This session aims to integrate recent developments in the field and invites submissions from a broad range of cave- and karst-related studies from orbital to sub-seasonal timescales.
In particular we welcome contributions from:
(1) (quantitative) reconstructions of past climatic and environmental variables to reconstruct precipitation, vegetation, fire frequency, temperature etc. across different climate zones,
(2) field- and lab-based developments of process-based methods to improve our application of proxy variables,
(3) process and proxy-system model studies as well as integrated research developing and using databases such as SISAL (Speleothem Isotope Synthesis and AnaLysis).
We further welcome advancements in related and/or interdisciplinary areas, which pave the way towards robust (quantitative) interpretations of proxy time series, improve the understanding of proxy-relevant processes, or enable regional-to-global and seasonal-to-orbital scale analyses of the relationships between proxies and environmental parameters. In addition, research contributing to current international co-ordinated activities, such as the PAGES working group on Speleothem Isotopes Synthesis and AnaLysis (SISAL) and others are welcome.
Orals: Mon, 4 May, 14:00–18:00 | Room F1
The use of δ234U as a paleoclimatic proxy in stalagmites has remained sporadic, despite uranium isotopes being routinely obtained through U-Th dating. Here, we investigate δ234U values in six stalagmites from Ejulve cave (northeastern Iberia) spanning the last 260 ka. Elevated δ234U values are attributed to selective leaching of 234U from damaged lattice sites and recoil-induced oxidation, with an additional accumulation of 234U recoils resulting from alpha-decay after growth hiatuses. This selective leaching mechanism weakens under conditions of enhanced bedrock dissolution, resulting in lower δ234U values.
The mechanisms controlling δ234U are primarily governed by infiltration frequency and the exposure of mineral surfaces to percolating solutions. However, the efficiency of these processes is strongly modulated by temperature, through its control on soil respiration, soil CO2 availability, and the intensity of bedrock dissolution. This interpretation is supported by the consistent long-term correlation between δ234U and sea surface temperatures from the Atlantic Iberian Margin, with lower δ234U values observed during warmer SST intervals. During stadials and glacial maxima, lower temperatures likely reduced vegetation cover and soil respiration rates, thereby decreasing soil CO2 concentrations and overall carbonate dissolution rates. Under such conditions, preferential leaching of 234U from bedrock surfaces is enhanced due to lower bulk rock dissolution. In addition, the high elevation of the study area and the occurrence of frequent winter frosts may have promoted repeated freeze–thaw cycles, inducing microfracturing and increasing the exposure of fresh mineral surfaces to selective leaching.
Conversely, warmer conditions during interstadials and interglacials promoted higher soil respiration rates and soil CO2, accelerating bedrock dissolution and yielding low δ234U values. This coupling between bedrock dissolution intensity and δ234U is clearly expressed by its correlation with stalagmite growth rate, with important implications. The link between δ234U, bedrock dissolution, and the initial dripwater oversaturation indicates that δ234U can serve as a valuable complement to δ13C, as both proxies are strongly influenced by soil respiration and soil CO2, and thus reflect soil and vegetation productivity sensitive to both humidity and temperature. A further implication is that, unlike δ13C, uranium isotopes are not fractionated during prior calcite precipitation (PCP). Consequently, δ234U can be combined with PCP-sensitive proxies such as Mg/Ca or δ44Ca to disentangle PCP variations driven by changes in drip rate from those related to shifts in the initial saturation state of dripwater. Finally, we advocate for the broader use of δ234U as a paleoclimatic proxy in speleothem-based studies from other cave systems.
How to cite: Pérez-Mejías, C., Wang, J., Ning, Y., Moreno, A., Delgado-Huertas, A., Edwards, R. L., Cheng, H., and Stoll, H. M.: Climatic controls on speleothem initial δ234U: evidence from Ejulve Cave over the last 260 ka, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3642, https://doi.org/10.5194/egusphere-egu26-3642, 2026.
Understanding long-term interactions between fire activity, vegetation dynamics, and climate variability is essential for contextualizing recent environmental change in the Mediterranean/Balkan region. Speleothems represent a promising yet still underutilized archive for paleofire reconstructions, offering robust chronologies and the integration of multiple environmental proxies within a single, continuous terrestrial record.
Here we present biomarker results from a 220 mm long speleothem from Golubarnica Cave (North Macedonia), spanning approximately the last 1800 years. The record is continuous and constrained by U-Th dating, and combines polycyclic aromatic hydrocarbons (PAHs) as indicators of fire activity with n-alkanes reflecting vegetation composition and terrigenous organic matter inputs. Individual sampled layers integrate on average ~30 years, with both integration windows and temporal spacing ranging from sub-annual to multi-centennial scales, allowing the identification of long-term trends and abrupt shifts in fire-related molecular assemblages. This speleothem forms part of the PROMETHEUS project, which investigates fire-climate-ecosystem interactions using speleothem-based multi-proxy approaches.
The PAH record reveals multi-centennial phases of fire activity broadly corresponding to major late-Holocene climatic intervals. Low and relatively stable PAH concentrations characterize the early part of the record (approximately 2nd-6th centuries CE), indicative of a background fire regime. Fire activity increases during the Medieval Climate Anomaly, peaks in the 12th-13th centuries CE, and declines abruptly toward the end of the 13th century, marking the onset of a prolonged phase of reduced fire activity broadly consistent with cooler
conditions during the Little Ice Age. Fire-related signals increase again from the late 16th century onward toward the present. While primarily interpreted in terms of hydroclimatic variability, potential contributions from medieval socio-environmental changes and land-use practices cannot be excluded.
Throughout the record, PAH variability closely mirrors speleothem δ¹⁸O, indicating a persistent hydroclimatic control on regional fire regimes. The main fire maximum is chemically distinct, dominated by an extreme increase in retene (up to two orders of magnitude above background levels) and accompanied by pronounced increases in higher-molecular-weight PAHs, suggesting a major shift in fuel type and/or fire intensity involving resin-rich woody biomass rather than a simple increase in fire frequency. Low-resolution n-alkane data show a synchronous response during this event, including a temporary increase in total n-alkanes, a minimum in average chain length, and a subsequent increase in carbon preference index, pointing to short-lived changes in vegetation-derived organic matter inputs and/or preservation.
Overall, this study highlights the potential of high-resolution speleothem hydrocarbon records to capture multi-decadal to centennial variability in fire regimes and associated environmental processes, identifying hydroclimate as a primary driver of fire activity in the central Balkans during the late Holocene.
How to cite: Ardenghi, N., Columbu, A., Zanchetta, G., Bini, M., DeSantis, N., Isola, I., Regattieri, E., Shen, C.-C., Hellstrom, J., Drysdale, R., Milevski, I., and Argiriadis, E.: Reconstructing Fire, Vegetation, and Climate Variability over the Last ~1800 Years from a High-Resolution Speleothem Record in the Central Balkans, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21458, https://doi.org/10.5194/egusphere-egu26-21458, 2026.
We present a multi-proxy record of a speleothem from Cueva Fantasma (Atapuerca, N Spain) spanning 12.7–5.7 ka that documents inland Iberian hydroclimate variability and a local expression of the 8.2 ka event. U–Th chronology indicates continuous deposition with accelerated accretion (higher drip rates) between ~8.5 and 7.7 ka. From base to top, three morphological stratigraphic parts were defined: (i) transparent columnar calcite with low detrital input; (ii) a laminated interval of black, organic-rich calcite laminae with high detrital input; and (iii) an upper part reflecting post 8.2 ka event stabilization characterized by moderate growth, marked absence of black laminae, and lower detrital imprint. Fluorescence and oil-immersion petrography highlight that black carbon occurs as films and clustered particulates that follow the growth-lamina geometry, with films preferentially recorded or preserved along micro-columns. SEM–EDX identifies combustion-derived particulates comprising soot-like carbon films and ash-rich detritus within the calcite crystals and/or detritus matrix. Trace-element profiles exhibit co-enrichment especially in Mn and Th across 8.5–7.7 ka, consistent with enhanced soil flushing and drip-system reorganization. High-resolution δ¹⁸O and δ¹³C data indicate wetter, vegetation-active conditions prior to ~8.5 ka, a hydrological pulse during ~8.5–7.7 ka expressed by increased variability and δ¹³C–δ¹⁸O co-variability, and moderation thereafter. Thus, the 8.2 ka interval is captured not by a hiatus but by a facies and geochemical shift under wetter, more seasonal/flashy recharge, characterized by black laminae containing soot-like films and ash-rich detritus, Mn–Th peaks, and slightly accelerated growth. The combustion-derived particulates, soot-like films and ash-rich micrite/detritus, occur as closely spaced clusters which supports multiple discrete in-cave fire episodes. This interpretation is distinct from external wildfire fallout and is based on the tight lamina-scale coupling, and coeval hydrological proxies. This record provides the first speleothem evidence from Atapuerca of the 8.2 ka climatic anomaly embedded within regional Holocene hydroclimate variability, alongside independent evidence for repeated in-cave combustion during that interval.
How to cite: Hasözbek, A., Martín-Chivelet, J., Isabel Ortega, A., Parés Casanova, J., Vallverdú Poch, J., Terradillo Bernal, M., Font, E., Ribeiro, J., Jiménez Barredo, F., Isintek, I., and Constantin, S.: A 12.7–5.7 ka multi-proxy stalagmite record from Cueva Fantasma (Atapuerca, N Spain): inland Iberian hydroclimate variability with combustion-derived laminae during the 8.2 ka interval., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10810, https://doi.org/10.5194/egusphere-egu26-10810, 2026.
During the Last Glacial Period, Earth was characterised by rapid millennial-scale climate oscillations, known as ‘Dansgaard–Oeschger’ (D-O) events, associated with large-scale reorganisations of oceanic and atmospheric circulation. While such variability is well documented in Northern Hemisphere high-latitude archives, such as Greenland ice cores, its expression remains less constrained in the Southern Hemisphere mid-latitude, raising the question of whether these climate disturbances, initiated in the North Atlantic Ocean, influenced rainfall patterns thousands of kilometres away in the Southern Hemisphere’s Southwest Pacific.
Here we present a new high-resolution speleothem composite record from Waipuna Cave (North Island, New Zealand), integrating two cores from the same flowstone aligned using a dynamic time warping approach. The composite spans 36.2–11.1 thousand years before present, and is constrained by 61 U–Th ages, yielding a mean age uncertainty of ~250 years (2σ). Combined stable isotope (δ18O, δ¹³C) and trace element (Mg/Ca) profiles provide a multiproxy record of hydroclimatic variability at Southern Hemisphere mid-latitudes.
The Waipuna record reveals rapid millennial-scale variability that resembles Dansgaard–Oeschger (DO) events. Periods of reduced regional water balance (precipitation minus evapotranspiration) on New Zealand’s northwest coast are consistent with large-scale atmospheric and oceanic reorganizations involving a shift of the rainfall belt, or the Intertropical Convergence Zone (ITCZ), and modulation of the Southern Westerly Winds. Comparison with well-dated, monsoon-sensitive speleothem records from equatorial to subtropical latitudes suggests that the Waipuna hydroclimate variability forms part of a broader pattern of global atmospheric reorganisation.
These results highlight the sensitivity of the Southwest Pacific mid-latitude hydroclimate to the large-scale atmospheric circulation changes during the last glacial period and emphasize the importance of the Southern Hemisphere records for constraining the understanding of the interhemispheric climate coupling. In the context of ongoing climate change, such past analogues may inform future shifts in subtropical rainfall distribution and extreme precipitation events.
Keywords: Last Glacial Period, Speleothem, New Zealand, Interhemispheric teleconnections.
How to cite: Dubois, M., Drysdale, R., Hellstrom, J., Lise-Pronovost, A., Fox, B., Hoepker, S., and Hartland, A.: North Atlantic drivers of Southern Hemisphere rainfall: A high-resolution speleothem record from Waipuna Cave, New Zealand., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10137, https://doi.org/10.5194/egusphere-egu26-10137, 2026.
