the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Mar 2026
Paleoenvironmental and paleoclimatic reconstruction in the Western Mediterranean during the Late Early Pleistocene
Abstract. The major climate change recorded during the Early-Middle Pleistocene Transition (1.4–0.4 Ma) is characterized by an increase in the length of climatic cycles from 41 ka to 100 ka. During this period, the Mediterranean climate underwent aridification associated with a drop in temperatures. This period also corresponds to the arrival of the first hominins in Western Europe. This study aims to establish the climatic framework at the end of the Early Pleistocene between MIS 37–31 (∼1.25 to 1.06 Ma). To this end, a multiproxy approach was applied to assemblages of planktonic foraminifera, pollen and clay mineralogy, constituting a multi-method approach to climate reconstruction. Comparisons with other sequences from the Central and Western Mediterranean show major differences between the Iberian Peninsula and southern Italy. Clay mineralogy analysis highlights a sudden change in oceanic and atmospheric circulation in the Alboran Basin around 1140 ka. Climate reconstructions follow climatic cycles, with temperatures that appear to be underestimated compared to temperature reconstructions based on fauna from southern Spain. Precipitation reconstructions, on the other hand, are more consistent, suggesting that the climate and vegetation of this region are more likely to be influenced by variations in precipitation. These new data enhance our understanding of the climate of the South-western Mediterranean at the beginning of the Early-Middle Pleistocene Transition.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Climate of the Past.
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-2026-1342', Anonymous Referee #1, 01 May 2026
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RC2: 'Comment on egusphere-2026-1342', Timme H. Donders, 03 May 2026
My review of Catrain et al., "Paleoenvironmental and paleoclimatic reconstruction in the Western Mediterranean during the Late Early Pleistocene". This paper is a good multiproxy data and site comparison and is potentially a valid contribution that fits well in the CotP scope. However, there are a number or errors and missed opportunities that need to be resolved before publication. The research focus can be specified better (see below) and there is more clarity needed on what analyses have already been published and what not. For me and other readers the introduction should give a little more background into what method has what scope in general terms before providing the technical details in the methods. The language is mostly clear and the figures are well made.
The title suggestion can be a bit more attractive, e.g. Temperature and precipitation gradients in the Western Mediterranean during the Late Early Pleistocene. I have read the manuscript with attention to the overal resarch questions and approach, and palynology specifically. The X-ray methodology is not my background and so I have assumed methods to be up to standards.
The introduction addresses and interesting topic revolving around the intensification of glacials and mentions many important connected impacts, like the various driving factors in the EMPT discussion, and rightly addresses aridity as an important signal. However the manuscript fails to define a clear research focus for the paper. Yes multiproxy is important but what aspect of the climate system is addressed? This is unclear; is there reason to believe the aridity signal is misinterpreted or is the scale unknown? How does that relate to the orbital and atmospheric circulation drivers? The general problem and data scarcity are well laid out but the actual climatic problem needs sharpening.
In the introduction the (lines 899/90 the study does not make clear what data are new and what are based on earlier study (a few references are given but not very explicit). The pollen data for example are based on earlier work (Catrein et al, 2025) but it is presented in this paper as if it was new work, which is confusing.
The 3rd aim of methodological discussion of pollen-based climate reconstruction methods seems out of place as a focus, and would require a more in-depth methodological focus while here a multiproxy comparison is the key, as well as regional offsets. A thorough methodological discussion would require a different set up.
Regarding the transfer function approaches; the CAM method is specified only at the end of the method and should move up. Regardless of the approach, all methods have to deal with the non-analogue problems on these timescales as well as the presence of relict taxa outside the calibration range, and the suitability of marine data vs predominantly terrestrial calibration samples. While a multi-method is in principle good, not all these methods can handle non-analogue problems equally well. The methods are not interchangeable and some, like MAT, are particularly weak in non-analogue conditions. This requires more critical discussion in the methods section and prioritization of the (potentially) best suited methods based on e.g. Salonen et al, 2012;2019. (B)RT for example are statistical tools not grounded in ecological theory, although they perform well at the margins of the calibration range.
Regarding the MAT results, also for the foram assemblages, I would also expect to see the nearest analogue distance reported.
