the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 27 Aug 2026
A Comprehensive Global Ocean Radiocarbon Dataset (1700–2024) for Climate Applications
Abstract. Radiocarbon (14C) in the ocean, reported as fractionation-corrected Δ14C, is a key tracer of circulation, ventilation, and carbon-cycle exchange on decadal to centennial timescales. We present a harmonized global compilation of marine Δ14C observations spanning 1700–2024, comprising 68,543 measurements from two complementary streams: 58,216 ship-based dissolved inorganic carbon (DIC) bottle samples (1955–2024) and 10,327 biogenic carbonate measurements from corals, bivalves, gastropods, and sclerosponges (1700–2020). The ship-based component builds on the Global Ocean Data Analysis Project (GLODAP) by adding data from additional hydrographic cruises and 68 peer-reviewed studies. The carbonate records provide time-resolved observations at individual sites, including historical periods prior to direct measurements, and they extend coverage to coastal, tropical, and deeper-habitat settings where direct seawater sampling remains sparse. All records were screened for metadata completeness, transcribed into a common reporting framework following Stuiver and Polach (1977), and assigned synthesis quality flags (DELC14QC) through primary quality control. Deep-ocean crossover diagnostics are archived separately for user advisory review and do not modify bottle DELC14QC. The merged ship-based and biogenic carbonate measurements together span pre-bomb baselines through the modern bomb-14C decline across global ocean basins. Version~1.2026 of the compilation is archived on Zenodo as flat CSV files with a per-contribution source table; release in Linked Paleo Data (LiPD) format is planned. The product captures pre-industrial baselines, the bomb-14C transient and its penetration into the interior ocean, and the post-peak decline through recent decades, and is intended to support ocean ventilation assessments, Earth system model evaluation, and multi-century carbon-cycle synthesis.
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Status: final response (author comments only)
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RC1: 'Comment on essd-2026-691', Patrick Rafter, 15 Sep 2026
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RC2: 'Reply on RC1', Patrick Rafter, 16 Sep 2026
My copy and paste missed a few additional items (my "line by line" notes). I've pasted all of them below.
Line by line notes:
Line 3: “harmonized” at first struck me as an odd choice, but this word is used throughout the manuscript. If I were writing this, I would use this novel and useful description, although with a very brief (perhaps parenthetical) explanation of *exactly* what is meant.Line 15: “Is planned”. Although I fully endorse this release in the LiPD format, I find it is non-standard for manuscripts to “plan” to submit datasets. A great philosopher, long ago and perhaps far away once said “do or do not”. I think this is a massively useful compilation and entirely compatible with the ESSD format *and* I would either not mention LiPD or I would push this through in LiPD.
Line 313: A lot of discussion of LiPD and the LiPDverse. I’m confused because the text seems to suggest (?) that the data will be released in the LiPD framework... before / after acceptance in ESSD?
Line 345: I especially like this entire “crossover analysis” discussion. Very thoughtful.
Section 4.2: I am sure there are many other datasets in this compilation that can also be examined, but I think this section does a good job of using some of them as examples. I mention this because sometimes reviewers of these types of manuscripts tend to push the authors into more and more analyses… which is not always bad but I think it is unnecessary for this particular journal.
Citation: https://doi.org/10.5194/essd-2026-691-RC2 -
AC1: 'Reply on RC2', Nabir Mamnun, 25 Oct 2026
We thank Dr. Patrick Rafter for his positive and constructive review. We are glad the dataset is already in use, and we would be glad to include his unpublished and recently published datasets in a later release. We will contact him directly about this. Reviewer comments are quoted below, followed by our response. Line numbers in the headings refer to the discussion preprint.
Submission of new data
"...another thing my compilation studies failed to acknowledge is the future submission of data to the compilation. [...] If the text could explicitly state that new datasets are welcome—plus directions on submission—I think that might be useful."