The timing of drought occurrence on the Yucatán Peninsula has been a central focus of research linking Maya cultural evolution to regional hydroclimatic variability over the past several millennia. Climate proxy records that span periods of cultural decline and political instability are particularly valuable for constraining potential causal relationships. Numerous studies have proposed such links, most recently supported by sub-annual drought reconstructions (James et al. 2025, Science Advances). However, the precise and accurate determination of absolute ages for drought events and drought-related growth hiatuses remains a major challenge.
Advances in radiometric dating of speleothems, including 230Th/U and 14C methods, as well as independent stratigraphic approaches such as visual laminae counting and geochemical or isotopic proxy cycles, have substantially improved chronological resolution over the past decade. Nonetheless, combining independent dating techniques introduces important pitfalls related to systematic uncertainties. Corrections for initial 230Th can substantially degrade age accuracy, as they rely on the assumption of a single, well-characterized source rarely constrained by multiple measurements (e.g., isochrons). These corrections introduce systematic uncertainties that may exceed those associated with individual layer counts by up to two orders of magnitude. Conversely, layer counting alone provides absolute age control only when robust anchor points are available or when records are demonstrably continuous, and it requires independent constraints to interpret proxy-derived periodicities.
Here, we compile and assess available speleothem 230Th/U data from the Yucatán Peninsula to (i) evaluate the impact of variable initial 230Th on chronological precision and accuracy, (ii) identify pitfalls associated with combining radiometric dating and annual layer counting, and (iii) demonstrate quasi-continuous speleothem growth across the region over the past 3000 years. Our analysis reveals substantial geochemical variability in initial 230Th concentrations in drip waters from different cave systems, indicating a strong potential for underestimated systematic uncertainties, particularly at the onset of discontinuous chronologies. While annual layer counting based on geochemical proxies independent of water isotopic composition or vegetation changes can significantly reduce relative age uncertainties, systematic errors persist and require careful evaluation. Using more than 20 speleothem chronologies, we further document the frequency and regional coherence of growth hiatuses and their changes across the Terminal Classic Period. Integrating chronological data with soil-sensitive tracers allows assessment of critical thresholds in soil CO₂ concentration, drip-water availability, cave–drip water CO₂ gradients, and carbonate oversaturation.
Overall, our results highlight that accurately constraining drought timing from speleothem records remains challenging, underscoring the need for rigorous methodological integration and transparent quantification of systematic uncertainties.
How to cite: Frank, N., Warken, S., Schorndorf, N., Mielke, A., Lases Hernandez, F., and Avìles Olguìn, J.: Quasi - Continuous growth of speleothems on the Yucatan Peninsula and possible drought modulated hiatuses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17289, https://doi.org/10.5194/egusphere-egu26-17289, 2026.
Interannual rainfall variability in the Kalahari Desert is strongly controlled by the El Niño-Southern Oscillation (ENSO). Paleo-reconstructions of hydroclimate (wet-dry) cycles in this area may therefore provide insights into the past behaviour of ENSO. Here, we present new petrographic and geochemical data of Late Holocene speleothem samples from Gcwihaba Cave, Botswana. The cave system, which is home (colony) to large numbers of bats, formed in highly karstified metamorphic dolomite. The studied speleothems consist of calcite and aragonite laminae at micrometer to millimetre-scales. High-resolution mineralogical, stable carbon (δ13C) and oxygen (δ18O) isotope ratios, and trace elemental concentrations, combined with chronological constraints (14C and U-Th data) and layer counting under the optical microscope, suggest that calcite/aragonite duplets record annual to interannual fluctuations in hydroclimate. Wet conditions favor calcite formation, whereas aragonite forms preferentially during the dry period. Speleothem lamina thickness is closely linked to the annual infiltration, which is controlled by seasonal aquifer recharge cycles. High-resolution laser-ablation trace-element (TE) analysis and isotope data support the petrographic observations. Calcite carbonate farming experiments in the cave revealed that aragonite and calcite are in distinct layers and well-preserved. There is no evidence in modern precipitates of dissolution-reprecipitation processes that lead to the transformation of aragonite to calcite. Of all TE, Y and La appear to be the best rainfall proxies, reflecting their transport pathway from the soil horizon at the top of the cave to the speleothem via drip water. Synchronous occurrences of higher Y and La with calcite phases suggest wet conditions, i.e., more rainfall. In contrast, aragonite layers exhibit higher concentrations of Sr, Ba, and U, and increased fluorescence due to the presence of organic matter, which possibly originates from bat guano deposits. However, this proposition requires further investigation. Aragonite formation can be linked to drier conditions in the cave, which are accompanied by an increase in the drip water Mg/Ca ratio. Drier conditions also increase the likelihood of preserving air-borne dust (guano particle) deposition rich in phosphorus from the cave interior within speleothem layers. Our results highlight that mixed calcite-aragonite speleothems provide a robust archive of high-frequency (annual to interannual) hydroclimate variability in southern Africa.
How to cite: Samanta, A., Sinha, N., Wassenburg, J. A., Borsato, A., Frisia, S., Franchi, F., Lechleitner, F., Oh, Y., Yang, Y. S., Cheng, H., Bruxelles, L., Moore, A. E., and Timmermann, A.: A speleothem mineralogy perspective on interannual wet-dry cycles in Botswana during the Late Holocene, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8808, https://doi.org/10.5194/egusphere-egu26-8808, 2026.
Speleothem fluid inclusion isotope analysis provides the oxygen and hydrogen isotope composition of the parent water from which the carbonate precipitated (d18OFL; d2HFL). In contrast to carbonate isotopes, it is not affected by kinetic isotope effects. Fluid inclusion isotopes can be analyzed by crushing heated speleothem fragments and measuring the isotopic composition of the released water vapor. However, during this process, analytical artifacts related to pre-crushing evaporation and/or post-crushing adsorption can occur, potentially skewing the isotope values away from their origin and biasing temperatures calculated from the combination of d18OFL and d18OCc. In d2H-d18O cross-plots, analytical (pre-crushing) evaporation has been suggested to induce very shallow slopes down to 1.4, lower than trends induced by evaporation under natural conditions in the soil or inside the cave.
In this study, we used a Picarro L2140i isotope analyzer with an artificially generated moist background setup to examine the effect of analytical evaporation by quantifying the water loss prior to analysis when applying different crushing temperatures. We targeted two layers with different calcite fabrics from a flowstone of Touhami Cave (GTOF2), Morocco, as well as speleothems from Scladina Cave, Belgium and Bloukrantz Cave, South Africa.
The samples have different water contents and show different isotope effects of analytical evaporation that highly depend on the crushing temperature. Our results indicate that high water content samples (>1-2 µL/g) are generally more reliable compared to low yield samples (<0.5 µL/g), although high yield samples can be altered significantly by in crusher evaporation. In contrast to crushing at 110°C or 125°C, crushing at 90°C prevents most analytical evaporation in the samples we analyzed, increasing the sample water yield by up to 50%. Furthermore, for our low water content samples different crushing temperatures of 110°C and 125°C result in different evaporation slopes. At 110°C, the evaporation slope can even be parallel to the global meteoric water line. A potential explanation for these different evaporation slopes involves various amounts of adsorption of water to freshly crushed calcite powder, although this requires further exploration.
These findings have crucial implications, especially for low yield samples, because data that plot in the vicinity of the global meteoric water line are generally regarded as trustworthy. In our experiments, crushing at 90°C produces accurate d18OFL, d2HFL, and d-excess values for all high yield samples. Realistic cave air temperatures from combined d18OCc and d18OFL analysis is retrieved from all samples analyzed, supported by consistent TEX86 temperatures and modern-day drip water isotope compositions.
How to cite: Wassenburg, J., Schröder, J., Skeidsvoll, A., Basu, S., Maccali, J., Meckler, A. N., Fernandez, A., Budsky, A., Cleary, D. M., Martinez-Garcia, A., Yang, Y. S., Oh, Y., Cheng, H., Spötl, C., and Vonhof, H. B.: Improved accuracy of oxygen and hydrogen isotope analysis in speleothem fluid inclusions: the importance of crusher temperature, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16783, https://doi.org/10.5194/egusphere-egu26-16783, 2026.
Stalagmites record valuable information within their crystal structure and composition about past climate and environmental changes. Stalagmite crystal fabrics reflect growth conditions: the crystallisation pathway influences the distribution of nano- to micro-particulates, crystal defects, and nano- to micro-porosities. These microstructures may act as nucleation sites for the formation of larger fluid inclusions — small cavities encapsulating relic drip water that are important climate archives. Stalagmite fluid inclusions are widely used for paleotemperature reconstructions using nucleation-assisted microthermometry and oxygen isotope thermometry. However, the influence of different crystallisation mechanisms and fabrics on fluid inclusion properties (e.g., water density and composition) and their preservation is still poorly constrained.
Here, we apply a crystallographic approach to investigate the internal crystal structure of two calcite stalagmites from Borneo and New Zealand. Our aim is to assess whether fluid inclusions are affected by post-growth deformation and/or volume changes and to quantify their impact on microthermometric data. This work seeks to identify non-thermal processes that could explain the observed scatter in microthermometry measurements from coeval fluid inclusions.
Previous electron backscatter diffraction (EBSD) analyses showed these samples exhibit columnar compact, open, and porous fabrics composed of mm- to cm-scale crystal domains, further subdivided into sub-domains characterised by rotations around the c-axis of up to 4°. Fluid inclusions are preferentially located along these sub-domain boundaries, indicating a strong relationship between fluid inclusion nucleation and crystal defects. High-angular resolution EBSD (HR-EBSD) reveals residual stresses up to 200–300 MPa located along the sub-domain boundaries. Since stalagmites form in a nominally stress-free environment, these stresses are interpreted as remnants of crystallisation energy stored in the lattice as crystallographic defects. High-resolution transmission electron microscopy (HR-TEM) confirms the presence of high densities of edge dislocations located along the sub-domain boundaries, that bend the crystal lattice and generate the observed misorientations and stress fields.
Our results demonstrate that fluid inclusions are located in mechanically fragile microstructural environments. The internal stresses stored by these microstructures may be released in response to external forces such as sample preparation or ambient temperature changes and could induce post-formation volume changes in fluid inclusions, ultimately biasing paleotemperature reconstructions. These quantified stress values provide a basis for evaluating the magnitude of this effect on microthermometric data.
How to cite: Pasqualetto, L., Krüger, Y., Menegon, L., Demurtas, M., Frisia, S., Borsato, A., Pósfai, M., Pekker, P., van Schrojenstein Lantman, H., and Meckler, N.: Residual stresses preserved in calcite from cave stalagmites and its impact on fluid inclusions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14611, https://doi.org/10.5194/egusphere-egu26-14611, 2026.
Recent studies have demonstrated the efficacy of high-precision ∆′17O analysis in carbonates, biogenic and abiotic origin, to deduce geological and environmental processes. The δ17O values can be influenced by processes such as kinetic fractionation during carbonate precipitation, which is associated with the hydroxylation of CO2, thereby making it an emerging proxy crucial for interpreting the oxygen isotopic ratio in carbonates and improving the accuracy of palaeoclimate reconstruction efforts (Bajnai et al., 2024). Δ′17O in cave carbonates helps determine the various factors influencing speleothem formation, including evaporation, condensation, and cave kinetics, which have been inadequately captured by the conventional dual-isotope (δ18O and δ16O) systematics. We follow the framework developed by (Huth et al., 2022) wherein interpretations of speleothem formation are done by examining trends of data spread through the distribution of triple oxygen isotopes in Δ′17O versus δ′18O space, with the conventional excess of 17O expressed as Δ′17O = δ′17O – λRL * δ′18O. By comparing triple oxygen isotopic compositions across various speleothem samples from different caves in North East India, this study seeks to improve our understanding of the control mechanisms on Δ17O variability and its utility in reconstructing past environmental conditions. The analysis of samples involved the acid digestion (in ~105 % H3PO4) of carbonate powders (~10 mg) followed by the catalytic CO2-O2 exchange reaction method as followed in the triple oxygen isotope analysis (Fosu et al., 2020) using in-house equipment with a quartz reactor containing Pt sponge (99.98% trace metal purity). The results yielded Δʹ17O in the range of -83 to -129 per meg. When plotted in the Δ′17O versus δ′18O space, the data expands across three dominant controlling factors, majorly indicating an interplay of cave kinetics, Rayleigh distillation and cave temperature. This study proves that Δ′17O in cave carbonates act as a potential proxy for identifying fractionation processes.
