Continental archives (speleothems, lake & river sediments, peatlands, vertebrate & invertebrate remains) are often highly temporally resolved (sub-decadal to seasonal) & provide more direct information about atmospheric& hydrological processes than marine archives. The variety of continental archives allows for intercomparison of results from different settings, while multi-proxy records from the same archive disentangle local & supra-regional environmental conditions. This approach is most useful when dealing with high spatial variability, signal buffering, nonlinearities & uncertainties in the proxy sensitivity.
This session aims to highlight recent advances in the use of innovative & quantitative proxies to reconstruct past environmental change on land & to encourage bringing palaeoecological data into the public domain. We join forces with COST action CA23116 - Open Palaeoecological Data (PalaeOpen) collating different proxy data relevant for nature conservation & attempting to make them publicly available. The action is organised with working groups focusing on: terrestrial & aquatic proxies; infrastructure & databases; & outreach & education.
We welcome studies of all continental archives, e.g., carbonates (cave deposits, palaeosols, snails), sediments (lakes, peatlands, rivers, alluvial fans), & biological materials (tree rings, fossil assemblages, bones, biomarkers). We are keen on reconstructions of temperature & hydrologic variability, palaeoclimate data assimilation, monitoring & modelling studies leading to calibration or simply better understanding of climate proxies & to learn about limitations, failed approaches & negative results.
Our session provides a forum for discussing recent innovations & future directions in continental palaeoenvironmental studies & integrated analyses of continental ecosystem responses to natural & anthropogenic environmental change.
Orals: Tue, 5 May, 08:30–10:15 | Room 0.96/97
The Holocene (last 11,700 years to pre-industrial) epoch offers a critical test bed for assessing natural temperature variability and benchmarking anthropogenic climate change. By leveraging TEX86 measurements (n=31) of speleothems from two caves ~400 km apart, we present the first 12,000-year quantitative regional temperature reconstruction for Mainland Southeast Asia (MSEA), a critical hydroclimatic region influenced by Indian and East Asian monsoon systems. Our speleothem TEX86 record reveals pronounced centennial- to millennial-scale temperature fluctuations throughout the Holocene, including an abrupt ~4 °C cooling during the mid-to-late Holocene transition. This contrasts with a suite of transient climate model simulations (CESM-1.2 3 Ma simulation, MPI-ESM andTRACE-21K-II), which show monotonic warming across the same interval, failing to reproduce internal variability. We then compared our proxy record with outputs from a suite of Global Climate Model equilibrium sensitivity simulations, in most of which dust–vegetation–albedo feedback in northern Africa is included, a feature missing in earlier models. Results show better agreement of thesemodels with the observed temperature changes in MSEA. We hypothesize that the Indian Ocean Dipole (IOD) might play an important role in driving the observed temperature variations, a notion supported by both sensitivity simulations and sea surface temperature proxy records. Cooling of the eastern Indian Ocean (i.e. positive IOD-state) may induce regional megadroughtconditions, potentially leading to widespread declines in C₃ vegetation over MSEA. These land surface changes likely enhanced surface albedo, and, in combination with reduced downwelling longwave radiation due to lower atmospheric water vapor, contributed to a net cooling effect. Our results underscore the need to improve the representation of hydroclimate–vegetation feedback in climate models to better capture regional climate dynamics and enhance model skill for both past climate reconstruction and future projections.
How to cite: Basu, S., Patterson, E., Griffiths, M. L., Martínez-Gracía, A., Johnson, K. R., Timmermann, A., McGee, D., Wolf, A., Schmitt, M., Henderson, G. M., and Wassenburg, J. A.: Hydroclimate-vegetation feedbacks drive Holocene temperature variability in Southeast Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17604, 2026.
The lithium isotopic composition (𝛿7Li) of dripwater from which speleothems precipitate is hypothesised to be determined by local changes in weathering congruency in the epikarst: the ratio of primary mineral dissolution to secondary mineral formation. Therefore, speleothem 𝛿7Li records may provide an avenue to determine past changes in local terrestrial silicate weathering processes and/or intensity, a key feedback mechanism for removing atmospheric CO2 over millennial to million-year-timescales. However, these records are complex to interpret due to persistent uncertainty in the relative importance of hydrology and weathering congruency in controlling fluid 𝛿7Li values. By evaluating three overlapping speleothem 𝛿7Li records spanning 12.3 – 0.5 ka from Lancaster Hole, Yorkshire Dales, U.K., and comparing them with new and existing 𝛿13C, 𝛿18O, Mg/Ca, and Sr/Ca records from the same samples, we have developed a framework for interpreting 𝛿7Li in speleothems.
Both hydrology and weathering congruency affect speleothem 𝛿7Li records from the Yorkshire Dales. From correlated and elevated 𝛿7Li, 𝛿13C, Mg/Ca, and Sr/Ca records we infer increased epikarst residence times, usually driven by decreased effective infiltration above the cave. This scenario is characterised by increased prior carbonate precipitation, decreased drip rates, and prolonged water-rock interaction times, supporting a hydrological control on Li isotope ratios. However, on millennial timescales our 𝛿7Li records do not replicate across speleothems, indicating that water residence times in the epikarst can be highly localised due to different flow path lengths. In addition, the hydrologically-controlled correlation between 𝛿7Li and 𝛿13C, Mg/Ca, and Sr/Ca records is not consistent for the entire records from the Yorkshire Dales. An excursion to low 𝛿7Li values coupled with elevated Mg/Ca, Sr/Ca, and 𝛿13C values is observed prior to 11 ka, immediately after the Younger Dryas. This might indicate that regional changes in weathering congruency, driven by decreased surface vegetation, increased supply of primary silicates, and high denudation rates following the Younger Dryas, can override the local hydrological control on speleothem 𝛿7Li values.