Response: We agree. The invitation at the end of the preprint conclusions was too vague, and we added directions in Sect. 2.5.2 (Versioning and updates). Version 1.2026 stays as reviewed. New seawater DIC and biogenic carbonate Δ14C can be sent to ocean-delta14c@googlegroups.com or submitted as an issue at https://github.com/nmamnun/ocean-delta14c-dataset/issues, with location, depth, date or age, Δ14C and its uncertainty, δ13C where reported, a laboratory sample code, and a reference or DOI. Biogenic records should also give the archive type, taxon, and dating method. Unpublished data will be included only with the owners' agreement to release them under CC BY 4.0. They will go through the same quality control and into a later Zenodo version, with the contributors credited. The LiPDverse compilations will be updated to match that version. The conclusions still invite contributions of new data, and the Code and data availability section points to Sect. 2.5.2.
Line 3: "harmonized"
"...I would use this novel and useful description, although with a very brief (perhaps parenthetical) explanation of exactly what is meant."
Response: We agree. The abstract now says "comprehensive" instead of "harmonized". In the introduction, "harmonized" is defined as a shared reporting notation (fractionation-corrected Δ14C, Stuiver and Polach, 1977), units, column structure, metadata, and the DELC14QC flag. We did not adjust the reported Δ14C values.
Line 15: "is planned" (LiPD)
"'Is planned'. [...] I find it is non-standard for manuscripts to 'plan' to submit datasets. [...] I would either not mention LiPD or I would push this through in LiPD."
Response: We agree, and RC3 raises the same point. The LiPD compilations are on LiPDverse, and the abstract now says so. The Zenodo deposit remains the CSV files. See the reply to the major LiPD comment below.
Line 313: LiPD/LiPDverse discussion and timing
"A lot of discussion of LiPD and the LiPDverse. I'm confused because the text seems to suggest (?) that the data will be released in the LiPD framework... before / after acceptance in ESSD?"
Response: The LiPD files are available now. See the reply to the major LiPD comment below.
Line 345: crossover analysis
"I especially like this entire 'crossover analysis' discussion. Very thoughtful."
Response: Thank you. We kept the discussion and added a short explanation of the North Atlantic and Southern Ocean exclusions in Sect. 2.4.3 and Sect. 4.1. See the reply on the North Atlantic and Southern Ocean exclusions.
Section 4.2: examples
"...I think this section does a good job of using some of them as examples. [...] I think it is unnecessary for this particular journal."
Response: Thank you. We kept Sect. 4.2. The only change there is the Fig. 6 symbols. See the reply on the Figure 6 caption.
Citation: https://doi.org/10.5194/essd-2026-691-AC1
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AC1: 'Reply on RC2', Nabir Mamnun, 25 Oct 2026
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RC2: 'Reply on RC1', Patrick Rafter, 16 Sep 2026
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RC3: 'Comment on essd-2026-691', Siv K Lauvset, 30 Sep 2026
The paper presents a new compilation of ocean radiocarbon data which is considerably more comprehensive than previously available data compilations. The authors have done a thorough job of mining, compiling and quality controlling data from different sources. This data product will be incredibly useful for many purposes in ocean science. The manuscript is remarkably well-written (though in my mind with far too many semicolons), the illustrations are clear and detailed, and the information given is detailed and comprehensive. The manuscript does a very good job of describing the data and the data files themselves are nicely structured and intuitive to use. I have one issue I would like the authors to change and a few minor comments (detailed below), but the manuscript can be published after these minor revisions. I also recommend that the authors contact the GLODAP team when the paper is published and we’ll help promote it using the www.glodap.info website.