The reporting of the climate results for method and per MIS is not adding much. It would be more useful to discuss in terms of mean-method offsets and trends over MIS stages. This listing of numbers is not helping the reader. Better organize along point like are the offsets the same in glacial and interglacial stages?
Table 1 is incorrectly labeled as Pearson correlation coefficient, which would be r., R2 is the coefficient of determination, which is fundamentally different (I assume the R2 has actually been calculated, please check!). Also, do these (R2 and RMSE) represent values based on bootstrapping or leave-one-out validations as is common? The RMSE should be accompanied by the % of the climate calibration range and max bias, which are not given. Also the number of WAPLS components is not provided, not the evaluation plots (obs vs predicted) to assess this and the other methods. This is a shortcoming of the paper and needs improvement.
The PERMANOVA tests are poorly explained (what are you testing?) and more suitable to the assemblage data itself rather than the derived climate variables; If anything, an ANCOVA approach would be more suitable here applied per MIS. In the current approach, pretending that the PERMANOVA tests are n.s. is not the same as stating that all methods are giving similar results which is clearly not the case. Since the test is not suitable the conclusions on this point are not valid. The variability between reconstruction methods is clearly different as one can see in a single glance in Fig. 5, as is the amplitude of the signals. So likely the test is not well defined (or chosen) to detect that. Is the centroid value for each MIS? Are the ranges normalized? Since the variability then might be similar but the absolute values clearly are not. For example, the RF and BRT range do not overlap at all and therefore cannot be the same. On a more fundamental level, it is highly unlikely that the marine SST changes have a higher amplitude than the terrestrial changes (as seem from fig. 8) given the thermal inertia of ocean water.
In summary, there are some important issues to resolve regarding data source, reporting of the data, the calibration data properties. The suitability of a transported marine assemblage relatively far from shore for surface based calibration methods is not mentioned at all, while the low diversity data suggest important taxa selections happened that likely bias the reconstruction results. There is no link made between the clay mineralogy data and the potential source of the pollen, that could bias the ODP 976 data relative to the other sites. There is also no statement on sharing of data in online repositories (e.g. Neotoma, pangaea) which can be considered standard. This is a missed opportunity. Since the basic data are good I recommend a thorough re-think of some of the assumptions, the statistical tests, suitability/differentiation of the various reconstruction methods, and the research focus of the paper in the introduction. The result with the MIS 31 as not the main warm interval is surely of importance and can be more prominent.
Minor comments
L.41: important to specficy some key feedbacks, such as ice dynamics, CO2, regolith etc
L.52 the start of the EMPT ..
L54/55 what archaeological evidence? No reference here or substantiation, neither for the subsequent statement on climate sensitivity
L59 …aridification in the Mediterranean was a major parameter..
L 70 ‘as support for climate reconstruction’ do the authors mean that only these have yielded quantitative climate reconstructions? Or that there are pollenrecords at all with paleoclimate significance. The lake Ohird and Tenaghi Phillipon sites of course also fall in the latter category.
L74/75 specify time windows
L.87 This study provides
L 91 ‘pollen data to reconstruct mean air temperature and precipitation’ integrate this section with the first mentioning of pollen data in L. 89
L.93/94 What is a ‘ sea-contintent enrvironmental and climate outline’? Do you mean a Coupled marine-continental climate reconstruction?
L.96 again authors mention a comparison between central and western med; but they do not explain why this coimparison is useful or expected to carry a different climatic signal
L.148 HF (70%) and HCL (37%) digestion/treatment. What sieving was used, if at all? If this method however refrers to ealier work already published there is no need to report palynological methods here.
L.149 is the minimum grains and taxa count an aim or result of e.g. counting one slide?
- 161 How was foraminiferal preservation? Any signs of diagenesis?
L 207 “MAT … foraminifera” this phrase in not completed
L222 and following. It is not clear whether the list of biomes are the ones excluded or included.
- 240 Indicate the aim fo the PERMANOVA analysis at the start of this paragraph
- 308 .. a general mean alue of around 10oC…
L.364, “…the methods are adequate” in what way are they, in that they don’t differ in mean value? In mean values they might not but the variability is strongly different
L.400 this quantitative terms this conclusion is only supported by the MAT reconstruction, which should be mentioned (while I agree regarding the assemblage data).
- 452 “lesser influence” lesser than what?
