “recommended analyses” section requires further strengthening. Currently, its three subsections align well with the three scientific questions outlined in the paper: (1) How do models perform? (2) How do fire regimes change? (3) What is the impact? Yet the subsection titles remain overly general, limiting their ability to reflect the specific features of a FireMIP. To enhance the clarity, I recommend introducing structured subsections that explicitly reflect the unique scope and design of FireMIP. For instance, under the first question (How do models perform?), subsections could include: “Regional evaluation (e.g., permafrost fires, Amazon fires, and African fires)”, “Evaluation of burned area, fire frequency, and carbon emissions”, “Variability and sensitivity analysis”. Such structuring would better articulate the key dimensions of fire model assessments, ensuring the recommendations are tailored to the project’s objectives and actionable for future implementations.
Minor Comments:
Line 116-129: Both “scientific question 1” and “critical issue addressed by Li et al., (2024)” use “(1)”. Consider using different notations to avoid confustion.
Line 130: The key point of the second scientific question is unclear, as multiple aspects are combined without clear distinction. While Figure 1 provides a good summary of Q2, the corresponding text description (Line 132-136) lacks clarity.
Line 163-165: How to generate the initial condition for offline land model is unclear.
Line 175: Should the “Fire impacts” group 3 in Table 1?
Line 183-187: The description of 2.3 and 2.4 are different with Table 1. What is “overshoot”? Could be more specific than Table 1.
Line 190: Should “failed-policy futures” be “future failed-policy”?
Line 221-223: By comparing different experiment results, we are able to answer different questions. To summarize these potential comparisons in Figures or Tables would be helpful to enhance the clarity.
Line 226-234: How these inputs could be used in any example models could be demonstrated in Figures.
Line 239-240: Not sure how common these (2-5) inputs are used by different models. If very common, standardized inputs will help reduce uncertainties.
Line 243 &249: “driver” should be “drivers”. Not clear what does “impact variables” exactly mean.
Line 272-273: This sentence is unclear for me. Do you mean “Variables required by CMIP7 FireMIP are all listed in CMIP7 DECK and AFS experiments.”? I feel confused about “no additional requests specifically for FireMIP”. Aren’t burned area fraction and fire carbon emission specifically for FireMIP? If these two variables are already included in CMIP7 list, I don’t think it is necessary to mention this sentence.
Line 297-304: Showing the data uncertainties of fire counts and carbon emissions in Figures would be helpful to learn the quality of these benchmarks.
Line 284: Figures could be used to help demonstrate potential analysis.
Line 285-321: Only data sources were introduced in this section. What kind of metrics can be used or what aspects can be focused on should be also introduced?
Line 322: I prefer to a clearer title “Fire-related changes and corresponding drivers”.
Line 329-339: Categorizing drivers of fire-related changes would strengthen the clarity of the potential analysis.
Line 341-353: Categorizing the impact would enhance the clarity of the potential analysis.