We apply this framework to help interpret two new 𝛿7Li speleothem datasets: i) a series of Siberian speleothems spanning interglacials MIS 9 – 15, and ii) a flowstone record from Buffalo Cave, South Africa, spanning 1.5 – 1.7 Ma. We discuss these datasets and investigate how fluid residence times and weathering congruency fluctuate over interglacials in permafrost and savannah terrains.
How to cite: Brown, K., Wright, L., Atkinson, T., Hopley, P., Pogge von Strandmann, P., Vaks, A., F. M. Breitenbach, S., Umbo, S., Margerum, J., and Wilson, D.: A framework for interpreting Li isotopes in speleothems using records from the U.K., Siberia, and South Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14800, 2026.
Soil organic carbon (SOC) sequestration is widely promoted as a nature-based climate solution, but whether soils will continue to act as a net carbon sink depends on the future sensitivity of SOC to ongoing environmental changes. Studies show that a large fraction of SOC is chemically or physically associated with minerals. In addition, minerals provide essential nutrients (e.g. K+, Ca2+, Mg2+). Soil mineral properties, such as exchangeable base and acid cations and cation exchange capacity (CEC) change on millennial timescales and as a response to climate change. The impact of climate change on mineral-mediated SOC stabilization and mineral fertility parameters remains poorly understood because there is no method to directly quantify soil mineral fertility changes through time in paleosol archives.
Recent work on branched glycerol dialkyl glycerol tetraethers (brGDGTs), biomarker lipids that record past environmental changes, indicates that their distribution is influenced by concentrations (cmolc/kg) of mineral fertility properties (exchangeable Ca²⁺, Mg²⁺ and the sum of base cations). In this study we a) quantify how soil mineral fertility controls GDGT distributions in central African soils, b) develop and calibrate GDGT-based proxy ratios for soil mineral fertility for this region, and c) apply the proxy to a geological record.
To capture a large soil geochemical and climatic gradient in our dataset for proxy calibration, we selected 69 sites (topsoils) across tropical forests and savannah grasslands in central Africa that span different parent bedrocks, mean annual air temperatures (6-30°C) and precipitation regimes (580-2800 mm/yr) with contrasting soil pH (2.7-7.6), exchangeable basic (Ca²⁺, Mg²⁺) and acid cation (Al3+, Fe2+) concentration values. Exchangeable base cations, CEC and summed bases co-varied strongly with fractional abundance of specific brGDGTs in soils with medium (4.5<pH<6.5) to high pH (pH>6.5) soils. Multivariate analyses show that exchangeable Ca²⁺ and Mg²⁺, together with mean monthly potential evapotranspiration (mm) and mean annual precipitation (mm), explain a significant variance in brGDGT composition in the dataset. Based on these empirical relationships, we derived a novel proxy that correlates strongly with exchangeable Ca²⁺ (r = 0.94, p < 0.001) and Mg²⁺ (r = 0.85, p < 0.001). The performance and caveats of our brGDGT-derived fertility proxy for central Africa (for instance: influence of precipitation and evapotranspiration on the proxy ratio, limitations in low pH and high total organic carbon soils) will be discussed.
We then applied the proxy to a 2 m peat soil from Yangambi (Democratic Republic of the Congo), which, based on bulk 14C dating, covers two major Late Holocene Rainforest Crisis intervals (LHRC; 2500 and 4000 cal yr BP). We reconstructed soil exchangeable calcium and magnesium content (cmolc/kg) by using the calibrated proxy and found that the amount of both cation concentrations decreased between 4000 and 1900 cal yr BP. This preliminary cation concentration reconstructions for LHRC periods in Yangambi delivers new insights by comparing brGDGT signals from bulk fraction and oxidation-resistant mineral associated organic matter (MAOM) fraction.
How to cite: Mandal, A. K., Griepentrog, M., Doetterl, S., Eglinton, T. I., Magill, C. R., Winterberg, J., Lattaud, J., Rowley, M. C., Wanlin, G., Summerauer, L., and De Jonge, C.: Reconstructing soil exchangeable calcium and magnesium in central Africa (DRC) during the Late Holocene Rainforest Crisis using a new biomarker lipid tool, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19903, 2026.
Subfossil gastropod assemblages preserved in geological deposits provide valuable archives to reconstruct past environmental and climatic conditions. We present new results from loess-palaeosol sequences in the Armenian Highlands that document multiple glacial-interglacial transitions over the past ~400 ka. The primary aim of this study is to generate quantitative palaeoclimate data suitable as reference data for the calibration of Earth system models. Our approach combines stable oxygen isotope analysis (δ18O) of gastropod shells with ecological interpretation of species assemblages. The latter is based on mutual climatic range analysis, complemented by probability density function-based climatic niche modelling using modern species distribution data as reference. The composition of gastropod assemblages showed distinct variations across the sequences, indicating shifts in ecosystem characteristics and associated climatic conditions. We identified a significant relationship between specific ecological groups of gastropods and δ18Oshell values. Predominantly xerophilous assemblages linked to stadial phases showed more negative δ18Oshell signals, whereas mesophilous assemblages linked to interstadial and interglacial phases corresponded to more positive values. δ18Oshell signals reflect the isotopic composition of ingested precipitation, which in the studied region is closely linked to temperature. Transfer function-based reconstructions indicate a mean growing season temperature difference of ~4.9°C between stadial and interglacial phases. Furthermore, predictor analyses and climatic range modelling suggest, that species compositions strongly correspond to mean annual precipitation amounts. Reconstructed mean annual precipitation estimates range from ~510 mm during glacial phases to ~770 mm during interglacials. These results provide new proxy-based quantitative climate data for stadial and interglacial conditions in the Caucasus region and demonstrate the potential of gastropod shell assemblages as robust proxies for palaeoclimate reconstruction.