Major issue (sort of):
The authors repeatedly mention and describe a version of the data (in LiPD-format) that does not yet exist. This is not appropriate for ESSD where all data should be available for the reviewers and the readers. The readers are supposed to be able to access the data using the paper, and the paper can and should be used as a citation for the data. But that does not work in this case when the readers will not be able to access all data versions using this paper. Also, the paper will not age well since a lot of important information will be quickly outdated. That means that the paper will not get many citations. I understand the desire to publish the data product in LiPD-format. I recommend that the authors complete this version of the data and make it available during revision of this manuscript. Then the relevant text can be changed to describe an existing version. The data availability should also be updated accordingly.
If the authors are unable to complete the LiPD-version during revision then the text describing this version needs to be removed from the manuscript. The authors can instead add a brief “future work/plans” section to mention this planned update. But the update itself would then need to be published in a new paper (perhaps as part of a living data process).
Minor comments:
Line 14-15: Either publish the LiPD-version or remove this information
Line 46: I think that here it is more appropriate to cite Key et al. (2004), Olsen et al. (2016) and Lange et al. (2026) for GLODAP versions 1, 2, and 3 respectively. Lauvset et al. (2024) is cited when GLODAPv2.2023 is mentioned.
Line 137: I believe Swift and Diggs (2008) is a better reference to use for the WOCE exchange format.
Swift, J. and Diggs, S. C.: Description of WHP exchange format for CTD/Hydrographic data, CLIVAR and Carbon Hydrographic Data Office, UCSD Scripps Institution of oceanography, San Diego, CA, US, https://cchdo.github.io/hdo-assets/documentation/WHP_Exchange_Description.pdf (last access: 29 April 2024), 2008.
Line 191: The section referred to in parenthesis is called “Data and Code Availability”. Please correct.
Line 213-223: See major comment. Please update to describe an existing and available version of the data, or remove.
Line 233: Remove mention of LiPD unless the available data product is updated.
Line 239-240: As a matter of curiosity: are the authors planning a living data process in ESSD for this data product and future versions?
Table 2: See major comment. An ESSD paper should describe that that exist and are available to the reader. This table also presents planned versions which I find inappropriate.
Line 348-350: Please add a few words to elaborate on why the North Atlantic and Southern Ocean pairs are excluded. I know it is mentioned elsewhere but it bears repeating here.
Figure 6 caption: It is difficult to see the difference between the crimson and purple stars (both reading on paper and on screen). Please change to colors with more contrast, or use different markers.
Line 436-438: The sentence after the semicolon is incomplete so the use of semicolon is incorrect. The sentences are also difficult to understand as it is not obvious how Druffel et al (2017) relates to the Arctic data. Please revise for clarity.
Line 458-462: See major comment. The Code and Data Availability section should only present data that are actually available. The LiPD-version is not.
Line 465-466: I recommend the authors add a brief “future plans” section for information such as this.
Citation: https://doi.org/10.5194/essd-2026-691-RC3 -
AC2: 'Reply on RC3', Nabir Mamnun, 25 Oct 2026
We thank Dr. Siv Lauvset for her careful and helpful review and her recommendation of minor revisions. We gladly accept the offer to promote the dataset through www.glodap.info and will contact the GLODAP team once the paper is published. Reviewer comments are quoted below, followed by our response. Line numbers in the headings refer to the discussion preprint.General: semicolons"The manuscript is remarkably well-written (though in my mind with far too many semicolons)..."Response: Thank you. We reduced a few semicolons in the running text, including in the quality-control and crossover sections.Major issue: LiPD version that does not yet exist"The authors repeatedly mention and describe a version of the data (in LiPD-format) that does not yet exist. [...] I recommend that the authors complete this version of