L.455 this sentence on T. quinqueloba shoud be moved up to 451
- 466-469 this section belongs in the methods and not repeated here
Fig. 9 please indicate modern day value reference lines or points
Citation: https://doi.org/10.5194/egusphere-2026-1342-RC2 -
EC1: 'Comment on egusphere-2026-1342 by Antje Voelker', Antje Voelker, 12 May 2026
Dear authors,
since the first reviewer already brought up the issue with planktonic foraminifera assemblage based SST being too cold during some periods, I am posting this information already as an open comment and not only in my response as editor.
The too cold SST are driven by the presence of N. pachyderma that during that time period has not yet fully developed as a dominantly polar variant. We encountered the same issue at IODP Site U1387 in the Gulf of Cadiz and this has been discussed in:
Mega, A., T. Rodrigues, E. Salgueiro, M. Padilha, H. Kuhnert, and A. H. L. Voelker (2025), The Early–Middle Pleistocene Transition in the Gulf of Cadiz (NE Atlantic) – an interplay between subtropical gyre and extremely cold surface waters, Clim. Past, 21(5), 919–939, doi: 10.5194/cp-21-919-2025.
and to a lesser extent in Trotta, S., M. Duque-Castaño, T. Rodrigues, A. H. L. Voelker, P. Maiorano, B. Balestra, J.-A. Flores, A. Siniscalchi, M. Addante, and M. Marino (2025), High-frequency glacial climate instability during the Early Pleistocene: Insights from IODP site U1387 (Gulf of Cadiz), Palaeogeography, Palaeoclimatology, Palaeoecology, 674, 113041, doi: https://doi.org/10.1016/j.palaeo.2025.113041.
For the Mediterranean Sea, there is also the publication by Serrano, F., and A. Guerra-Merchán (2012), Sea-surface temperature for left-coiling Neogloboquadrina populations inhabiting the westernmost Mediterranean in the middle Pleistocene and the Pleistocene-Pliocene transition, Geobios, 45(2), 231–240, doi: https://doi.org/10.1016/j.geobios.2011.04.003.
So, in general, planktonic foraminifera SST reconstructions prior to 1 Ma in the mid-latitudes will have a "cold" bias and should be used with great caution.
Antje Voelker
Citation: https://doi.org/10.5194/egusphere-2026-1342-EC1
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The manuscript title “Paleoenvironmental and paleoclimatic reconstruction in the Western Mediterranean during the Late Early Pleistocene” by Catrain et al. is a nice paleoenvironmental reconstruction from ~1.25 to 1.06 Ma in the westernmost Mediterranean region, a key region for climate and human evolution. The study is based in the well know marine record ODP 976 located in the South Iberian margin. Authors used a multiproxy approach (planktonic foraminifera, pollen and clay mineralogy) to reconstruct past climate conditions. The data obtained have been compared with other pollen sequences from records throughout the Mediterranean and with climate reconstructions from various paleontological sites in southern Spain. The results obtained and these comparisons have led them to conclude that temperature reconstructions based on pollen from marine core 976 yield cooler temperatures than expected, and that there was a significant temperature gradient across the Mediterranean during MIS 31. The data obtained from clay minerals have been interpreted as indicators of source areas (Saharan and Sahel).
This study is closely related to a previous study by nearly the same authors that was recently published (Catrain et al., 2025 Vegetation and climate dynamics in the south-western mediterranean during MIS 37–31 (~1.25 - ~1. 06 Ma): Insights from the marine core ODP site 976 in Quaternary Science Reviews). Since the pollen database were already published and interpreted in that earlier study, this new paper is less relevant in terms of the new data it provides; however, it remains original overall because it presents new approaches and conclusions.