How to cite: Richter, C., Schneider, M., Wolf, D., Walther, F., Hausdorf, B., Hovakimyan, H., Sahakyan, L., Fuchs, M., and Faust, D.: Quantifying Quaternary climate variability in the Southern Caucasus using gastropod shell isotope transfer functions and climatic niche modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18140, 2026.
The area of the White Forest (Puszcza Biała), located in the north-eastern part of Mazovia, stretches between the Narew and Bug rivers and occupies a region in east-central Poland. Over the last four hundred years, its landscape has changed markedly from dense forest, through a period of growing human pressure, to present-day efforts at restoration and renaturation. In the Middle Ages and early modern period, the forest was protected by the bishops of Płock against excessive exploitation. This situation changed during the partitions of Poland: both the Prussian and later the Russian administrations intensified logging and gradually expanded settlement. In the 20th century, centrally planned economic policies further stressed local ecosystems, for example through extensive land drainage and melioration.
In this project, we present results from four short organic sediment cores collected in different parts of the White Forest, at Morzyczyn, Nowa Wieś, Wszebory and Zarzetka. We analysed the cores using X-ray fluorescence (XRF), pollen analysis (palynology), macroscopic charcoal, subfossil Chironomidae (non-biting midges) and basic sedimentological methods. By combining Chironomidae data with the other proxies, we investigate how different levels of human activity have affected nearby aquatic ecosystems. Although humans have always been closely connected with nature, this region offers an unusually good opportunity to separate human and natural influences. We can draw on rich historical records documenting population, land ownership and agriculture, and we know a great deal about the climate history of the last few centuries. Together, this allows us to disentangle the specific impact of human activity on local water bodies.
Our approach represents a unique integration of archival data (written historical sources) with environmental archives (paleoecological reconstructions derived from biogenic sediments from oxbow lakes and/or peatlands, as well as comprehensive soil analyses). In this way, gaps or uncertainties in one line of evidence can be cross-checked and complemented by the other. The studied sites also differ in parish affiliation and in how the surrounding land was managed, which helps us compare contrasting land-use histories. Riparian zones began to be intensively cultivated only after 1764, when river regulation and large-scale forest clearing were introduced, significantly altering the region’s hydrology. This system enabled part of the local population to survive the crisis of the 19th century, and it remained in use until 1947.
Notably, the studied timeframe encompasses two major crises: the first related to crop failures between 1840 and 1890, when natural conditions led to famine and disease; and the second—an ecological crisis around 1980, when an increase in deformities of the Chironomidae mentum (mouthpart) on head capsules appears in the record, which we attribute to intensified human impact and pollution.
This project is funded by the National Science Center (No. 2021/43/B/HS3/02636).
How to cite: Gruszczyńska, A., Związek, T., Sobechowicz, Ł., Witkowski, K., Łuców, D., Łotysz, S., Kaucha, K., Słowiński, M., and Obremska, M.: Four Centuries of Human Impact on Aquatic Environments in the sediments of the Bug River oxbow lakes (Mazovia, Poland), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1089, https://doi.org/10.5194/egusphere-egu26-1089, 2026.
Quantifying the magnitude and timing of hydroclimatic changes throughout Earth’s history is central to determining Earth’s hydrological sensitivity. Here, we present a novel method for quantifying hydroclimatic changes during the Late Quaternary using evidence from a global database of changes in lake sizes of closed-basin lakes. Closed-basin (or endorheic) lakes provide a powerful yet underutilized archive of past hydroclimatic conditions during periods of increased effective moisture.
We reconstructed hydroclimatic conditions over the past ~25,000 years across a global dataset of closed-basin lakes using the Budyko–Fu water-balance model, modern climate data, independent paleo-temperature reconstructions, and an advanced evaporation model corrected for changes in lake salinity. This quantitative reconstruction of both precipitation and evaporation enables us to reconstruct the magnitudes and spatial evolution of the dominant atmospheric circulation systems worldwide.
Our results reveal coherent regional hydroclimate patterns in both the extent and direction of circulation changes. In western North America, the moisture track was shifted ~600 km SW in the Early Holocene, and ~900 km NW in the Late Holocene, relative to the present climate. In western Central Asia, the westerlies-dominated region was shifted ~900 km NNE during the Deglacial period and ~1100 km NW during the Late Holocene. The East Asian monsoon expanded ~300 km W-NW during the Early and Late Holocene. The African monsoon expanded ~750 km NE in the Early Holocene. Using these results, we quantify the extent of global desertification that occurred since the last glacial period. This quantitative paleo-hydroclimatic reconstruction demonstrates the potential of closed-basin lakes to constrain past atmospheric circulation dynamics and provides a robust benchmark for ground-truthing global climate models.
How to cite: Brall, N., Steiger, N., and Goldsmith, Y.: Quantifying global aridity of the Late Quaternary from closed-basin lakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19358, 2026.