the data and make it available during revision of this manuscript. [...] If the authors are unable to complete the LiPD-version during revision then the text describing this version needs to be removed from the manuscript. The authors can instead add a brief 'future work/plans' section..."Response: We agree. The LiPD files were completed during revision and are on LiPDverse as two compilations: GlobalOceanDelta14C for biogenic carbonate (https://lipdverse.org/GlobalOceanDelta14C/) and GlobalOceanDelta14C-Seawater for ship-based DIC (https://lipdverse.org/GlobalOceanDelta14C-Seawater/). They carry the same Δ14C values, uncertainties, and DELC14QC flags as the Zenodo CSV files. They do not have a separate DOI, so users should cite this paper. We did not add a Future plans section.The abstract now points to LiPDverse. In Sect. 2.5.1 (File organization) we shortened the LiPD description and named the two compilations. In Sect. 2.5.2, only the Zenodo files are described as having a persistent DOI, and the LiPDverse compilations are described as versioned. The dataset overview (Sect. 3) names the two compilations. Table 2 no longer lists a planned product: it has one row for each compilation, and the note says they are on LiPDverse and not in the Zenodo bundle. The Code and data availability section gives the same two links.L14–15"Either publish the LiPD-version or remove this information"Response: Same as the reply to the major LiPD comment. The abstract no longer says that a LiPD release is planned.L46: GLODAP citations"...it is more appropriate to cite Key et al. (2004), Olsen et al. (2016) and Lange et al. (2026) for GLODAP versions 1, 2, and 3 respectively. Lauvset et al. (2024) is cited when GLODAPv2.2023 is mentioned."Response: We agree. The GLODAP citation in the introduction is now Key et al. (2004), Olsen et al. (2016), and Lange et al. (2026) for the GLODAPv3 description (https://doi.org/10.5194/essd-2026-496). Where the methods name GLODAPv3 (Sect. 2.2), we also cite the data product (https://doi.org/10.25921/m6tp-mj50). Lauvset et al. (2024) is cited only for GLODAPv2.2023.L137: WOCE exchange format reference"I believe Swift and Diggs (2008) is a better reference to use for the WOCE exchange format."Response: We agree, and thank you for the reference. The WOCE Exchange format is now cited as Swift and Diggs (2008) in Sect. 2.4.1. Key et al. (2004) remains the citation for GLODAP (v 1).Swift, J. H. and Diggs, S. C.: Description of WHP exchange format for CTD/Hydrographic data, CLIVAR and Carbon Hydrographic Data Office, UCSD Scripps Institution of Oceanography, San Diego, CA, USA, https://cchdo.github.io/hdo-assets/documentation/WHP_Exchange_Description.pdf (last access: 1 October 2026), 2008.L191: section name"The section referred to in parenthesis is called 'Data and Code Availability'. Please correct."Response: Thank you. The ESSD heading is "Code and data availability". The cross-reference in Sect. 2.4.3 now uses that name.L213–223"Please update to describe an existing and available version of the data, or remove."Response: Same as the reply to the major LiPD comment. The revised paragraph is in Sect. 2.5.1.L233"Remove mention of LiPD unless the available data product is updated."Response: Same as the reply to the major LiPD comment. The persistent DOI is for the Zenodo files, and the LiPDverse compilations are described as versioned without that DOI (Sect. 2.5.2).L239–240: living data process"As a matter of curiosity: are the authors planning a living data process in ESSD for this data product and future versions?"Response: No. Version 1.2026 stays fixed. Later measurements will be new Zenodo versions with new DOIs. If a later update is large enough for a living-data paper or a short follow-up, we will say so when that update exists. The versioning text in Sect. 2.5.2 describes this and does not mention a living-data process.Table 2"An ESSD paper should describe [data] that exist and are available to the reader. This table also presents planned versions which I find inappropriate."Response: We agree. See the reply to the major LiPD comment. Table 2 now lists the two LiPDverse compilations that exist.L348–350: exclusion of North Atlantic and Southern Ocean pairs"Please add a few words to elaborate on why the North Atlantic and Southern Ocean pairs are excluded."Response: We agree. North Atlantic pairs are left out of the baseline because bomb 14C is still entering North