References
- Bajnai, D., et al. (2024). Correcting for vital effects in coral carbonate using triple oxygen isotopes. Geochemical Perspectives Letters, 31, 38–43.
- Huth, T. E., at al. (2022). A framework for triple oxygen isotopes in speleothem paleoclimatology. Geochimica et Cosmochimica Acta, 319, 191–219.
- Fosu, B. R., et al. (2020). Technical Note: Developments and Applications in Triple Oxygen Isotope Analysis of Carbonates. ACS Earth and Space Chemistry, 4(5), 702–710.
How to cite: Subba, R. and Ghosh, P.: Identifying Cave Carbonate Isotope Fractionation Mechanisms through Triple Oxygen Isotope Analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1039, https://doi.org/10.5194/egusphere-egu26-1039, 2026.
Karst landscapes of Peninsular Malaysia preserve some of the most important terrestrial archives of Quaternary fauna and paleoenvironmental indicators. Due to its location in between the Indochina and Sundaic subregions, the peninsula is critical for assessing faunal dispersal, landscape contiguity, and climatic fluctuations effects on the ecosystem. Published fossil and geochronological evidence from cave sites across the peninsula are synthesised to evaluate the faunal habitat structure and ecological variation from the Middle Pleistocene to the Last Glacial Maximum (LGM).
Early Quaternary research in the peninsula was largely conducted through geological, sedimentological, and palynological records, often in placer tin-mining pits. It was suggested that vegetation cover during the LGM and earlier glacial phases was reduced and more open relative to the present day. Pollen preserved within alluvium deposits indicates cooler, drier climates, with grassland–savanna and pine woodland corridors. These interpretations were embedded within broader landscape evolution models including deep weathering of exposed basement in Mio-Pliocene time during the maximum extent of the Sundaland continent, regolith mobilisation after the initiation of slumping due to the rise of sea levels and precipitation, braided fluvial aggradation, episodic interglacial downcutting, the development of peneplanation and pedogenesis followed by the establishment of modern fluvial, infill of V-shaped valleys in association with high-sea level deposits along the coast during the Late Pleistocene.
Numerically dated karst cave fossil assemblages provide a new insight to complement these open-site models. The persistence of orangutan (Pongo sp.) at Batu Caves until ~60 ka implies continued lowland forest cover along the west coast during the last glacial phase. Pleistocene small mammal assemblages from Semadong Cave, located in the northern peninsula, feature environmental variability with the co-occurrence of grassland- and forest-affiliated taxa suggesting a mosaic vegetation model under cooler and drier conditions. Reflected by the occurrence of arboreal mammals including Pongo and colobine monkeys, the Middle–Late Pleistocene Layang Mawas Cave represents an assemblage that is dominated by species closely tied to tropical forest habitats.
Notable recent finding includes the first reported occurrence of Stegodon in Peninsular Malaysia, which was discovered together with a Pongo within the same Middle Pleistocene stratigraphic unit. Based on the ecological tolerances of modern Pongo and stable isotope evidence from fossil Pongo and Stegodon elsewhere in Southeast Asia and adjacent regions, it is reasonable to infer that the palaeoenvironment at this site was either under continuous forest cover or comprised a mixed landscape, with forest patches interspersed within more open vegetation. Recent studies on palaeoecological records across Southeast Asia and pollens from South China Sea during the LGM further challenge the “savanna corridor” paradigm and support the concepts of “forest” and “mosaic vegetation” across Sundaland.
Collectively, karst cave archives in Peninsular Malaysia add critical faunal constraints to existing sedimentary and palynological frameworks. Future combination of stable carbon and oxygen isotope data on fossil remains, with high-resolution rainfall and monsoon proxies will further refine paleoenvironmental reconstructions in the peninsula, subsequently contribute to a better understanding of the paleoenvironment in this region.
How to cite: Muhammad, R. F.: Karst Records of Quaternary Fauna and Environments in Peninsular Malaysia: A Literature Review, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18068, https://doi.org/10.5194/egusphere-egu26-18068, 2026.
The karst of the Yorkshire Dales, situated in the Pennine hills of northern England, provides an under realised opportunity for paleo climate studies in mid latitudes. It was marginal to the Last Glacial Maximum British and Irish Ice Sheet.
The valley is surrounded by extensive moorland underlain by sandstone and mudstone dominated Millstone Grit Group strata. Underlying the Millstone Grit are strata of the cyclothemic Yoredale Group which include cavernous limestone units. The incision of the Upper Nidderdale valley has partially removed the clastic cover revealing limestone beds within the Yordale succession in three valley floor inliers.
By far the most extensive cave system is that beneath the main valley where the River Nidd in normal conditions sinks into the Limley inlier through impenetrable fissures upstream of Manchester Hole. The underground river from Manchester Hole flows into Goyden Pot, then onto New Goyden Pot to finally resurges at Nidd heads Risings forming a combined system with over 9 km of passages. The main stream passage and main chamber of Goyden Pot are floored by fallen blocks indicating collapse has played a major part in cave development. Some of the blocks consist entirely of speleothem and many show evidence of re-dissolution including incision and the development of scalloped surfaces cutting across the original depositional structure.
U-series dating of speleothem from the Goyden Pot cave system has shown that the incision of the upper reaches of the Nidd valley must have exposed the limestone strata of the Limley, Thrope and Lofthouse inliers prior to the Last Glacial Maximum and cave development was well underway by early MIS 3. The nature of the samples so far dated show the presence of significant detrital thorium seriously limiting the precision of the work.
The Canal Cave system is located in the Lofthouse inlier and consists of a narrow east-west orientated passage containing a 5 m climb with the upstream (western) end blocked by calcite. Down cutting of the River Nidd has intersected the route of the passage, thus draining the cave, which can be traced across the riverbed as a slot leading to the downstream continuation under the east bank. The sample was again contaminated by detrital thorium resulting in a considerable loss of precision as has been found elsewhere in the valley however a late Pleistocene date is indicated for the basal part of the sample (14136 +11.7 - 11.3 ka BP). This shows the cave was drained and thus valley of the River Nidd at Lofthouse had incised close to its present level by the very latest late Pleistocene.
How to cite: Murphy, P.: Incision, Instability and isolation- attempting to constrain cave development in the most easterly of the Yorkshire Dales, northern England, UK, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2599, https://doi.org/10.5194/egusphere-egu26-2599, 2026.
The Bruniquel Cave contains circular structures made of broken stalagmites, dated to 176.5 ka and attributed to Neanderthals (Jaubert et al., 2016). A key question concerns the origin of the speleothem pieces used in these structures (i.e., speleofacts) and whether Neanderthals intentionally broke stalagmites, or instead collected fragments already lying on the cave floor—an important distinction in terms of intentionality. A related issue is the provenance of these speleothems within the cave, implying a particular selection process indicating potential symbolic value of speleothems for Neanderthals.
Two broken stalagmite bases and one broken stalagmite near the structures in the Salle de la Structure were investigated. U-series dating of the outer layers of the broken bases and stalagmite, as well as of the initial calcite layers that subsequently covered them, yielded ages from 432.8 ± 29.8 ka to 121.3 ± 1.2 ka. The broken base BR-201, produced similar ages for the older and younger calcite, allowing a precise age of 176.5 ± 2.1 ka for the breakage of this ~20 cm diameter stalagmite—consistent with the age of the structures. This result strongly supports breakage by the same Neanderthals who built the structures, and suggests an opportunistic selection of building material.
Laser-Induced Breakdown Spectroscopy (LIBS) with an in-house portable device was performed on speleothems from different sectors of the cave, and on speleothem pieces incorporated into the structures. Multivariate statistical analysis (e.g., principal component analysis), reveal compositional differences, mainly in Mg content, between speleothems from the entrance zone and those from the deeper parts of the cave. To date, the geochemical signature of the speleothem pieces used in the structures matches that of speleothems from the interior of the cave, failing to attribute the building material to a specific place in the cave, which would be an argument for a specific symbolic value.
Other calcite deposits in the Salle de la Structure were dated to constrain the cave floor conditions during Neanderthal occupations. These ages range from 163.0 ± 39.3 ka to 2.8 ± 4.1 ka. The results indicate that calcite deposition occurred in some areas during or shortly after the construction of the structures, implying that the floor surface in these zones likely remained relatively stable thereafter. In contrast, other areas were covered by calcite only during the Holocene. These findings help identify surfaces where human traces may be preserved and contribute to reconstructing the cave’s morphology during Neanderthal times by spotting the more recent calcite deposits that should be removed from the 3D model of the cave.
The study is financed partly by the French Ministry of Culture (DRAC), the Belgian Science Policy Office (BELSPO) and the Research Foundation Flanders (K208822N)
Jaubert J., Verheyden S., Genty D., et al., 2016. Early Neandertal constructions deep in Bruniquel Cave in southwestern France. 2016. Nature 534: 111 114.
How to cite: Verheyden, S., Jaubert, J., Burlet, C., Bengattat, S., Génuite, K., Delaby, S., Cheng, H., and Jia, X.: Speleothems used by Neanderthals, in the Bruniquel Cave, Southern France., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12788, https://doi.org/10.5194/egusphere-egu26-12788, 2026.
The transition from the Last Glacial period to the Holocene (T-I) represents the major global climatic reorganisation of occurred in the recent Earth’ history. T-I shows a complex reorganization of ocean-atmospheric climatic system and is pervasively characterised by abrupt climatic changes driven by the instability of Northern Hemisphere ice sheets and the impact on the Atlantic Meridional Overturning Circulation. The iconic climatic phases recognised in Northern Europe and Greenland ice core records are generally recognised also in the Mediterranean region, but structure, timing and eventual regional differences are poorly understood. Here we present a high-resolution multi-proxy speleothem record (stalagmite V3) from Abisso del Vento (Madonie Mountains, Northern Sicily) that spans over the T-I interval (from ca. 20 ka to 10.5 ka BP), comprising stable isotope (δ18O, δ13C) and trace element (Mg/Ca, Sr/Ca) records. Despite V3 proxy data shows the general climatic pattern recognised in Greenland ice cores some differences are observed, especially during the Greenland Interstadial 1 (GI1). Comparisons with various continental and marine records highlight the complexity of the Mediterranean region during T-I, and V3 offers a robustly dated multiproxy records to clarify this complexity.
How to cite: Zanchetta, G., Isola, I., Columbu, A., Drysdale, R., Madonia, G., Pollard, T., Hellstrom, J., Natali, S., Luppichini, M., Regattieri, E., and Vattano, M.: The structure and timing of Termination I in the Central Mediterranean from a multiproxy speleothem record from Sicily (Southern Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11275, https://doi.org/10.5194/egusphere-egu26-11275, 2026.
Two stalagmites, DH_Br2 and DH_Kn6, were sampled from excavations in Dechencave, western Germany. Both were precisely dated by the 230Th/U-method (Mainz University), thin sections were investigated (Mainz University), and both stalagmites were analysed for their stable oxygen and carbon isotope composition (Mainz University and Max Planck Institute for Chemistry, Mainz) as well as various trace element concentrations (Max Planck Institute for Chemistry, Mainz).
Both stalagmites show evidence for diagenesis, such as roundish voids and mosaic calcite fabric in their lower parts. These parts were excluded from further analyses due to the alteration of the 230Th/U-ages as well as the proxy data. The discussed section of stalagmite DH_Br2 started growing at 401 ka and stopped at 379 ka, which corresponds to late Marine Isotope Stage (MIS) 11c to mid-11a. Stalagmite DH_Kn6 grew between 394 and 390 ka and overlaps with that of DH_Br2. Overall, speleothem records from MIS 11 are rare, in particular from Central Europe.