Understanding the impact of the ongoing Global Change on plant communities requires long-term quantitative reconstructions of past vegetation dynamics. The general lack of robust land cover data over centennial to millennial timescales has hindered answers in long-standing ecological debates, such as the natural versus anthropogenic drivers of open ecosystems. In this regard, palaeoecological tools like fossil pollen offer the possibility of exploring the past vegetation history, yet for their accurate interpretation differential pollen productivity must be taken into account.
In this contribution, we obtained the first relative pollen productivity estimates (RPPs) for continental Spain, by using all available modern pollen samples from the Eurasian Modern Pollen Database (EMPD2), and vegetation data from the Spanish Forestry Map (MFE) and the Iberian and Macaronesian Vegetation Information System (SIVIM). To test the accuracy of our RPPs, we validated arboreal taxa in present-day coretops across Spain and compared the RPPs with other studies in Europe.
Our results indicate that the dominant arboreal taxa (Pinus, evergreen and deciduous Quercus) are high pollen producers, whereas temperate forests, shrub and herbaceous taxa generally yielded medium to low estimates of pollen productivity. These findings would support the idea that the Iberian landscape would have been home to a heterogeneous mosaic of open areas, conifers and broadleaf trees, offering new frameworks to improve palaeoecological reconstructions. This contribution highlights the need to use publicly accessible databases and provides new outputs that can be used in future palaeoecological analyses.
How to cite: Jungkeit-Milla, K., Abraham, V., Sevilla-Callejo, M., Font, X., Romanos, H., García-Prieto, E., Aranbarri, J., Leunda, M., Farrell, M., Franco-Múgica, F., Mariani, M., Mazier, F., Sainz-Ollero, H., González-Sampériz, P., and Gil-Romera, G.: Novel relative pollen productivity estimates for Iberian taxa: implications for quantitative reconstruction of past vegetation dynamics in the Western Mediterranean , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11013, 2026.
Numerous quantitative calibration methods have been developed for preparation of quantitative paleoclimate reconstructions from microfossil proxies. Here we evaluate the performance of seven calibration approaches, using h-block cross-validations (Telford & Birks 2009) of calibration models fitted to (sub-)continental scale datasets of modern pollen assemblages and climate. We use a total of seven calibration methods falling into three methodological families: three classical unimodal methods including weighted averaging (WA), weighted averaging-partial least squares (WAPLS), and maximum likelihood regression curves (MLRC); three machine-learning methods based on regression-tree ensembles including random forest (RF), extremely randomized trees (ERT), and the boosted regression tree (BRT); and the modern-analogue technique (MAT) based on matching fossil assemblages with modern pollen samples.
Using ecologically grounded, regionally selected climate variables, we prepared h-block cross-validations in four regions: Northern Europe (July and January temperature), Southern Europe (January temperature), eastern North America (July temperature and annual water balance), and Africa (annual water balance). The cross-validations were run with a range of h values from 0 to 1500 km, to assess the performance of the models with a gradually diminishing pool of modern analogues (Salonen et al. 2019). The cross-validation performance was evaluated using the root-mean-square error of prediction (RMSEP), maximum bias, and the coefficient of determination (R2).
In our results (Fig. 1) we find the machine-learning methods (BRT, ERT, and RF) to be the three best-performing (lowest RMSEP) approaches at moderate h values in all cases except in Africa (Fig. 1F) where WA performs best, perhaps due to the robustness of the parametric modelling approach of WA with the more spatially clustered modern pollen data in Africa. A distinct pattern is observed with MLRC, with relatively high RMSEP values but often clearly the lowest maximum bias (Fig. 1C,E,F). In general, the between-method differences are considerably greater in maximum bias than in RMSEP. In all cases here, the maximum bias figures represent bias towards the modern gradient mean at either gradient end. Hence the maximum bias can be highly relevant in cases where paleo-reconstructions must be prepared from environments similar to the modern gradient end.
Our work highlights the practicality of the variable-radius h-block cross-validation approach. While the merits of h-block cross-validation are well argued, the method involves the challenge of selecting a suitable h, representing a balance between removing pseudoreplicate samples and an excessive loss of modern analogues (Trachsel & Telford 2016). By running cross-validations at a range of h, we find that after an initial loss of performance with increasing h, the performance tends to plateau at h of about 200–1000 km. This allows the identification of calibration methods that perform robustly at a range moderate h values.
Figure 1. Performance of calibration methods with different datasets. Methods are ranked based on increasing RMSEP in h-block cross-validations, using an h of 200 to 600 km depending on dataset.
References
Telford RJ & Birks HJB (2009) Quat. Sci. Rev. 28:1309–1316. https://doi.org/10.1016/j.quascirev.2008.12.020
Trachsel M & Telford RJ (2016) Clim. Past 12:1215–1223. https://doi.org/10.5194/cp-12-1215-2016
Salonen JS et al. (2019) Sci. Rep. 9:15805. https://doi.org/10.1038/s41598-019-52293-4
How to cite: Salonen, S., Kinyanjui, R., Camuera, J., and Tallavaara, M.: Assessment of European, North American and African pollen-climate calibration models in h-block cross-validations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14774, 2026.