Atlantic Deep Water below 1500 m, so the offsets mix real change with measurement differences (Lester et al., 2024). Southern Ocean pairs south of 40°S are left out because Δ14C below 1500 m cannot be assumed steady where deep water is formed and exported. The low, nearly uniform Southern Ocean values are not evidence that nothing has changed. Both sets remain in the archived crossover table. The 178 pairs used for the baseline (3,131 depth levels, 56 cruise combinations) are in the Pacific and the subtropical and tropical Indian Ocean. This is explained in Sect. 4.1, with a shorter version in Sect. 2.4.3.Figure 6 caption: crimson vs purple stars"It is difficult to see the difference between the crimson and purple stars [...]. Please change to colors with more contrast, or use different markers."Response: We agree. Purple is already used for Guilderson and Schrag (1998) in panel a. In panel b, visual-inspection flags (DELC14QC = 10) are filled black stars, and inter-profile flags are open black diamonds. The caption matches the figure.L436–438: incomplete clause, Druffel et al. (2017)"The sentence after the semicolon is incomplete [...] it is not obvious how Druffel et al (2017) relates to the Arctic data. Please revise for clarity."Response: We agree. Of the 115 shallow 2010s Arctic bottles (depth ≤ 50 m, north of 66.5°N, DELC14QC = 2), only four are from Druffel et al. (2017), but those four are the ends of the range: about −35‰ in the Chukchi/Beaufort sector (USCGC Healy 2012, 21 m) and about 50‰ in the Eurasian Arctic (R/V Oden 2012, 20 m). Both are dissolved inorganic carbon. The revised text in Sect. 4.3 says this, and the semicolon is gone.L458–462: Code and data availability"The Code and Data Availability section should only present data that are actually available. The LiPD-version is not."Response: We agree. See the reply to the major LiPD comment. That section now gives the two LiPDverse links. The LiPD files have no separate DOI.L465–466: future plans"I recommend the authors add a brief 'future plans' section for information such as this."Response: That sentence described a future software deposit. That deposit already exists, so we removed the sentence and cited it (https://doi.org/10.5281/zenodo.22100626). We did not add a Future plans section. New data are described in Sect. 2.5.2, and the LiPD compilations are described where they are available (see the reply to the major LiPD comment).Citation: https://doi.org/
10.5194/essd-2026-691-AC2
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AC2: 'Reply on RC3', Nabir Mamnun, 25 Oct 2026
Data sets
A Global Ocean Radiocarbon (Δ¹⁴C) Dataset (1700–2023) from Dissolved Inorganic Carbon and Marine Carbonate Archives Mamnun et al. https://zenodo.org/records/18674659
Model code and software
v1.0: Compilation code for a global ocean radiocarbon (Δ¹⁴C) dataset (1700–2024) Nabir Mamnun https://zenodo.org/records/22100626
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Manuscript “A Comprehensive Global Ocean Radiocarbon Dataset (1700–2024)
for Climate Applications,” as reviewed by Patrick Rafter
Summary
Careful and thoughtful compilation studies like this manuscript discusses are essential if we are to “level up” ocean, climate, and carbon cycle research. The authors here have done an outstanding job and I have taken notes on how I could have improved my own compilation work. I am very much looking forward to working with this dataset, which I have already downloaded and quickly looked over.
All in all, this manuscript is the coolest study I’ve reviewed this year—maybe for the past few years. I have very few notes while reading, which speaks to a careful crafting of the manuscript. I thank the authors for this.
I am also happy to see a static / persistent DOI. (I am unsure I was able to do this with any of my earlier geochemical compilations.) Speaking of which, another thing my compilation studies failed to acknowledge is the future *submission* of data to the compilation. This is especially relevant for this study because I have several very useful (either unpublished or recently published) datasets that I would like to contribute to this compilation. If the text could explicitly state that new datasets are welcome—plus directions on submission—I think that might be useful.
Line by line notes:
Line 3: “harmonized” at first struck me as an odd choice, but this word is used throughout the manuscript. If I were writing this