The δ13C and δ18O records show different levels for both stalagmites, most probably related to different amounts of prior calcite precipitation (PCP) and disequilibrium isotope fractionation during calcite precipitation at the different drip sites. The trace element records of both stalagmites can be identified as different environmental proxies with Al and Y being proxies for detrital material in the stalagmites and P and U reflecting soil microbial and vegetation activity. Strontium and Ba were influenced by leaching of soil minerals as well as changes in stalagmite growth rates. The Mg records correlate well with the δ13C records indicating PCP as dominant controlling factor. All trace element records, except for Al and Y, and the δ13C values are proxies for past precipitation. As revealed by the proxy records of stalagmite DH_Br2, drier conditions prevailed between 401-395 ka as well as between 391-379 ka, whereas wetter conditions existed between 395-391 ka, which is probably related to insolation changes. According to the δ18O values of stalagmite DH_Br2, temperature was slightly lower during 389-379 ka, i.e., after the peak warm phase of MIS 11, in agreement with marine and Antarctic ice core records. During this period 389-379 ka, we observe millennial-scale oscillations, which are most prominent in the δ18O record of stalagmite DH_Br2. They are probably Dansgaard/Oeschger-like events, not described up to now from speleothems from Central Europe during MIS 11. These millennial-scale oscillations are in good agreement with sea surface temperature changes in the North Atlantic.
How to cite: Riechelmann, D. F. C., Vonhof, H., Schöne, B. R., Jochum, K. P., and Scholz, D.: Dansgaard/Oeschger-like events detected in MIS 11 speleothem proxy records from Central Europe, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13781, https://doi.org/10.5194/egusphere-egu26-13781, 2026.
Millennial-scale climate variability is a prominent feature of the last glacial cycle, intensively studied in Greenland ice cores as well as other marine and terrestrial climate archives. The most widely recognised expressions of abrupt millennial- to centennial- scale climate oscillations during this period are Dansgaard – Oeschger (D/O) events. For the past 125 ka, Greenland ice cores provide a benchmark for studying D/O events, but their restriction to the last glacial cycle limits investigations of the timing, duration and amplitude of D/O-type events during previous glacial cycles. Synthetic Greenland ice core data suggest that D/O-type millennial-scale climate variability occurred across all glacial phases of the past 800 ka. However, a major limitation for understanding the timing and dynamics of millennial-scale climate variability in preceding glacial cycles is the progressively more challenging dating of older material and the general lack of absolutely and precisely dated high resolution climate records beyond the last interglacial.
Here we present a new speleothem record from Cueva Victoria in SE Spain covering Marine Isotope Stages (MIS) 11a and 10, showing millennial-scale climate variability in both temperature and precipitation. Previous studies confirm that speleothems from Cueva Victoria are sensitive archives of past atmospheric and hydrological changes on both millennial and orbital timescales. For the last glacial cycle, numerous D/O events have been identified in Cueva Victoria speleothem stable isotope records, demonstrating their strong connection to North Atlantic climate patterns.
During MIS 11a and 10, millennial-scale variability is evident in multiple high-resolution proxies in the Cueva Victoria speleothems, such as stable carbon and oxygen isotopes, Mg concentrations, as well as TEX86-derived cave temperatures. The structure and timing of those millennial-scale events align closely with millennial-scale variability in marine sediment records, especially from the Iberian Margin, enabling direct comparison of temperature and precipitation dynamics in the marine and terrestrial realm. All events are characterised by a rapid increase in temperature and moisture availability, followed by a more gradual cooling and drying trend. This results in distinct stadial-interstadial D/O-type oscillations, particularly pronounced during MIS 10. The timing of these oscillations matches with the predicted occurrence of D/O events based on the synthetic Greenland ice core record, highlighting the potential of Cueva Victoria speleothems to reconstruct millennial scale climate variability beyond the last glacial cycle.
How to cite: Weber, M., Vonhof, H., Martínez-García, A., and Scholz, D.: Millennial-scale temperature and precipitation dynamics during Marine Isotope Stage 11a and 10, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11764, https://doi.org/10.5194/egusphere-egu26-11764, 2026.
Antarctic ice cores and ocean-sediment records preserve evidence for an increase in the amplitude of glacial-interglacial cycles at around 430 ka, known as the Mid-Brunhes Transition (MBT). However, similar evidence from non-polar terrestrial environments is rare, casting some doubt on the global extent of this transition. Here we present a multi-proxy speleothem record from Corchia Cave (Alpi Apuane, Italy) that spans the MBT. It comprises a stacked d18O and d13C time series from multiple stalagmites anchored in time by U-Th and U-Pb ages; and trace element, 87Sr/86Sr, and d18O and d13C profiles from a subaqueous calcite deposit (CD3) that has grown continuously from 970 ka to the present. We anchored the CD3 record to the chronology of a stalagmite stack by synchronisation of their respective d18O and d13C profiles.
CD3 is well suited to this study because it yields a suite of proxies from just a single specimen that covers multiple glacial-interglacial cycles either side of the MBT. In particular, its d13C profile provides a reference for comparing the amplitude of glacial-interglacial temperature changes at Corchia to globally integrated ice-volume (LR04 benthic 18O/16O stack) and greenhouse gas (ice-core CO2 and CH4)time series. The CD3 temperature record builds on a previous trace element study, which revealed that the Mg/Ca in this speleothem is strongly influenced by mineralisation temperature (a proxy for external air temperature at the cave site). This is supported by subsequent clumped-isotope palaeothermometry. We thus developed a continuous palaeotemperature time series for CD3 extending to ~650 ka via a Mg-D47 transfer function.
The temperature profile reveals compelling evidence for a shift in glacial-interglacial amplitude across the MBT. Temperatures during the interglacials of MIS15e, 15a and 13a are lower in Corchia compared to those of MIS11c, 9e, 5e and the Holocene; temperatures during MIS7e and 7c are the exception, only reaching the levels of the pre-MBT interglacials. Minimum glacial temperatures for MIS16 and 14 are warmer in Corchia than those of the subsequent glacial maxima, and the MIS12 and 6 glacials are the coldest of the last 650 kyr. All of these patterns are consistent with existing global ice-volume and greenhouse gas records but provide a rare and important terrestrial perspective. This finding confirms previous assessments that the MBT was global in extent.
How to cite: Drysdale, R., Pollard, T., Zanchetta, G., Regattieri, E., Isola, I., Hellstrom, J., Woodhead, J., Li, X., Couchoud, I., Edwards, L., Leger, J., Vezinet, A., Däeron, M., Meckler, N., Cheng, H., Spötl, C., and Fallick, A.: A speleothem record of the Mid-Brunhes Transition from southern Europe, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19357, https://doi.org/10.5194/egusphere-egu26-19357, 2026.
Understanding past climate trends is crucial for projecting future hydroclimate changes, especially in the context of rapid anthropogenic climate change. Here, we focus on reconstructing hydroclimate variability during periods of past climate change from the tropics , which remain underrepresented in climate variability studies despite their heightened vulnerability to ongoing climatic shifts.
Here, we investigate ẟ18O, ẟ13C, and trace elements (Mg/Ca, Ba/Ca, Sr/Ca) in multiple speleothem samples across the Philippines. Speleothem sample, BH-1, was collected from Hinagdanan Cave (9.6253° N, 123.8009° E) and grew between 26-51 kyrs B.P. with an average growth rate of 8.12 μm/yr. Another speleothem sample PPUR-GP-3 collected from the Puerto Princesa Subterranean River National Park (10.1926° N, 118.9266° E) grew between 4-48 kyrs B.P. with a hiatus between 16,243 ± 146 years B.P. to 35,300 ± 538 years (±2𝜎). Collectively, speleothem growth encompasses critical periods of past climate change such as Heinrich Events 1 through 5, the Younger Dryas, and the last deglaciation. Modern climatology data and ongoing cave monitoring data suggests that Hinagdanan Cave and Princesa Subterranean River National Park recharges from summer precipitation.
Initial geochemical findings indicate fluctuating trace element data suggesting drying trends over time, characterized by an increase in Mg/Ca and a decrease in Sr/Ca in PPUR-GP3. Change-point analysis conducted on the ẟ18O record in BH-1 reveals that Heinrich Event 3 in the Philippines experienced drying conditions. The drying is in alignment with ẟ18O trends reflected in Borneo stacked speleothem records. Further investigation of BH-1 and PPUR-GP3 trace elements and stable isotopes will disentangle regional (ẟ18O amount effect, moisture source) versus local (prior calcite precipitation) hydroclimate variability. Finally, we will compare our new geochemical results with existing isotope-enabled climate model simulations (iTRACE) to discern potential climate drivers that modulate IPWP hydroclimate during key climate events.
How to cite: Sekhon, N., Senan, S., Hart, M., Kong-Johnson, C., Yambing, J. O., Du, X., Vega, M. G., Belanger, B., Geronia, M., Jaladoni, S., David, C. P., Oster, J., McGee, D., and Ibarra, D.: Reconstructing Tropical Hydroclimate Variability using Speleothems from the Philippines During Abrupt Climate Events, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14602, https://doi.org/10.5194/egusphere-egu26-14602, 2026.
The natural variability of rainfall in the Southern African region remains, as yet, poorly understood due to scarce availability of long instrumental and pre-instrumental records and the sparse distribution of weather stations in remote areas. It is known that regional atmospheric circulation features, particularly the Botswana High, control the moisture distribution across the region on seasonal and interannual timescales. The El Niño-Southern Oscillation (ENSO) further influences moisture transport, resulting in alternating wet and dry periods. Understanding the interplay between these forcing in modulating natural rainfall variability is crucial for effective water resource management, agricultural planning, and climate adaptation in a region heavily reliant on seasonal rainfall.
Speleothems (secondary mineral cave deposits) are known to record local hydrology and rainfall over thousands of years and can provide valuable knowledge about natural rainfall variability in Southern Africa. Here, we present two speleothems from Gcwihaba Cave, located in northwestern Botswana, that span the late Holocene period between 200 and 2500 years before present (yrs BP). Robust age models for speleothems were constructed using a combination of U-Th and 14C dating techniques, despite signs of biocorrosion from bat guano in the cave. The two well-laminated speleothems exhibit alternating bands of calcite and aragonite, likely identifying annual to multi-annual timescales. High-resolution stable-isotope (δ18O and δ13C) and trace-element data from these speleothems reveal pronounced interannual variability, suggesting large fluctuations in rainfall amounts in the area, which can be linked to ENSO, as suggested by water tagging experiments with an isotope-enabled climate model. Analyzing multidecadal changes in interannual isotope and trace-element variability provides further insights into low-frequency ENSO dynamics during the late Holocene, which can then be compared with other paleo-ENSO reconstructions.
How to cite: Sinha, N., Samanta, A., Wassenburg, J. A., Borsato, A., Frisia, S., Franchi, F., Lechleitner, F., Oh, Y., Yang, Y.-S., Cheng, H., Bruxelles, L., Moore, A. E., and Timmermann, A.: Speleothem reconstructions of Holocene interannual climate variability in Botswana, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16045, https://doi.org/10.5194/egusphere-egu26-16045, 2026.
Abstract
Precisely dated East Asian summer monsoon (EASM) speleothem δ¹⁸O records frequently mirror Greenland ice-core variability during deglaciation and stadial–interstadial transitions, however, pronounced regional heterogeneity is evident, particularly during the penultimate deglaciation (Termination II; TII). Not all records align, and mismatches are often ascribed to chronological uncertainty despite high dating precision, yet they persist even in annually band-counted, confocal-imaged speleothem δ¹⁸O records, implying complexity beyond dating artifacts. This ambiguity sustains debate over whether EASM cave δ¹⁸O primarily encodes Asian monsoon intensity via moisture-source shifts or reflects upstream rainout, progressive isotopic distillation and is potentially modulated by precipitation seasonality.
In contrast, speleothem δ¹⁸O records from the Indian subcontinent provide a complementary perspective, with δ¹⁸O variability more directly reflecting Indian Summer Monsoon (ISM) circulation strength. To better constrain first-order Asian monsoon variability, we present a high-temporal-resolution, precisely dated speleothem δ¹⁸O record from Mawmluh Cave in northeastern India (hereafter ML11 δ¹⁸O). The ML11 δ¹⁸O record spans Termination II (TII) and is derived from a ~70-cm-long stalagmite, with a mean temporal resolution of ~5 years and average ²³⁰Th age uncertainties of ±600 years. Our ML11δ¹⁸O record resolves the evolution of the Indian Summer Monsoon (ISM) across TII, enabling robust assessment of monsoon structure and variability under changing boundary conditions. We examine what constitutes a “penultimate deglaciation” in a monsoon-dominated system, considering not only its precise timing but also its sensitivity to external forcing. Leveraging the high chronological precision of ML11 δ¹⁸O record, we evaluate similarities and potential differences between the ISM and EASM speleothem δ¹⁸O variability. Our new ISM δ¹⁸O record further tests whether the EASM speleothem δ¹⁸O reflects pan-Asian monsoon dynamics or is dominated by regional-to-local hydroclimate processes. These results highlight the need to integrate chronologically robust archives with regionally diagnostic proxy interpretations to better resolve monsoon behavior and improve constraints on monsoon sensitivity under future climate change.