Posters on site: Tue, 5 May, 14:00–15:45 | Hall X5
The thermal history of continental Eurasia and regional responses to anthropogenic warming remains poorly understood prior to instrumental records. Like the faster-than-global warming of the Arctic1, southern Siberia has also warmed rapidly, which leads to increasing recurrence of heat waves and drought, escalates wildfires2, and increases the vulnerability of regional permafrost against thaw3. Due mainly to the lack of long, well dated and quantitative climate records from vast Siberia, the anthropogenically-driven regional warming cannot easily be placed in a longer-term perspective. Clumped isotope analyses on biogenic carbonates can provide quantitative estimates (TΔ47) of the (water) temperature during the formation of these carbonates.
Here we use clumped isotope thermometry on lacustrine carbonates (bivalves, gastropods) from shallow (<2.5 m) Lake Ochaul, c. 100 km NW of Lake Baikal (N54°14′, E106°28′; 641 m a.s.l.). Clumped isotope analyses were conducted at Northumbria University on both modern and fossil shell material (N = 22) from a >7 m long, 14C-dated sediment core4. The oldest sample is from the Last Glacial Maximum (∼25 ka BP), while two modern samples were collected in 2023. Shells were manually cleaned and homogenised using an agate mortar and between four and 28 replicates (each weighing 120 to 350 mg) were analysed using a clumped-isotope-dedicated NU Perspective IRMS.
As Lake Ochaul is ice-covered between October and April, and the biogenic carbonate from the analysed molluscs forms preferentially in the warm summer season, the obtained TΔ47 values represent warm season water temperatures. The reconstructed temperatures range from +2.5±6°C to 21±4°C, with the highest values well in the range of modern water and air temperatures observed during July and August.
Our TΔ47 results indicate that until the mid 19th century, warm season water temperature of Lake Ochaul closely followed summer insolation. Warm season water temperatures were highest during the Holocene Thermal Maximum5 and declined in response to lower summer insolation during the later Holocene. Interestingly, all core top and modern samples show TΔ47 values significantly higher than expected if insolation was the sole forcing on temperature. This is consistent with lake water temperatures today, which reach values characteristic of the Holocene Thermal Maximum. Consequently, as modern water temperatures deviate so strikingly from the insolation trend, the results of this study indicate that anthropogenic warming now drives regional temperature dynamics in southern Siberia.
References
1 Hantemirov et al. (2022) Current Siberian heating is unprecedented during the past seven millennia. Nat. Comms. 13:4968
2 Huang et al. (2024) Escalating wildfires in Siberia driven by climate feedbacks under a warming Arctic in the 21st century. AGU Advances 5, e2023AV001151
3 Vaks et al. (2025) Arctic speleothems reveal nearly permafrost-free Northern Hemisphere in the late Miocene. Nat. Comms. 16:5483
4 Kobe et al. (2022) Not herbs and forbs alone: pollen‐based evidence for the presence of boreal trees and shrubs in Cis‐Baikal (Eastern Siberia) derived from the Last Glacial Maximum sediment of Lake Ochaul. JQS 37, 868–883
5 Tarasov et al. (2025) Environmental and cultural transformations in the Lake Baikal Region reflect hemispheric-scale changes in temperature and atmospheric circulation over the past 8800 years. GPC 256:105157
How to cite: Breitenbach, S. F. M., Umbo, S., Box, M., Gliwa, J., Modestou, S., Kobe, F., Shchetnikov, A. A., Bezrukova, E. A., Leipe, C., and Tarasov, P.: Summer temperatures in southern Siberia not seen since the Holocene Thermal Maximum, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4519, https://doi.org/10.5194/egusphere-egu26-4519, 2026.
Past intervals of warming provide the unique opportunity to observe how the East Asia monsoon precipitation response happened in a warming world. However, the available evaluations are primarily limited to the last glacial-to-interglacial warming, which has fundamental differences from the current interglacial warming, particularly in changes in ice volume. Comparative paleoclimate studies of earlier warm interglacial periods can provide more realistic analogs. Here, we present high-resolution quantitative reconstructions of temperature and precipitation from north-central China over the past 800 thousand years. We found that the average precipitation increase, estimated by the interglacial data, was only around one-half of that estimated for the glacial-to-interglacial data, which is attributed to the amplification of climate change by ice volume variations. Analysis of the interglacial data suggests an increase in monsoon precipitation of ~100 mm for a warming level of 2°C on the Chinese Loess Plateau. Chinese loess reveals a ~100-mm monsoon precipitation increase under 2°C of past interglacial warming.
How to cite: Gao, X.: Changes in monsoon precipitation in East Asia under a 2°C interglacial warming, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5173, https://doi.org/10.5194/egusphere-egu26-5173, 2026.
Speleothems represent important paleoenvironmental archives that can record environmental changes over thousands of years and can be dated reliably using the 230Th/U method. The relatively closed and chemically stable cave environment favours the preservation of organic compounds in addition to commonly used proxies such as stable isotopes and trace elements. [1,2]
Sterols are of particular interest as organic biomarkers because they are stable under low-oxygen conditions and originate from different sources, including plants, animals, and microbial processes. Cholesterol and sitosterol, derived mainly from animals and plants, respectively, can be transformed by microbial activity into stanols, which are often linked to faecal inputs. Coprostanol is especially relevant as an indicator of human activity, as it is a dominant stanol in human faeces. While sterol-based biomarkers are widely applied in soil and sediment studies, their use in speleothem research is still limited. This is mainly due to the complex carbonate matrix of speleothems and the generally low concentrations of organic compounds. A simple ultrasonic bath extraction was demonstrated to be an efficient and highly reproducible method for sterol recovery. Subsequent analysis was carried out using high-performance liquid chromatography coupled to atmospheric pressure chemical ionization high-resolution Orbitrap mass spectrometry (HPLC-APCI-HRMS), offering excellent sensitivity and mass resolution.