This is a very interesting and comprehensive piece of work; however, I can only recommend its publication after major revisions for the following reasons:
Clay mineralogy: The authors indicate that: The error on measurement reproducibility is estimated to be ±5% for each clay mineral. (Line 187). Based on the methodology they have used and the significant issue posed by the preferential orientation of the clays, I believe this error range is optimistic; but even if we accept it as valid, the data obtained should reflect that error. The authors correctly represent the error range in the figures, but in the data, the values should be multiples of 5; I believe this would bring them closer to reality and make the limitations of the data more clearly. I think that indicate contents for palygorskite (~7%), kaolinite (~17%) or chlorite (~17%), should be changed to palygorskite (~5%), kaolinite (~15%) or chlorite (~15%) or (5% ±5), kaolinite (~15% ±5) or chlorite (~15% ±5). Based on this observation, I believe that distinguishing VI phases based on the signal from the clay minerals is an overinterpretation of the data (Line 285 indicate five main phases, but VI described, typo?). If error bars were placed around each data point, as was done with the temperature reconstructions, there would be two periods: one before middle MIS 34 (low Smectite) and one after MIS 34 (High Smectite). Defining period VI with a single point may not be ideal.
I/K ratio used to retrace aeolian supplies and Smectite variations as oceanic advention proxy. I find that the evidence provided by the authors does not support this interpretation. At least since the Zanclian (Juan et al., 2020 Marine Geology), the Alboran Sea has been influenced by deep-sea currents that shape sedimentary formations, undoubtedly affecting the clay minerals that enter the basin and possibly also the types of pollen. Site 976 is located in a plastered drift that is sensitive to variations in the ocean currents flowing through the western Mediterranean (e.g., LIW or WMDW), which have changed over time. Given the current state of knowledge, I do not believe it is acceptable to assume that the water column is transparent to detrital or pollen input. Eolian input is also transported to the ocean by the rivers in the present day Iberian margin (Camperrós et al., 2026 EPSL), changing the original proportions of the source clay areas (e.g., Sahel or Sahara). It should also be noted that hemipelagic sediments could be enriched to 60% in eolian input but in conturites (sediment drifts) when sedimentation rates are high, the eolian input becomes diluted and is therefore impossible to distinguish in the marine sediment, and site 976 has high sedimentation rates.
Comparisons between hemipelagic sediments and contourites along the Iberian margin make it clear that heavy mineral and clay minerals (represented by elements such as K (illites)) undergo processes of focusing or advection when the intensity of bottom currents changes (e.g., Bahr et al., 2014 Geochemistry, Geophysics, Geosystems). Changes in current intensity also cause significant changes in sedimentation rates, a phenomenon observed in core 976 during the period under study but for which no explanation is provided. Changes in sea level also cause alterations in the deep-sea sediments of the Iberian margin (de Castro et al., 2021 Sedimentology); specifically, lowering/rising sea levels capture/carry away sediments from the continental shelf, which could account for the variation observed in the clay minerals known as Phase II, during transition periods.
Another possible explanation is that the increased influx of smectites may be due to greater soil erosion on the continent as a result of increased aridity and cooling in the region, and that the change in the I/K ratio may be due to a greater intensification of bottom currents as the climate becomes colder. It is undoubtedly difficult for the authors to know exactly what is happening (whether the currents are stronger, whether more river input, whether the sources of soils or wind-blown material are changing, etc.), but they should make it clear in the manuscript that there may be other factors not considered in this manuscript version could affect the record interpretation.
Pollen record: Can we rule out the possibility that variations in bottom currents do not affect pollen content? If the eolian material is primarily of North Africa origin and the riverine input is of Iberian origin, couldn’t this introduce a bias in the interpretation of the pollen record, given that some pollen grains are primarily dispersed by the wind while others are not?
The site ODP 976 precipitation and temperature shows marked changes with other near records (Palominas or Monte San Giorgo). It could be that the database being used isn't the most appropriate one? Authors also use the EAPDB database that covers Eurasia and the Mediterranean. Why do you not choose another one that covers only the Mediterranean?
Assemblages of planktonic foraminifera. Not only are pollen-based temperature reconstructions cooler than those obtained based in faunal assemblages, planktonik based SST also are significantly cooler than other records from the Iberian margin based in other proxies (e.g., alkenones). For site U1385 Oliveira et al., 2017 QSR reconstruct SST up to 20 ºC in SW Iberian margin and Temperate forest (%) shows clear correlation with STT. I find the explanation that the temperature data from Site 976 represent a regional signal that differs from the local signal (paleontological sites, Line 562) to be somewhat inaccurate, because the data from Site 976 almost always show cooler temperatures than one might expect. Could this be due to local oceanographic factors such as upwelling activity in the Alboran Sea?
I hope you find all these comments helpful for this nice study.
Typo in Line 110 Almeria Oran Front