How to cite: Kathayat, G., Thirumalai, K., Liangcheng, T., Dong, X., Spötl, C., Li, H., Saravanan, P., Zhang, H., and Cheng, H.: The anatomy of the Indian summer monsoon variability during the penultimate deglaciation (Termination II), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16599, https://doi.org/10.5194/egusphere-egu26-16599, 2026.
Speleothems are an important archive for reconstructing past climate variability. The Magnesium isotope proxy tested so far in limestone-hosted caves provides the possibility of reconstructing climate conditions from changes in the silicate-to-carbonate weathering ratio. Other caves, however, are situated in dolostone host rock. Consequently, the Mg content of the host rock is much higher than that of limestone. Dripwater monitoring in a set of dolostone-dominated caves in Germany and Morocco, as well as the collection of soil (silicate minerals), host rock (carbonate), and speleothem samples, aims to apply the Mg isotope proxy in dolostone-hosted caves. The time-series analyses of the Mg isotope composition of dripwaters revealed, for most dripwater sites, significant variations in δ26Mg values, which can be related to changes in the silicate-to-carbonate weathering ratio. Silicate weathering is enhanced under dry, warm conditions, whereas cold, wet conditions favour carbonate weathering. Due to significant differences in the Mg isotope composition of silicate (soil) and carbonate (host rock) minerals, changes in the weathering regime are detectable in drip-water Mg isotope ratios in both climate regions. In German caves, where changes in temperature are more pronounced than changes in rainfall amount, the weathering ratio is driven by temperature variations. In Morocco, however, both temperature and rainfall amount complement each other and drive changes in the silicate-to-carbonate weathering ratio. Furthermore, the different transfer times at each drip site ranged from a few months to at least a year. Some drip water sites show no variation in Mg isotope composition. In these cases, the signal of the weathering ratio is strongly buffered by longer water transfer times/residence times and mixing of waters in the aquifer. Although possible, no dependence of Mg isotope variations in the dripwaters on prior calcite precipitation was observed. Corresponding speleothems from the monitored dripwater sites exhibit varying Mg isotope compositions of calcite and aragonite. There is no overprint of other factors during carbonate precipitation; thus, these variations are solely due to changes in the silicate-to-carbonate weathering ratio and, consequently, changes in temperature and rainfall amount. Furthermore, observations on the Mg isotope fractionation factor of aragonite-dominated samples revealed a smaller Δ26Mg than for calcite speleothem samples. Generally, the Mg isotope proxy is a valuable tool for reconstructing past climate conditions in both limestone- and dolostone-dominated caves.
How to cite: Riechelmann, S., Schröder-Ritzrau, A., Wassenburg, J. A., and Immenhauser, A.: Magnesium isotope time-series analyses of dolostone cave dripwater and speleothems: Proxy calibration and application, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5348, https://doi.org/10.5194/egusphere-egu26-5348, 2026.
Stable carbon and oxygen isotopes in calcite are widely used to reconstruct environmental and hydrological conditions, but kinetic isotope effects related to CO₂ degassing and carbonate precipitation are still poorly quantified [1]
In particular, the role of water–air exchange geometry and water height on the δ¹³C (and δ¹⁸O) of precipitated calcite remains difficult to isolate from that of other controls in natural systems [2].
Here we present a series of laboratory precipitation experiments to establish an empirical relationship between air–water exchange geometry surface and ¹³C fractionation between calcite and Dissolved Inorganic Carbon, providing a framework to quantify how changes in exchange surface area and water height modulate δ¹³C signatures.
CaCO₃ precipitates from the same Ca2+–HCO₃- rich bottled water in containers with two exchange geometries: low vs high air–water exchange, expressed as S/h (air–water surface area divided by water height), with the low-exchange configuration having S = 130 cm² and h = 11.5 cm and the high-exchange configuration having S = 273 cm² and h = 5.5 cm. All experiments start from identical temperature, volume and initial chemistry. Conductivity, pH and temperature are measured every 24 h. Major ions concentrations, δ¹³C of DIC and δ¹³C of precipitated calcite are measured each day. Precipitation rates are quantified from the temporal decrease in dissolved Ca²⁺ concentration. They are higher when air–water exchanges increase: 1.0 × 10⁻³ mol L⁻¹ d⁻¹ for low air–water exchanges vs 1.6 × 10⁻³ mol L⁻¹ d⁻¹ for high air–water exchanges during the first day of the experiment. δ¹³C of calcite is higher for high air-water exchanges than for low air-water exchanges at a same time step (e.g., at second day: −7.1 ±0.2‰ vs −9.2 ±0.3‰).
δ¹³C of DIC increases by +8.5‰ (mean) for high air–water exchanges compared to +5.7‰ (mean) for low air–water exchanges over 4 days. However, the evolution δ¹³C of DIC with DIC concentrations appears to depend little on the air–water exchanges and follows an apparent Rayleigh-type trend.
The calcite–DIC enrichment factor ε becomes more negative with increasing precipitation rate, indicating stronger kinetic fractionation under conditions favouring rapid CO₂ degassing, consistent with the rate dependent trends observed in cave analogue precipitation experiment [3]. At low precipitation rates 4.3 × 10⁻⁴ mol L⁻¹ d⁻¹ , ε is close to equilibrium near to 0.2‰ compared to the equilibrium value of 0.5–0.8‰ at 17–23°C [4], whereas at higher precipitation rates 1.87 × 10⁻³ mol L⁻¹ d⁻¹, ε shows a much larger deviation from equilibrium, reaching −2.8‰.
These experiments provide quantitative data on isotope effects linked to exchange geometry and precipitation kinetics, that could be used to interpretations of δ¹³C signatures in natural carbonate deposits such as speleothems and tufas.
[1] Dreybrodt, W. & Fohlmeister, J. (2022) doi:10.1016/j.chemgeo.2021.120676
[2] Fairchild et al. (2006) doi:10.1016/j.earscirev.2005.08.003
[3] Hansen et al. (2019) doi:10.1016/j.chemgeo.2018.12.012
[4] Salomons, W. & Mook, W. G. (1986) doi:10.1016/B978-0-444-42225-5.50011-5
How to cite: Pietri-Orsini, S., Gillon, M., Emblanch, C., and Barbecot, F.: Kinetic carbon isotope effects during calcite precipitation: role of water–air exchange geometry and precipitation rate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4830, https://doi.org/10.5194/egusphere-egu26-4830, 2026.
Speleothems (stalagmites, stalactites, flowstones, …) are currently one of the best datable terrestrial archives valuably recording past environmental and climatic variability. Their geochemical composition reflects complex interactions between host rock, rainwater infiltration and soil processes dependent on climate (Fairchild & Baker, 2012). In particular, Mg, Sr and Ba are commonly linked to prior calcite precipitation related to water availability and therefore indirectly to rainwater amount (Fairchild et al., 2000), while other elements such as P or S, may reflect organic matter cycling or anthropogenic and marine aerosol inputs (Borsato et al., 2007). Despite their importance, high-resolution spatial profiling of trace elements in speleothems remain analytically demanding, often requiring destructive sample preparation and time-consuming laboratory workflows.
Within the framework of the LEAP project (Learning from the Past - https://www.leap-belgium.be/) funded by BELSPO, we developed and implemented a Laser-Induced Breakdown Spectroscopy (LIBS) hyperspectral imaging methodology to obtain rapid, minimally destructive trace-element profiles along speleothem growth axes. The approach combines automated raster scanning with synchronized multi-spectrometer acquisition, producing two-dimensional LIBS spectral images over scan widths of 15–20 mm at 100 µm spatial resolution. Elemental ratio maps (Mg/Ca, Sr/Ca, Ba/Ca) are generated from the hyperspectral data cube and converted into one-dimensional profiles by buffered averaging along growth-parallel transects. A robust filtering and masking strategy based on Ca signal thresholds and calculated plasma parameters allows efficient exclusion of spectra affected by surface defects, detrital inclusions or existing sampling holes.
The method was first validated through comparison with LA-ICP-MS elemental mapping on a reference speleothem section, showing consistent relative variations and stratigraphic coherence in Mg/Ca, Sr/Ca and Ba/Ca profiles. Following validation, multiple trace-element profiles were extracted from speleothems from Hotton, Père Noël and Remouchamps caves (Belgium). In the Père Noël cave for example, the approach enabled the extraction of a continuous >1 m long profile at 0.1 mm spatial resolution, demonstrating the capability of LIBS hyperspectral imaging to generate high-resolution geochemical records over large stratigraphic distances.
Applied to a flood-impacted speleothem (calcite floor) from the Hotton Cave, the LIBS-derived profiles also revealed distinct elemental profiles associated with thin detrital layers incorporated within the calcite. This allows a more precise and objective assessment of past extreme flooding events at that location that can be compared to population migration information and changes in funerary practices. This contributes to the investigation of the link between climatic and environmental changes and human behaviour in the LEAP project.
References:
Borsato, A., Frisia, S., Fairchild, I.J.,, Somogyi, A.,, and Susini,J. 2007. Trace Element Distribution in Annual Stalagmite Laminae Mapped by Micrometer-Resolution X-Ray Fluorescence: Implications for Incorporation of Environmentally Significant Species. Geochimica et Cosmochimica Acta 71 (6): 1494–1512.
Fairchild, I. J., & Baker, A. (2012). Speleothem science: From process to past environments. Wiley-Blackwell.
Fairchild, I. J., Borsato, A., Tooth, A. F., Frisia, S., Hawkesworth, C. J., Huang, Y., McDermott, F., & Spiro, B. (2000). Controls on trace element (Sr–Mg) compositions of carbonate cave waters: Implications for speleothem climatic records. Chemical Geology, 166(3–4), 255–269.
How to cite: Burlet, C., Verheyden, S., Deforce, K., Pincé, P., Bengattat, S., Boudin, M., Capuzzo, G., Crombé, P., De Groote, I., Delaby, S., De Mulder, G., Gillikin, D., Leonard, H., Olson, E., Snoeck, C., Vandendriessche, H., Van Maldegem, E., and Wojcieszak, M.: A LIBS hyperspectral imaging methodology for high-resolution element profiling of speleothems: applications within the LEAP project, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3993, https://doi.org/10.5194/egusphere-egu26-3993, 2026.
Speleothems are recognized as reliable archives of past continental climate dynamics. Depending on the research focus, both geochemical and petrographic proxies are employed. While previous studies have explored the petrographic features of speleothems - particularly mineralogy and crystal fabric development - the relationship between drip water geochemistry and the petrographic attributes of speleothems remains underexplored. Research indicates that several physicochemical parameters, such as drip rate, pH, supersaturation, growth rate, fluid Mg/Ca ratio, and organic matter content, influence the mineralogy and crystal morphology of cave carbonates. Among these, the Mg/Ca ratio of drip water is the most influential, directly affecting crystal morphology and serving as a proxy for prior calcite precipitation (PCP). Cave environments are subject to various factors that can alter drip water Mg/Ca ratios. To disentangle these effects, a series of cave analogue experiments were conducted in a climate chamber set to 15 °C and 70 % humidity under atmospheric CO2 conditions. Each solution was purified of organic material and maintained at a constant pH of 7.9 with a steady drip rate of 98 µL/min. Roughened watch glasses provided a crystallization surface for the carbonate precipitates. The fluid Mg/Ca ratio was the only variable, adjusted between experiments (0.5, 0.375, 0.25, 0.125). Each Mg/Ca ratio was tested both with and without the influence of PCP, with experiments lasting 90 days. Throughout this period, temperature, humidity, CO2 level, drip rate, conductivity, pH, and outflow element concentrations were continuously monitored. Carbonate precipitates were analyzed using SEM, EBSD, and EMPA. Initial results suggest that calcite crystal morphology varies with changes in fluid Mg/Ca ratio, and aragonite precipitates only form in experiments influenced by PCP at the same initial Mg/Ca ratio as non-PCP experiments.