This analytical strategy significantly improves the extraction and detection of sterols in speleothems and provides a robust framework for extending their application in paleoenvironmental and anthropogenic reconstructions. As a proof of principle, sterol compositions were analysed in speleothems from diverse geographical regions, including Germany, Vietnam, France and Lebanon.
[1] A. Blyth et al. Quat. Sci. Rev. 149 (2016) 1-17. [2] J. Homann et al. Biogeosciences. 20 (2023) 3249–3260.
How to cite: Schäfer, J., Snowling, C., Nehme, C., Breitenbach, S., and Hoffmann, T.: Sterol Biomarkers as Indicators of Environmental Change and Anthropogenic Signals in Speleothem Records, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7934, 2026.
The accurate enumeration of microscopic particles is essential for deriving a wide range of climate proxies from sedimentary archives. Traditionally, particle counts require visual examination by microscopy, a time-consuming process that often analyses a small aliquot of the total sample material. As a result, rare particle populations and fine-scale variability are often poorly constrained, as a fast method to count an entire sample remains elusive. Here, we present a flow cytometric approach that enables the near-complete quantification of rare particle populations using high-throughput, multispectral imaging. We demonstrate this method using fossil pollen obtained from 0.5 cm3 peat core samples collected from the Falkland Islands. Analysis takes less than 2 hours per sample and images nearly all the particulate matter. These improvements in speed and precision facilitate the detection of smaller-scale fluctuations as well as the robust quantification of rare particle types. Using an isopycnic approach, we further show that this method can accurately track non-native, wind-blown pollen species that constitute <1% of the assemblage. Imaging flow cytometry can thus reveal changes that are impractical to find manually, expanding the range and resolution of climate proxies obtainable from sedimentary records.
How to cite: Forman, E., Thomas, Z., Power, A., Hughes, P., Peaple, M., Love, J., Scaife, R., and Reeves, E.: Rapid enumeration of rare microscopic particles in sedimentary archives using imaging flow cytometry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9806, 2026.
The Youngest Toba Tuff (YTT) super-eruption ~74 kyr BP (VEI 8.8) was the largest volcanic event of the Quaternary, estimated to have erupted 2800 km3 of magma. The ash cloud ejected by the YTT impacted insolation and atmospheric processes including the East Asian Summer Monsoon (EASM). The EASM is a major moisture source for continental Asia, including the Chinese Loess Plateau (CLP). The YTT eruption has also been associated with a shift into the cooler, drier climate of Greenland Stadial 20.
Highly resolved and well dated palaeoclimate records that could help elucidate the impact of the YTT eruption on the hydroclimate of the CLP are lacking. Using a 10,000-year-long strontium isotope record (obtained via LA-ICP-MS) from a stalagmite from the southeastern CLP we reconstruct regional aridity at very high resolution (~5 years).
Strontium isotope ratios reflect the mixing of two distinct strontium sources: loess, representing atmospheric dust input; and local limestone bedrock, the weathering of which is controlled by hydrological dynamics. These two sources can be linked to regional hydroclimate as contributions from loess increase when the region is dustier and generally drier, while wetter conditions would result in an increased contribution from the host rock above the cave. The speleothem strontium isotope record indicates a prominent shift from a more humid to more arid climate, which began to take effect ~1000 years before the YTT eruption. Thus, this local climatic shift could not have been triggered by the volcanic event but related to a longer-term weakening in the EASM (beginning ~75 kyr BP).
Our reconstruction shows that regional climate had shifted to increasingly arid conditions well before the YTT eruption. Our data further suggests that the impact of the YTT eruption on regional hydrological conditions was limited and that the EASM was not greatly impacted over a long time period.
How to cite: Burnham, A., Longman, J., Ersek, V., Breitenbach, S. F. M., Cutler, N., and Standish, C.: Strontium Isotopes Reveal Long-Term Drying of the Chinese Loess Plateau Well Before the Toba Super-Eruption, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11184, 2026.
This contribution is based on integrated investigations of inland dune sites in Poland, representative of dune systems in Central Europe and of aeolian landscapes in the central part of the European Sand Belt. The profiles comprise successions of aeolian sands intercalated with fossil soil horizons and organic-rich layers, recording alternating phases of dune activity and surface stabilisation from the Late Pleniglacial through the Late Glacial and into the Holocene.
The analytical framework combined bulk sediment geochemistry, grain-size analysis, spectrophotometric measurements, and absolute dating using optically stimulated luminescence (OSL) and radiocarbon (^14C) methods. This multi-proxy approach allowed assessment of depositional conditions, degrees of pedogenic transformation, and the temporal relations between phases of aeolian accumulation, stabilisation, and reactivation. Geochemical analyses focused on variations in major and trace element concentrations and on indices commonly applied in reconstructions of weathering intensity and element redistribution. Granulometric and spectrophotometric data supported the identification of sedimentary and soil-related signals within the analysed successions.
The results reveal consistent geochemical and sedimentological contrasts between aeolian sands and fossil soil horizons across all investigated sites. Fossil soils are characterised by relative enrichment in weathering-related elements and pedogenic indices, whereas aeolian sands display more homogeneous geochemical compositions indicative of limited post-depositional alteration and repeated aeolian reworking. Grain-size distributions are dominated by well-sorted sands, punctuated by episodic shifts towards coarser fractions that reflect short-lived high-energy depositional events. OSL and ^14C ages document multiple phases of aeolian activity and surface stabilisation spanning the Late Pleniglacial, Bølling–Allerød, Younger Dryas, and the Holocene.
