the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 Dec 2025
Underestimated Future Arctic Ocean Warming due to Unresolved Marine Heatwaves at Low Resolution
Abstract. The Arctic Ocean is projected to warm twice more than the global mean in a warming 21st century, following increased solar heat input due to sea ice decrease. Here we find that this increase in solar heat input is larger in a higher-resolution climate model compared to a low-resolution one. This is due to the impacts of Arctic marine heatwaves (MHWs), known as episodes of extreme ocean warming. The explicit consideration of MHWs, which are stronger and more realistic in higher-resolution models, increases melting of sea ice and thus solar heat input, thereby reinforcing the long-term Arctic Ocean warming. A positive feedback is identified between stronger MHWs and larger Arctic Ocean warming. We emphasize that Arctic Ocean warming is underestimated by the current generation of climate models, which generally have a too low spatial resolution to resolve Arctic MHWs. We conclude that future eddy- and storm-resolving models will provide a new perspective on the Earth system's response to past and future climate and environmental extremes.
Competing interests: Gerrit Lohmann is a member of the editorial board of ESD.
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: open (until 01 Feb 2026)
- RC1: 'Comment on egusphere-2025-5296', Anonymous Referee #1, 22 Dec 2025 reply
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1. Main comments
I have already reviewed five versions of this paper originally submitted to Nature Climate Change, and then re-submitted to Nature Communications and Earth's future. This illustrates the tenacity of the authors to make their work available to the scientific community. I think the authors have made a lot of improvements based on previous comments, and they have produced a study that is interesting for the scientific community.
In this study, the authors find that marine heatwaves (MHWs) are stronger (and more realistic) at high resolution (HR) compared to low resolution (LR), which increases sea-ice melting and solar heat input. This results in larger Arctic Ocean warming at HR. They identify a potential positive feedback between MHWs and Arctic Ocean warming. The authors emphasize the importance of using HR climate models to capture the current and future changes in the Arctic Ocean.
In my latest review, I was mainly concerned by the difficulty to visualize the statistically significant grid points in Fig. 3. This comment is still not resolved as it is not clear at all what are the regions of statistical significance in this figure. The same kind of contour line as in Fig. 4 should be used in Fig. 3.
I have a couple of additional comments below, which would need to be resolved before potential publication.
2. Specific comments
- There should be a tab space between the end of sentences and the references in brackets.
- At the end of Section 1, a brief introduction to the different sections of the paper is missing.
- Sections 2.1 and 2.3: the information about the data temporal resolution is missing.
- Section 2.7 has the same title as Section 2.6; this should be revised.
- L203-205: twice “causal influence” in the same sentence → please avoid redundancy.
- L264-266: “Since Arctic amplification…” → this sentence is not clear and not very well written, I advise the authors to re-write it.
- L279-280: I do not agree with this statement, there are many studies about climate extremes. Please remove this sentence or rephrase.
- Most figures captions: capital letters for all panels should be replaced by small letters (e.g. “(a)” instead of “(A)”), as small letters are used for the different panels.
- Fig. 1c-d: the unit (W/m²) for the spatial distribution of anomalous incoming solar radiation is missing.
- Fig. 2 caption: Replace by “at the grid points denoted by green dots in (a-b)”.
- Fig. 4 caption: typo → “contourss”.
- Fig. S1: the labels in the caption should be “c-g” instead of “d-h”.