How to cite: Hambsch, P., Riechelmann, S., Herwartz, D., and Immenhauser, A.: Influence of fluid Mg/Ca ratios on speleothem petrography – Insights from cave analogue experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4828, https://doi.org/10.5194/egusphere-egu26-4828, 2026.
Speleothems are among the most important terrestrial climate archives, combining precise chronologies with sensitivity to temperature and hydrology, yet reconstructing absolute temperatures remains challenging. While fluid inclusion microthermometry provides the most direct temperature constraints, it requires large, well-preserved inclusions and is not applicable to all samples. Emerging approaches such as TEX86 may require site specific calibrations and remain in early stages of development. Consequently, stable isotope-based approaches including fluid-calcite δ18O thermometry and clumped isotope Δ47 thermometry represent promising options for speleothem paleothermometry, despite both being affected by isotopic disequilibrium inherent to speleothem growth. Here, we evaluate whether empirical calibrations that incorporate mean disequilibrium effects can yield meaningful temperature estimates in a tropical setting. Using actively growing speleothems from caves in Borneo, we assess whether δ18O and Δ47 based thermometers can be applied despite expected disequilibrium, whether disequilibrium effects are consistent among samples, and whether particular speleothem morphologies are better suited for clumped isotope thermometry.
We measured calcite δ18O and Δ47, together with fluid inclusion δ18O, in stalagmites, stalactites, flowstones, soda straws, and pool carbonates. We find that oxygen isotope derived temperatures calculated using a speleothem specific calibration such as Tremaine et al. (2011) agree well with modern cave temperatures, with a 1σ spread of approximately 1.5 °C across 22 growth layers from nine different stalagmites. In contrast, Δ47 based temperatures show large sample dependent disequilibrium effects, with an approximately 4 °C 1 σ catter across 14 specimens. Only pool carbonates record Δ47 values consistent with isotopic equilibrium. These results indicate that for Holocene samples fluid-calcite δ18O thermometry can provide meaningful absolute temperatures with an inherent uncertainty of ± 1.5°C, whereas Δ₄₇ disequilibrium effects are highly variable and indicate that an empirical calibration incorporating mean disequilibrium would not yield robust temperature estimates. Pool carbonates emerge as the only speleothem type consistently suitable for clumped isotope thermometry
How to cite: Fernandez Bremer, A., Maccali, J., Krüger, Y., and Meckler, A. N.: Evaluating the limits and potential of fluid-calcite δ¹⁸O and Δ₄₇ thermometry in modern speleothems from Borneo, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18529, https://doi.org/10.5194/egusphere-egu26-18529, 2026.
Recovering liquid water from past precipitation on continental areas from mid- to low-latitude and analysing its water isotopes presents significant challenges. Paleoclimate archives such as groundwater, ice or speleothems provide direct access to paleowaters. Most of the paleoclimate reconstructions linked to past precipitation water isotopes are not directly based on analysis of paleo liquid water. They are measured, for instance, on carbonate, sediment or cellulose, all of which primarily derive from precipitation water, yet remain influenced by various fractionation processes during their formation.
Speleothems are advantageous as they can be found in all karstic regions of the Earth, at every latitude and on every continent. They contain fluid inclusions that encapsulated fossil drip water, corresponding to a mixture of precipitation water that fell above the cave area approximately at the time the inclusions were formed. It therefore constitutes thus a unique window into the past hydroclimate cycle for mid- to low latitude. Having better access to paleowater at lower latitudes than those of polar regions allows us to gather global information and understand the behaviour of past meteoric water.
Using published and novel speleothem fluid inclusion data from ~140 caves, we investigate the global behaviour of water isotopes in the past. We explore the spatial distribution of paleoprecipitation, construct a global meteoric water line and develop paleo-isotopic lapse rates for the Holocene and Pleistocene. Furthermore, we compare the speleothem data with observational stable isotope data and two model simulations, i.e. the AWI-ESM-wiso and the ECHAM6-wiso simulations.
How to cite: Affolter, S., Kipfer, T., Hofmeister, E., Werner, M., and Fleitmann, D.: Spatial behaviour of water isotopes in past global precipitation recorded in speleothem fluid inclusions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21838, https://doi.org/10.5194/egusphere-egu26-21838, 2026.
Börtlüce Cave (Manisa) in western Türkiye has a unique geographical location, which is a transition zone between tropical and polar atmospheric circulation systems, increasing its climate sensibility, and is a tectonically active region generating significant earthquakes, and lastly close to Kula Volcanic Field with remarkably well-exposed young volcanic structures. The cave is surrounded by significant archeological settlements, such as the ancient city of Sardis in Salihli, the capital of the Lydian Kingdom in the Bronze Age, where fossil footprints in volcanic ashes dated back to 4700 years ago (Ulusoy et al., 2019). Potential speleothem records from this cave therefore provide a valuable opportunity to explore paleoenvironmental changes in detail and to better understand how human populations responded to such changes.
Employing state-of-the-art methods, including U-Th dating, stable isotope (δ18O and δ13C), and trace element analyses, enables high-resolution and reliable reconstructions of hydroclimate variability, environmental evolution, and the effects of volcanic activity and earthquake-induced processes on cave environments.
Here we present initial records from two Börtlüce Cave stalagmites, reflecting changes in the stalagmite growth such as abrupt surface steps, growth axis deviations, and growth interruption. First results indicate that the occurrence of pronounced hiatuses in the underlying layers in stalagmites, accompanied by changes in fabric/stratigraphy and growth orientation, are consistent with seismic disturbance recurrences affecting drip hydrology rather than climatic forcing over the mid-late Holocene.
In addition to earthquake-induced changes, the isotope records from both stalagmites display similar isotopic patterns throughout the mid-late Holocene, indicating negligible kinetic fractionation effects in the cave. The δ18O values range between −7.4 and −4.2‰, while δ13C values vary from −9.3 to −3.7‰ along the growth axes of the stalagmites. Between 6 and 4 ka, both δ18O and δ13C values are depleted, reflecting wetter climatic conditions and enhanced soil biological activity. After ~4 ka and until ~2 ka, isotope values become progressively more enriched in both stalagmites, indicating a transition to drier climatic conditions accompanied by reduced soil activity. Two distinct dry intervals are recorded, corresponding to the 4.2 ka Bond event and a second event at approximately 3.2 ka. These intervals likely represent significant hydroclimatic deteriorations that may have impacted regional human communities. Understanding their responses will provide valuable information for assessing current and future climatic hazards such as droughts.
Ongoing analyses of both stalagmites, together with expanded sampling of additional stalagmites from Börtlüce Cave, aim to produce a comprehensive reconstruction of paleoenvironmental changes related to climate dynamics, volcanic influences, and seismic activity, and to evaluate their combined impacts on the archaeological record.
References
Ulusoy İ., Sarıkaya M.A., Schmitt A. K., Şen E., Danisik M., Gümüş E., 2019. Volcanic eruption eye-witnessed and recorded by prehistoric humans. Quaternary Science Reviews, 212, 187-198.
Acknowledgement
This research was granted by the National Science and Technology Council, Taiwan, ROC (111-2116-M-002-022-MY3;114-2116-M-002-016-MY3), Academia Sinica (AS-TP-113-L04), and National Taiwan University Core Consortiums Project (113L891902). The authors are grateful to Kamil Altıparmak, Ali Karataş, Tuğberk Yetiş, Yiğit Karakuzu, Faruk Bilmez, and Kula Municipality for their assistance during the fieldwork. The authors thank Mehmet Oruç Baykara for his support.
How to cite: Kolbüken, M., Unal Imer, E., Shen, C.-C., Huang, C.-Y., and Hu, H.-M.: Börtlüce Cave: A Natural Archive Linking Earthquakes, Volcanism, Climate Variability, and Human History in Western Türkiye, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4574, https://doi.org/10.5194/egusphere-egu26-4574, 2026.
Monitoring studies of cave systems are essential for understanding the hydrological and microclimatic processes that control the isotopic signatures preserved in speleothems and for improving the interpretation of paleoclimate records. Despite increasing efforts in recent years, many aspects of karst system responses to climate variability and change remain poorly constrained.
In 2023, a comprehensive cave and climate monitoring network was established across the Swabian Alb (N 48°30'60''; E 9°24'15''), a karstic region in southwestern Germany, covering both the Neckar and Danube catchments. Four caves were chosen for a monitoring infrastructure based on their location and accessibility: Bärenhöhle, Nebelhöhle, Schertelshöhle, and Hohle Fels. Continuous measurements of relative humidity, temperature and water dripping rates were conducted inside the caves. Measurements of cave air CO2 concentrations and dripping water samples were taken during periodic site visits. Dripping and spring water samples were analyzed for triple oxygen (δ18O and δ17O) and hydrogen (δD). External climate monitoring included temperature and precipitation measurements, as well as the isotopic analysis of rainfall and the calculation of δ17O-excess and δD-excess from rainwater collected at multiple locations on and around the Swabian Alb.
Preliminary results from the first year of monitoring indicate: (1) seasonal fluctuations in the concentration of CO2 in cave air due to winter ventilation and cave-air stagnation in summer, indicative of buoyancy-driven airflow between the surface and the cave; (2) a uniform air moisture source feeding the rainfall over the Swabian Alb; (3) caves and springs appear to be decoupled from short-term weather signals, implying integration over longer-term climatic conditions; and (4) the isotopic composition of rainwater seems to be related to the rainfall amount and temperature at the monitoring sites. By combining multiple-site and cave monitoring at different elevations and two basins of the Swabian Alb, this study provides new insights into the environmental factors controlling the isotopic signal and airflow dynamics in caves. These findings are essential for improving the interpretation of speleothem-based climate proxies and the sensitivity of karst systems to ongoing future climate change.
How to cite: Lo Triglia, D., Novello, V., Maisch, M., Ballian, A., and Rehfeld, K.: Implementing a cave and climate monitoring system across the Swabian Alb, southwestern Germany, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7468, https://doi.org/10.5194/egusphere-egu26-7468, 2026.
Medium to high elevations in the European Alps may experience enhanced warming in the future (Kotlarski et al., 2023), potentially leading to a decrease of the temperature lapse rate. However, it remains unclear if such elevation dependent warming has happened during previous interglacials. Therefore, reconstructing temperature lapse rate estimates from past warm intervals offer a unique opportunity to investigate if elevation dependent warming has occurred in the past and whether we are to expect such a process in the future.
In order to examine the past temperature lapse rates, we used speleothem samples from caves collected along an altitudinal transect from the Jura mountains to the Swiss Alps. The speleothems contain past drip water that has been preserved in micrometric sized fluid inclusions (0.01 to 0.1 weight %). This drip water corresponds to precipitation water falling above the cave and thus constitutes an excellent archive of past precipitation (Affolter et al., 2025). By combining the stable isotopic compositions of speleothem fluid inclusion waters and calcite, absolute paleotemperatures can be estimated.
Here we present temperature lapse rates of the Northern Alpine region based on speleothem fluid inclusion water from the mid Holocene and the Marine Isotope stage 5 (MIS 5) intervals. Overall, ~140 fluid inclusions samples obtained from 18 stalagmites from 12 caves situated along a transect from the Jura mountains to the Swiss Alps, across elevations ranging from 373 to 1’890 meters.
Preliminary results indicate that very slight elevation dependent warming might have occurred. However, especially for MIS 5, mountain uplift and erosion may significantly impact the temperature lapse rate as cave elevations have changed over time, increasing uncertainties. The average paleotemperatures show that modern air temperatures are ~1°C to ~1.5°C warmer compared to the mid Holocene.
How to cite: Kipfer, T., Fleitmann, D., Häuselmann, A., Hofmeister, E., Held, F., Luetscher, M., Cheng, H., and Affolter, S.: Northern Alpine temperature lapse rates from the mid Holocene and MIS 5 based on speleothem fluid inclusions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20247, https://doi.org/10.5194/egusphere-egu26-20247, 2026.