These patterns are interpreted as expressions of the high sensitivity of inland dune systems to short-term climatic oscillations, which controlled vegetation cover, surface moisture, and sediment availability. Phases of climatic amelioration promoted dune stabilisation and soil formation, whereas cooler or more unstable conditions favoured renewed aeolian activity. While regionally coherent trends are observed across the study area, the magnitude and expression of geochemical and sedimentological signals vary between sites, highlighting the role of local environmental controls in shaping the palaeoenvironmental record. Overall, the study demonstrates the high sensitivity of inland dune–soil systems to climatic variability and underlines the value of integrated geochemical and chronological approaches for reconstructing the long-term evolution of aeolian landscapes in the European Sand Belt.
How to cite: Mroczek, P., Sokołowski, R. J., Zieliński, P., Moska, P., Skurzyński, J., Raczyk, J., Poręba, G., Piotrowska, N., Łopuch, M., Krawczyk, M., Jary, Z., Ustrzycka, A., Wojtalak, A., Szymak, A., Tudyka, K., and Adamiec, G.: Sensitivity of inland dune systems to Late Glacial and Holocene environmental change in Central Europe inferred from the geochemical record, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11374, 2026.
Quantitative climate and environmental reconstructions for continental surfaces require well-calibrated proxies inclusive of knowledge about how soil and sediment properties are actually linked to climatic and hydrological conditions via processes. While widespread terrestrial archives- like Loess–Palaeosol Sequences (LPS) covering more than 10 % of our planet preserve soils and sediments that formed under changing environmental conditions, the quantitative performance and transferability of commonly applied cost-efficient geophysical proxies remain incompletely constrained across climatic gradients. This strongly limits the valorization of these key-archives for terrestrial paleoclimates with implications for our knowledge about past and ongoing changes in our climate system and associated response processes.
Here, we evaluate the sensitivity and predictive accuracyof multiple soil property proxies—rock magnetic parameters, colorimetric indicators, and grain-size distributions—using modern topsoil samples from the Upper (Germany) and Middle (Serbia) Danube Basin. These regions provide well-defined gradients in temperature and moisture availability and serve as controlled framework for developing and testing transfer functions based on modern climate. Our results indicate that single-proxy models capture climate-related variability with moderate success, whereas multi-proxy regression substantially improves predictive performance, highlighting the nonlinearity and complementary nature of individual soil formation intensity indicators.
Building on this calibration effort, ongoing work extends the analysis along a transect covering the Danube catchment (Germany, Austria, Hungary, Serbia, and Romania). This dataset integrates modern soils with interglacial palaeosols, with a particular focus on units attributed to the last interglacial, (Marine Isotope Stage 5e). Rather than directly comparing fossil soils with modern meteorological parameters, we are trying to investigate whether climate- and moisture-sensitive relationships among soil properties persist through time and can be used to derive quantitative palaeoenvironmental information.
By combining modern calibration, multi-proxy transfer functions, and spatial integration, our study advances the quantitative use of geophysical soil proxies for reconstructing Quaternary palaeoenvironmental variability and clearly addresses both the potential and limitations of these approaches.
How to cite: Ryzner, K., Vinnepand, M., Bosnić, M., Stojakowits, P., Markovic, S., Gavrilov, M., Amiri, Z., and Zeeden, C.: Modern Soil–Palaeosol Proxy Relationships in European Loess: Implications for Quantitative Climate Transfer Functions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11964, 2026.
The White Forest is located in Eastern Poland, approximately 50 km north of Warsaw. The forest is bordered by the Narew and Bug rivers. In order to reconstruct changes in vegetation cover under anthropogenic pressure over time, sediments from the Stawinoga palaeolake and the Zarzetka oxbow lake were examined using pollen and radiocarbon analyses.
Palaeolake Stawinoga is situated approximately 2 km east of the present-day Narew River channel. The palaeolake is currently a circular, treeless wetland surrounded by pine forest. For the palaeoecological analysis, a 2-m-long sediment sequence was collected from the central part of the wetland.
The lower part of the Stawinoga core consists of gyttja, which is characterized by a high concentration of aquatic plant pollen grains (Myriophyllum, Potamogeton, Nymphaea), whereas the upper part is composed of peat. Pollen data indicate that Lake Stawinoga formed during the Late Glacial, as evidenced by high abundances of light-demanding taxa, including Juniperus, Hippophaë, Artemisia, and Chenopodiaceae. A detailed pollen analysis was performed on the upper peat deposits, which contain numerous plant indicators of human activity, including Cerealia pollen grains. Based on anthropogenic indicators appearing in the pollen spectra, different phases of human activity related to land use were identified.
The Zarzetka oxbow lake is located approximately 0.4 km south of the modern Bug River channel and is currently almost completely overgrown. The Zarzetka core was collected from a marginal, overgrown part of the lake. In total, 55 cm of gyttja deposits were sampled. The accumulation of gyttja in the Zarzetka core began approximately 40 (or 60) years ago, as indicated by the radiocarbon date of -1580±30 BP (1,983–1,985 cal AD). The Zarzetka core sediments are characterized by very high abundances of pollen indicators of human activity, on the basis of which phases of anthropogenic impact were distinguished. This facilitated the analysis of changes in human activity within this area.
