General comments

This article describes the application of an ecosystem dynamics model to a global sea temperature and NPP dataset to assess the occurrence of marine heatwaves and model the impacts of these heatwaves on ecosystems.

The article is concisely written and coherent overall, though there are minor grammatical errors throughout that should be amended to improve the readability and flow of the article. There are also a couple of errors with figure captioning and formatting. Some sections within the introduction and discussion could be further expanded, as described below.

I recommend minor revisions.

Specific comments

The abstract is effective.

The introduction section is quite short, and could be expanded with more examples and some deeper explanations, but provides a concise and generally effective overview of the topic. In general, it would be helpful to give more information about why MHWs have such sizable ecological consequences. For example, you could discuss why changes in temperature cause stress and how organisms respond to this (see DOI: 10.1126/science.1163156), as well as the fact that temperatures may be more likely to exceed critical thresholds during MHWs (see DOI: 10.1016/j.tree.2021.09.003).

The Material and Method and Results sections are generally well-written. See below for grammatical corrections.

The discussion is generally well-written and explains the findings and implications of this work with an appropriate level of detail. It would be interesting to include some recommendations for future development and use of the EcoTroph-Dyn model. For example, do you think the model could be used to predict the impacts of hypothetical future MHWs at global and local scales, and how much caution should be used when interpreting these findings?

Line 622 - do you have any ideas of why the model might have underestimated ecosystem responses to MHWs? Do you have any recommendations for how people using this model could account for this uncertainty?

Line 676 - Do you think it would be possible to design a species-specific or ecosystem-specific version of the EcoTroph-Dyn model that could more precisely predict the impacts of MHWs on specified regions or ecosystem types?

Line 681 - Dismiss any possibility of what?

The conclusion section is very short. It might be useful to include a brief summary of your findings regarding the accuracy of the EcoTroph-Dyn when model compared to real-world data from ‘the Blob’.

Technical and grammatical corrections

Line 11-12 - This sentence mixes present and past tense in a way that doesn’t completely make sense; “have become longer” might sound better.

Line 46 - Verb tenses are inconsistent; “are not ubiquitous and have varied largely” would sound more consistent. Additionally, it could be informative to provide more specific details about how ecological impacts have varied between different MHW events.

Line 69 - This sentence begins with “I used” while the rest of this paragraph uses “We” - it would be better to change this to “We used” for consistency.

Line 70 - There are two opening brackets in this sentence, but only one is needed. Also, MHWs rather than MHW.

Line 90 - “the total biomass of all consumers” is clearer than “whole consumers biomass”

Line 94-95 - The list of examples should be enclosed in brackets.

Line 118 - “each TL class”.

Line 130 - “represents” rather than “representing”

Line 222 - “MHWs last” or “MHW conditions last”

Line 225 - “is a hybrid model”

Line 267 - “large spatial variability was observed in NPP changes” is grammatically clearer

Line 403 - this line should use the ≥ (greater than or equal to) symbol

Line 426 - “the ‘without MHW’ scenario”

Line 430 - “the ‘with MHWs’ scenario”

Line 470 - “congruent with the findings of…” would be grammatically clearer

Line 471 - “ecosystem functions” 

Line 473 - “ecosystem perturbations”

Line 476 - “the intensity and duration of MHWs have continuously increased”

Line 482-483 - “high TL biomass experienced greater impacts from MHWs, and was not able to recover to pre-perturbation levels as effectively as the low and medium TL biomass”

Line 585-587 - This sentence is unclear - I assume that what you mean is “the MHW was associated with a substantial increase in the abundance of pyrosomes limiting/stopping energy flow moving toward higher trophic levels (Gomes et al., 2024).”, but the grammatical structure of the sentence as written makes it somewhat difficult to follow.

Figures

Figure 3 - the caption needs to be more specific about what each panel represents.

For Figure 3a, the caption should specify how the spatial extent of MHWs was defined. Is this the percentage of the oceans’ total surface area that experienced a MHW during each year? Or the average spatial extent of each individual MHW event?

The figure keys state that Figure 3c depicts the average number of MHW days in each cell and Figure 3d depicts the average intensity of MHWs, but the figure caption states the opposite. It is also unclear whether Figure 3c depicts the average duration of each individual MHW event in days, or the total number of MHW days per year in each cell.

Figure 9 - the category labels on the X-axis are not vertically aligned with the violin plots.