Cueva Victoria is located in the semi-arid region of south-eastern Spain, one of the driest regions in Europe with mean annual precipitation of 200–300 mm and pronounced seasonality. The cave is hosted in Triassic dolomites and limestones of the Alpujarride Complex, part of the Inner Betic Cordillera, where karstification has enabled the development of extensive cave systems and flowstone formation. These flowstone deposits provide a sensitive archive of past climate variability.
Previous studies established robust ²³⁰Th/U chronologies spanning the last ~450 ka, demonstrating that speleothem growth occurred during both interglacial and warmer glacial periods, such as Marine Isotope Stage (MIS) 3, reflecting phases of enhanced regional moisture availability.
Here, we investigate flowstone samples VIC-III-4 and VIC-III-5, covering MIS 11c to MIS 7a (~430–190 ka), to evaluate their potential as quantitative paleotemperature archives. Preliminary nucleation-assisted (NA) fluid inclusion microthermometry measurements of a few flowstone samples yielded cave temperature estimates in agreement with the range of independently derived TEX₈₆-based temperature reconstructions from the same samples.
Detailed petrographic thin section analysis of the two flowstones indicates the presence of several fluid-inclusion-bearing growth layers that appear promising for NA fluid inclusion microthermometry. This provides the basis for targeted selection of additional microthermometry measurements and a more detailed analysis of the two flowstones. Although assisted (NA) fluid inclusion microthermometry has successfully been applied to speleothems from other regions, this study represents the first application to the Cueva Victoria flowstones and one of the first applications to a semi-arid cave system.
The combination of precisely dated high-resolution speleothem proxy records (stable isotopes, trace elements) with direct temperature reconstructions significantly enhances the potential of the Cueva Victoria flowstones for palaeoclimate reconstruction and will contribute to improving terrestrial paleoclimate reconstructions for the western Mediterranean region, an area highly sensitive to future hydroclimate change.
How to cite: Burck, J., Weber, M., Meckler, A. N., Krüger, Y., Vonhof, H., Martinez-Garcia, A., and Scholz, D.: Quantitative paleotemperature reconstruction from Cueva Victoria speleothems using nucleation-assisted fluid inclusion microthermometry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12750, https://doi.org/10.5194/egusphere-egu26-12750, 2026.
Speleothems represent high-resolution continental archives that provide important information about past climate and paleo environmental changes. Their suitability for uranium-thorium dating enables the development of precisely constrained chronologies. Speleothems often contain small amounts of paleo drip water, which was trapped in the stalagmite fabric during the time of formation. The fluid inclusion oxygen (δ18Ofi) and hydrogen (δ2Hfi) coupled to the calcite δ18Ocalcite stable isotopes can be used for the reconstruction of absolute mean annual paleo temperatures. For our study site realm in Switzerland, δ18Ocalcite was often suggested to be interpreted as a temperature signal, at least during warm intervals such as the Holocene. However, δ18Ocalcite patterns are not able to provide absolute temperature estimates and can be controlled by several factors such as precipitation amount, temperature, and moisture source. Decoupling between δ18Ocalcite evolution and temperature signal can be clarified by comparing with an unambiguous temperature record based on a strong chronology and from the same realm. Such temperature records are scarce for the Central European lowland realm. The existing records are essentially based on biogenic proxies, which are summer biased and where dating can be sometimes difficult.
In this study, we present a new absolute mean annual paleotemperature record for the Central European realm based on fluid inclusion stable isotopes from two Milandre caves (Switzerland) stalagmites. As demonstrated in previous studies conducted within this cave, δ2Hfi has been shown to function as a key proxy for the reconstruction of mean annual paleotemperatures for the central European low elevation realm (Affolter et al. 2019). Here we provide temperature snapshots for the glacial – interglacial transition starting at the penultimate glacial maximum (MIS6) with an average temperature of ca. 4°C until the thermal maximum (MIS5). During MIS6 and the following transition, δ18Ocalcite pattern is decoupled from the temperature evolution. In order to shed light on the δ18Ocalcite interpretation, we discuss the evolution of two high resolution δ18Ocalcite pattern measured on the same stalagmites as the temperature snapshots. With the δ18Ocalcite/temperature comparison we suggest that δ18Ocalcite of the Milandre cave does not represent atmospheric temperature fluctuations during the examined time span. Instead, δ18Ocalcite likely provides information about the moisture source and its changes during the glacial period and the following transition.
How to cite: Hofmeister, E., Fleitmann, D., Häuselmann, A., Cheng, H., Kipfer, T., and Affolter, S.: Absolute paleotemperature evolution for MIS6 – MIS5 transition and moisture source changes based on Central European stalagmites, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20339, https://doi.org/10.5194/egusphere-egu26-20339, 2026.
Understanding continental climates across multiple glacial-interglacial cycles remains fundamentally limited by the scarcity of continuous, high-resolution terrestrial archives. During glacial periods, many terrestrial records are interrupted by prolonged depositional hiatuses. Although Greenland ice cores provide exceptional high-resolution records, they reach back only about 128,000 years, leaving earlier key climate intervals poorly constrained. Here, we present a composite record of subglacial speleothems from the European Alps spanning nearly half a million years (0-450 ka BP), providing a quasi-continuous, high-resolution record of continental climate variability supported by well-constrained chronologies.
Alpine and subglacial speleothems offer a unique paleoclimate window because they record both interglacial warmth during conventional growth phases and glacial conditions during deposition beneath ice cover, thereby capturing the full range of Quaternary climate states within a single archive type. Our Alpine composite reveals coherent oxygen isotope patterns across multiple cave systems and elevational gradients, reflecting regional-scale changes in temperature, precipitation, and moisture sources over five glacial-interglacial cycles.
Millennial-scale variability persists throughout the entire 450,000-year record, suggesting that rapid climate oscillations—often considered characteristic of the last glacial cycle—are instead a persistent feature of Quaternary glaciation dynamics. Orbital-scale forcing is clearly expressed across all cycles, albeit with notable deviations from the hemispheric trend. Most critically, beyond 250 ka BP, Alpine climate dynamics increasingly decoupled from global ice-volume signals while showing a strengthened coherence with global greenhouse gas concentrations.
Based on 37 speleothem records from 10 caves, this composite demonstrates that alpine and subglacial speleothems represent a transformative but underutilized terrestrial climate archive. Their ability to bridge the temporal gap between ice-core and marine records, combined with sub-millennial resolution and exceptional chronological control, opens new possibilities for reconstructing and understanding terrestrial climate evolution across extended Quaternary timescales.
How to cite: Honiat, A., Baker, J., Honiat, C., Luetscher, M., Moseley, G., Fohlmeister, J., and Spötl, C.: 450,000 Years of Climate Variability: A Speleothem Composite from the Northern European Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20606, https://doi.org/10.5194/egusphere-egu26-20606, 2026.
Quantitative paleotemperature reconstructions of the Holocene are crucial for understanding the evolution of the climate system in response to various natural and anthropogenic forcings and shed further light on the so-called “Holocene temperature conundrum” (Liu et al., 2014). In the eastern Mediterranean – Black Sea (EMBS) region, records of Holocene temperature variations in continental interiors are predominately based on palynological reconstructions, specifically, pollen records from lake and peat sediments (e.g., Davis et al., 2003). However, vegetation was severely compromised by human activities since the mid-Holocene period and possibly even earlier (e.g., Fyfe et al., 2018) causing uncertainties regarding the general temperature development over the course of the Holocene. In contrast to these biological paleoclimate archives, quantitative paleotemperature reconstructions can be provided by speleothem fluid inclusions (e.g., Affolter et al., 2019; Bernal-Wormull et al., 2025). Speleothems from Sofular Cave in northern Türkiye are known to be highly sensitive to climatic shifts on orbital to decadal timescales (Fleitmann et al., 2009; Held et al., 2024, 2025), making them an excellent archive for recording Holocene low-amplitude climate change.
Temperature estimates based on fluid inclusion isotope analysis average 11.7 ± 2.6°C for the mid- to late-Holocene period, which is almost identical with the modern cave air temperature of 11.8 ± 0.2°C. Overall, temperatures decrease by approximately 1.5°C from the mid- to late-Holocene (~7 ka – 3 ka BP), most likely related to orbital forcing and altering atmospheric circulation patterns in the EMBS region. The Sofular speleothem record also captures distinct temperature minima associated with the 4.2 ka event and the Little Ice Age. Both time intervals are characterized by a cooling of around 1-3°C within decades, although they differ in hydrological conditions, exhibiting wetter conditions during the 4.2 ka event and a dry period during the Little Ice Age in the Black Sea region.
References
Affolter et al., 2019: Central Europe temperature constrained by speleothem fluid inclusion water isotopes over the past 14,000 years, Science Advances, 5.
Bernal-Wormull et al., 2025: Temperature variability in southern Europe over the past 16,500 years constrained by speleothem fluid inclusion water isotopes, Climate of the Past, 21, 1235-1261.
Davis et al., 2003: The temperature of Europe during the Holocene reconstructed from pollen data, Quaternary Science Reviews, 22, 1701-1716.
Fleitmann et al., 2009: Timing and climatic impact of Greenland interstadials recorded in stalagmites from northern Turkey, Geophysical Research Letters, 36 (19), L19707.
Fyfe et al., 2018: Trajectories of change in Mediterranean Holocene vegetation through classification of pollen data, Vegetation History and Archaeobotany, 27, 351-364.
Held et al., 2025: Hydrological variability in the Black Sea region during the last 670,000 years recorded in multi-proxy speleothem records from northern Türkiye, Quaternary Science Reviews, 367, 109534.
Held et al., 2024: Dansgaard-Oeschger cycles of the penultimate and last glacial period recorded in stalagmites from Türkiye, Nature communications, 15(1), 1183.
Liu et al., 2014: The Holocene temperature conundrum, Proceedings of the National Academy of Sciences, 111(34), E3501-E3505.
How to cite: Held, F., Cheng, H., Edwards, R. L., Kipfer, T., Tüysüz, O., Affolter, S., and Fleitmann, D.: Holocene temperature variability in the Black Sea region recorded by speleothem fluid inclusions from Sofular Cave in northern Türkiye, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3142, https://doi.org/10.5194/egusphere-egu26-3142, 2026.
The modern Western Mediterranean climate is characterised by strong seasonality and, especially in south-eastern Spain, by limited rainfall. In contrast, terrestrial and marine archives indicate that the peak of the last interglacial was marked by warmer conditions and potentially more variable climate, partly driven by meltwater outbursts in the North Atlantic. High insolation during interglacials forced a northward displacement of the Intertropical Convergence Zone, increasing rainfall over Northern Africa. Enhanced fluvial input leads to stratification of the Eastern Mediterranean Sea and ultimately to the deposition of sapropels. However, the climatic consequences of these large-scale processes for south-eastern Iberia have not yet been systematically investigated.
Several speleothems from Cueva Victoria, south-eastern Spain, cover the mid-Pleistocene to the Holocene. During the last glacial period, Dansgaard/Oeschger (D/O)-type variability is expressed in the speleothem stable isotope records. Variations in speleothem stable isotope values are interpreted in terms of changes in temperature (δ18O) and vegetation cover (δ13C). In general, warmer temperatures during D/O events are associated with lower δ18O values due to temperature and moisture source effects. Increased effective precipitation (precipitation-evaporation) is reflected by more negative δ13C values, resulting from higher soil microbial activity and denser vegetation cover.
Here, we present a compilation of speleothem records from Cueva Victoria spanning several interglacials and encompassing the timing of multiple sapropel layers in the Eastern Mediterranean. A comparison of speleothem stable isotope signatures during the formation of different sapropels reveals contrasting climatic responses in south-eastern Spain. During glacial phases, speleothem growth coincided with the timing of the sapropel deposition, indicating more humid conditions in south-eastern Spain. In contrast, during the Holocene Climate Optimum and the formation of sapropel 1, elevated δ13C values point to a decline in vegetation cover, interpreted as a result of enhanced seasonality. Speleothem formation is almost completely absent during sapropel 5 (≈ 122-128 ka), which may reflect enhanced seasonality with warmer temperatures associated with a reduction in precipitation-evaporation compared to the Holocene.