The research was funded by the NCN OPUS-22 grant; Project ID: UMO/2021/43/B/HS3/02636 (Biskupie drzewa. Historia środowiskowa Puszczy Białej).
How to cite: Tsvirko, D., Obremska, M., and Związek, T.: Pollen record of human activity in the White Forest area (Mazovia, Poland), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18309, 2026.
The study of the environmental context in which the earliest human settlements developed is essential to understand the factors that shaped the dispersal and occupation of territories. To achieve this, the integration of comparable, quantitative palaeoecological proxy data across broad spatial and temporal scales is fundamental. The main objective of this study is to provide a palaeoecological reconstruction of Early Pleistocene sites with and without evidence of human presence, in order to assess ecological differences and evaluate the influence of environmental factors on early human occupation. Several climatic and ecological variables were reconstructed, including temperature, precipitation, seasonality, Net Primary Productivity (NPP), and Total Herbivore Biomass (THB), across sites from Europe, the Caucasus, and the Near East, ranging in age from 2.0 to 0.8 Ma, with Dmanisi (Georgia) representing the oldest and level TD6 of Gran Dolina (Sierra de Atapuerca, Burgos) the most recent. Climatic variables were obtained using the open-access R package pastclim, while NPP values were estimated using the NCEAS model based on mean annual temperature and annual precipitation; THB was subsequently derived from NPP values as an ecological proxy. The PCA results indicated that human presence was associated with ecosystems characterized by intermediate to low ranges of precipitation and productivity, including the lowest values observed, and with comparatively warmer conditions. On the other hand, humans were absent from ecosystems with the highest precipitation and productivity values. The reconstructions presented here constitute a first step toward characterizing the environmental conditions associated with early human settlements and will serve as a foundation for future studies focusing on herbivore mammal communities and the ecological settings of these archaic human groups.
How to cite: Trejo, B., Karampaglidis, T., and Rodríguez-Gómez, G.: Climatic and adaptive constraints for the first humans in western Eurasia., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19760, 2026.
Lake sediments preserve critical information about past environmental changes, yet traditional analytical approaches examine proxies in isolation at limited resolution. We present a framework for integrating multiple non-destructive, high-resolution imaging techniques to generate comprehensive, openly accessible datasets that capture the full complexity of sedimentary biogeochemical signals.
We combine three complementary imaging methods at resolutions of 40-200 μm: μXRF elemental mapping (inorganic composition), Hyperspectral Imaging (HSI, pigment analysis), and Mass Spectrometry Imaging (MSI, organic molecules). This generates datasets with up to 3,000 variables per pixel, enabling deductive exploration of sediment patterns rather than traditional single-proxy reconstructions.
A critical challenge is the lack of standardised protocols for acquiring, processing, and sharing high-resolution imaging data. Building on the open-source napari-sediment environment, we aim to create accessible tools for data harmonisation, enabling consistent integration and analysis of independent datasets.
Our approach emphasises FAIR data principles. We are establishing protocols for long-term storage and exploring integration with existing databases (e.g., PANGAEA, Neotoma). The goal is to create a publicly accessible biogeochemical fingerprint database that links sediment composition to specific environmental conditions—analogous to genetic databases.
Initial applications focus on Swiss lakes spanning various trophic states and altitudes, with records covering 16,000 years. Linking recent sediments (~200 years) to instrumental monitoring data will allow us to validate biogeochemical signals and establish reference fingerprints.
This framework follows the philosophy of PalaeOpen closely by: (1) making high-resolution multi-proxy downcore datasets publicly available, (2) providing standardised workflows enhancing data interoperability, and (3) enabling large-scale comparative analyses informing conservation strategies. The resulting database will facilitate accurate interpretations of past changes and improve our ability to anticipate ecosystem responses to climate change, ensuring sedimentary archives contribute maximally to understanding and protecting natural heritage.
How to cite: Zahajská, P. and Vogel, H.: Pixel2Paleo - High-resolution imaging of lake sediments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20502, 2026.
Posters virtual: Fri, 8 May, 14:00–18:00 | vPoster spot 4
EGU26-15510 | Posters virtual | VPS7
Analysis of quantitative pollen-based reconstructionsFri, 08 May, 16:15–18:00 (CEST) vPoster Discussions
Quantitative estimates of Holocene climate conditions have been developed since the 1960s using space‑for‑time calibration approaches. Although hundreds of reconstructions are now available globally, questions persist regarding their accuracy. We evaluate quantitative reconstructions derived from three sources: site‑specific studies, regional reconstruction compilations, and regional products generated from global databases. The focus is on Holocene pollen‑based reconstructions, which remain the most widely used indicators of terrestrial paleoclimate and on North American Arctic and treeline regions. Reconstructions developed at individual sites often display substantial high‑frequency variability, including anomalous values and abrupt shifts, reflecting in part calibration-related artifacts. Regional averages (“stacks”) reduce some of this variability, yet comparisons based on different reconstruction sources reveal divergences. Conversely, studies analyzing paired cores from a single lake or from closely spaced sites frequently demonstrate strong replication and relatively low reconstruction error. Multi‑proxy analyses of Arctic cores likewise reveal both areas of agreement and persistent discrepancies. Addressing these inconsistencies remains a challenge for Holocene climate reconstruction.
How to cite: Gajewski, K.: Analysis of quantitative pollen-based reconstructions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15510, 2026.
