| 22 Jun 2026
A review of Last Interglacial sea-level proxies in South Asia and the Indian Ocean
Abstract. In this work, we present a standardized database of Last Interglacial (132–80 ka) sea-level proxies across the South Asian and Indian Ocean region, including the coasts of Iran, Oman, India, the Maldives, and the Cocos (Keeling) Islands. The database stems from a critical revision of the data included in 17 peer-reviewed studies, which were standardized using the World Atlas of Last Interglacial Shorelines (WALIS), and is available as Ali et al. (2026, https://doi.org/10.5281/zenodo.18512770). A total of 54 sea-level index points were reassessed by evaluating stratigraphic context, elevation measurement techniques, depositional environments, and chronological constraints obtained from U-series, luminescence, electron spin resonance, and cosmogenic nuclide dating. The data is characterized by regional differences in the elevation of past relative sea-level proxies that are driven primarily by tectonic, dynamic topography, and glacio-hydro-isostatic forcings. On the active margins of southern Iran and northern Oman, terraces dated to Marine Isotopic Stage (MIS) 5e (125 ka), 5c (100 ka), and 5a (80 ka) were preserved at 20–60 m a.s.l., reflecting long-term uplift linked to the Zagros foreland and Makran subduction system. On the coasts of western and southern India MIS 5e relative sea-level proxies are found at 1–4 m a.s.l., more in line with low tectonic uplift. On Indian Ocean islands, such as the Maldives and Cocos (Keeling) Islands, MIS 5e reefs are now submerged at depths of 10–17 m b.s.l., indicating subsidence throughout the late Quaternary.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Earth System Science Data.
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I have read and reviewed the ESSD manuscript and associated WALIS-extracted regional dataset on Last Interglacial sea-level proxies in South Asia and the Indian Ocean, by Ali, Cerrone and Rovere.
The manuscript and the dataset that is its asset subscribes to the WALIS database format, purposely designed for this research subject: Piece by piece create regional databases, incorporating scattered published subregional record, together forming a world atlas of such data. The current paper does so for Iran, Oman, India, Maldives and Cocos Islands. The setup of the paper matches earlier (virtual special issue) contributions on WALIS databases in the ESSD journal, and as such is straight forward. The dataset draws upon 17 references published between 1989 and 2020. Three map figures and a informative longitude/tectonic regime orded Relative Sea Level plot form the figures.
I have kept annotations of minor corrections as annotations in the manuscript PDF file. Below I list what I regard non-trivial comments.
Ambivalent treatment of 'long-term' uplift in the text
This regards Line 22 (Abstract), Sections 3.1.1.x, 3.1.2.x and 3.1.3.x on series of sites along uplifting sections of Iran and Oman coast, and Section 4.1.1. (Discussion of uplift in Iran and Oman).
For some sites, the quoted long-term rates (also called VLM estimates in the database, unit m/kyr) appear based on the time 'from LIG to now' (e.g. 3.1.1.5 Lipar). For other sites, the uplift rates quoted (in text, or solely in dataset, e.g. 3.1.1.1 Haleh) it appears to have also included 'older-than LIG terraces', perhaps qualitatively only, perhaps quantitatively (pre-LIG MIS ages assigned to above-LIG preserved levels: explicit mention for 3.1.2.1 Kish Island). For yet other sites (Northern Oman) there is 'very long' uplifted setting record (twelve terraces, i.e. many terraces older than LIG). The point than becomes: how long is long in 'long-term'? For yet other site (Oman Sur Lagoon) there is no mention of uplift in the text, and a high value 'for during LIG' (op. cit. note field) entered in the VLM field. As I read it in the database note field, this would be a short-term uplift event all most, recorded during the highstand. This is a different entity than a long-term VLM rate.
I think the manuscript can be improved on this, by mentioning the differences in duration times for the uplift estimates consistently in the text (and signalled in the database note field). It is currently appropriately mentioned for some of the sites, and left ambivalent for others.
Mention of remaining geographic gaps
In line 32-34, early in the introduction, the manuscript mentions that Pakistan coast line has no records, where Iran and India have. Iran coast line is indeed reasonably covered. India coastline has long geographic gaps in it too (Fig. 1 shows). I recommend to move the remark from the Introduction to the Discussion section, and briefly mention and address also why along the India coast there are substantial data gaps. I understand this will have part access, national research tradition and such reasons, but there could also be physiographic reasons to discuss.
Detailed corrections
Oman Sur Lagoon database entry (4501, 4502, 4541): check the recorded VLM rate there
India Rameshwaram site (line 355-363): clarify the lateral/vertical facies/architecture relations between the two coral species patches
India Vettaikaraniruppu site (line 390): be neutral on calling this a highstand marker, as it may be transgression marker from before highstand.
Trivial minor corrections
See the annotated PDF attachment.
It also includes the above remarks. The uplift remarks are colour coded purple. The other remarks orange.
Best regards,
Kim Cohen, Utrecht, Netherlands.