How to cite: Budsky, A., Scholz, D., Spötl, C., Weber, M., and Vonhof, H.: A climatic link between speleothem formation in south-eastern Spain and Eastern Mediterranean sapropel deposition?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17746, https://doi.org/10.5194/egusphere-egu26-17746, 2026.
There is strong evidence that cyclical changes to Earth’s orbital configuration during the Pleistocene led to the periodic greening of vast areas of the Sahara, East African Rift Valley, and Arabia. The opening of these humid corridors facilitated the dispersal of humans out of eastern Africa into Asia and beyond. However, less is known about what happened under opposite circumstances, when these corridors dried up due to waning orbital forcing. One hypothesis is that human populations sought refuge in eastern Africa’s coastal forests when conditions in the African interior were inhospitable. We test this hypothesis by evaluating the stability of climate in coastal Kenya from our reconstruction vis-à-vis climate in the African interior from previously published work. Speleothem samples collected from limestone quarries near Mombasa and Kilifi provide a novel record of long-term climate change in eastern Africa and offer new insight into human biogeography. Preliminary U-Th age results suggest that these samples grew throughout the last glacial period and possibly during older glacial-interglacial cycles. This sustained growth indicates that eastern African coastal climate was characterized by stable conditions and a positive moisture balance, supporting the refugia hypothesis. To further constrain the climate dynamics governing coastal eastern Africa, temperature and hydroclimate reconstructions are being developed using fluid inclusion and TEX86 analyses.
How to cite: Tiger, B., Nicholson, S., Ndiema, E., Kinyanjui, R., van der Lubbe, J., Haug, G., Scholz, D., Weber, M., and Vonhof, H.: Reconstructing coastal eastern African climate from speleothems: Implications for human biogeography, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20349, https://doi.org/10.5194/egusphere-egu26-20349, 2026.
Green periods are becoming an increasingly important facet of both understanding the climatic evolution of Arabia, and permitting mammal dispersals between Africa and Eurasia. Recent research from central Arabia has shown that recurrent phases of increased monsoonal rainfall extended back into the Miocene. However, the latitudinal extent of the tropical rainbelt and green environments, especially at potential dispersal entry points into Arabia, remains uncertain. Here, we provide information on the timing of northern Arabian pluvial periods over the last 10.5 million years. We applied U-Pb dating to a new set of 50 speleothems from 5 caves, showing that periods of enhanced rainfall occurred between ~1.2 to ~1.7 Ma, ~2.8 to ~3.7 Ma, ~4 to ~7.5 Ma and ~9.8-10.5 Ma. Speleothem fluid inclusion water δ18O and δD stable- sotopes plot in excellent agreement with monsoonal precipitation sources, indicating the tropical rainbelt migrated to at least 29°N over Arabia in Mio-Pleistocene green phases. Absence of speleothem deposition in northern Arabia following the Mid-Pleistocene Transition (1.2 Ma) indicate monsoonal rainfall did not reach high latitudes in sufficient amounts, and reveal a time-transgressive reduction in the northward extent of monsoonal rainfall. These highlight the role of enhanced glacial-boundary conditions as a suppressant to the northern extent of rainfall during green Arabia periods. Whilst Mid-Late Pleistocene lacustrine evidence indicates increased rainfall compared to modern climates, our data suggest that mammal (especially hominin) dispersals in this region took place during relatively drier pluvial periods compared to the Mio-Pliocene.
How to cite: Nicholson, S., Vonhof, H., Groucutt, H., Breeze, P., Drake, N., Al Jibreen, F., Stewart, M., Markowska, M., Sholz, D., Weber, M., Gerdes, A., Martinez-García, A., Petraglia, M., and Haug, G.: Pluvial periods in northern Arabia over the last 10 million years, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11483, https://doi.org/10.5194/egusphere-egu26-11483, 2026.
The Arabian Desert experienced multiple periods of wetter and greener conditions that sustained human populations and allowed the dispersal of mammal fauna across the Arabian Peninsula. A recently published speleothem-based paleoclimate reconstruction of central Arabia extends the record of such recurrent short-lasting humid periods over at least the past 8 million years. Here, we applied multiple recently developed paleothermometers to this late Miocene to late Pleistocene speleothem record: Fluid inclusion stable isotopes, microthermometry and dual-clumped isotopes. The data indicate that in the late Miocene and Pliocene, wetter episodes in central Arabia were up to ~4 °C warmer than current Mean Annual Air Temperature (MAAT). These temperature estimates imply that potential evapotranspiration was significantly higher during the late Miocene and Pliocene than during the late Pleistocene. From these temperature estimates, we calculated Pliocene potential evapotranspiration and estimated precipitation amounts for the humid periods in central Arabia. All the evidence from the speleothems combined (temperature, precipitation, δ¹³C values) suggests that over the past 8 million years, the wetter phases in central Arabia typically led to savanna-like environments.
Modern climate data show that our study area has already reached Pliocene MAATs in recent years due to anthropogenic warming. The concomitant drying trend in modern settings indicates that higher temperatures are not the key factor in creating wetter conditions on the Arabian Peninsula. Previously proposed orbital control on the incursion of monsoonal moisture from the south into the Arabian Peninsula remains the most important driver of humidity during these past humid periods. In the modern orbital configuration, monsoonal moisture advection is displaced to the south, and increasing temperatures will likely lead to increased potential evaporation and aridity in central Arabia.
How to cite: Schröder, J., Vonhof, H. B., Scholz, D., Meckler, A. N., Markowska, M., Nicholson, S. L., Weber, M., Martinez-Garcia, A., Krüger, Y., Fiebig, J., and Haug, G.: Exploring past environments based on temperature reconstructions from Pliocene Arabian speleothems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20601, https://doi.org/10.5194/egusphere-egu26-20601, 2026.
Over the last decades, several new methods for quantitative paleo-temperature reconstructions with stalagmites have emerged, further enhancing the value of these powerful paleoclimate archives. Among these innovative stalagmite-based thermometers, fluid inclusion microthermometry (Krüger et al., 2011) is often regarded as the most precise and accurate method (Meckler et al., 2015), but its applicability is restricted to formation temperatures > 10 °C, specific calcite fabrics, and abundant fluid inclusions of appropriate size. Fortunately, other temperature proxies have been proposed that each have different strengths and weaknesses, allowing us to compensate for the limitations of individual methods. Many of them, including fluid inclusion water isotopes and TEX86, are still under active development, with substantial uncertainties remaining in their interpretation (e.g., Affolter et al., 2025; Baker et al., 2019). Applying multiple temperature proxies to the same stalagmite allows a direct comparison of proxy behavior, providing improved constraints on the reconstructed paleoclimate variability.
In this study, we reconstruct tropical temperature using stalagmite GC08 from northern Borneo, which spans multiple glacial cycles. Here we investigate the oldest part from approximately MIS 14 to MIS 11 (ca. 570 ka to 360 ka), which covers the Mid-Brunhes Transition (MBT; Yin, 2013) at the end of MIS 12. The MBT marks a fundamental change in the climate system with a significant increase in the amplitude of the glacial-interglacial cycles observed in various climatic archives (e.g., Barth et al., 2018). We use three different temperature proxies for the reconstruction: fluid inclusion microthermometry, fluid inclusion water isotopes, and TEX86. Our records reveal notably different temperature trends among the three proxies. Both fluid inclusion microthermometry and TEX86 indicate surprisingly little temperature change across the study interval. We note that the fabric is not ideal for fluid inclusion microthermometry, as large intervals are characterized by biogenic influence and/or diagenesis, which limit the applicability and accuracy of the method. TEX86 seems to be influenced by soil-derived compounds in part of the stalagmite. Fluid inclusion water isotopes appear to be affected by large evaporation or other fractionating effects, as indicated in a cross-plot of oxygen and hydrogen isotopes. Correction attempts do not yield realistic temperatures, with an unrealistically large amplitude of 20 °C. These findings highlight the limitations of individual stalagmite-based paleo-thermometers and emphasize the critical role of depositional context in their interpretation. We therefore call for caution when interpreting single-proxy temperature evidence in the absence of constraints on in-cave processes in future stalagmite-based paleo-temperature studies.
How to cite: Ding, H., Krüger, Y., Maccali, J., Martínez-García, A., Pasqualetto, L., and Meckler, A. N.: Multi-proxy temperature records from a northern Borneo stalagmite reveal sample-specific challenges, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20944, https://doi.org/10.5194/egusphere-egu26-20944, 2026.
For speleothems found in the Asian Monsoon region, variability in oxygen isotopes (18O) over time is often taken as an indicator of changes in monsoon intensity. In regions affected by both the summer and winter monsoons the picture is more complex, as each system may have its own mechanism for driving changes in rain 18O. To try to tease out the possible drivers behind changes in 18O, published speleothem records from a region of Southern Thailand are compared to over a decade of daily rainfall 18O measurements. When comparing winter and summer monsoon isotope averages, the seasonal difference is found to be too small to explain the changes seen in speleothems over the past several thousand years. This suggests a simple change in monsoon ratio is unlikely to be a direct driver. However, there is a strong indication that periodic intense winter monsoon pulses show a distinct isotopic signature. This signature is sufficient to explain past variability, and by extension suggests that speleothem 18O records from the locality mostly reflect changes in the winter monsoon system. We explore possible mechanisms driving these 18O-light pulses and what they suggest about the past climate configuration in the region.
How to cite: Kontsevich, G., Duerrast, H., Liang, M.-C., Jirapinyakul, A., Chawchai, S., Phanindra, A., Oza, H., and Lowemark, L.: Daily rainfall δ18O suggests Southern Thailand speleothem 18O records controlled by extreme winter monsoon events, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4850, https://doi.org/10.5194/egusphere-egu26-4850, 2026.
The ‘4.2 ka event’ (~4200–3900 yr BP) is now a globally-recognised Holocene chronostratigraphic marker, delineating the boundary of the middle-to-late Holocene1. First identified as a drought signal corresponding to ~2200 BCE in the Tell Leilan stratigraphy (Syria), correspondence between this signal and the collapse of the Akkadian empire was interpreted as sign of a causal association, and one of the first explicit links made between a major climate shift and civilizational transformation2. Several studies have more recently presented evidence suggesting this drought was in fact a globally-pervasive phenomenon, linked to the decline of the ancient Egyptians, the de-urbanization of the Harappans, and the demise of the Neolithic Culture of China3,4,5. However, no clear consensus exists on whether the 4.2-kyr event was truly global in scale, nor whether the event was consistently marked by aridity6,7. But perhaps most critically, it is unclear whether a clear drought signal at 4.2-ka2 occurs consistently in paleoclimate records across southwest Asia8. Without a clear perspective on if, and how, regional climate signals relate to one another across this interval, it is difficult to ascertain whether changes occurring at ~4.2 ka are mechanistically distinguishable from internal noise in a highly sensitive, and complex climate system9. To address this uncertainty, we present a first look at new stable isotope, trace element, and fluid inclusion measurements from speleothems grown in Kuna Ba and Shalaii Caves (~400 km SE of Tell Leilan) in Iraqi-Kurdistan. By combining these results with published geochemical data from paleoclimate archives across southwest Asia, we will assess whether the hydro climatic changes recorded in these archives capture a distinct anomaly corresponding to the 4.2-ka event. Hence, providing a chronologically-robust framework with which to assess the regional-scale timing, expression, and coherence of climate variability before, during, and after the proposed 4.2-ka event.
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1Walker et al. (2018) Episodes 41(4): 213-223 ; 2Weiss et al. (1993) Science 261 (5124): 995-1003 ; 3Weiss & Bradley (2001) Science 291(5004): 609-610 ; 4Carolin et al. (2019) PNAS USA 116(1): 67-72 ; 5Zhang et al. (2021) Science Advances 7(48): 1-9 ; 6McKay et al. (2024) Nature Communications 15: 6555 ; 7Nan et al. (2025) Earth-Science Reviews 265: 105128 ; 8Finné et al. (2011) Journal of Archaeological Science 38: 3153-3173 ; 9Zittis et al. (2022) Reviews of Geophysics 60: e2021RG000762.
How to cite: Paine, A., Altaweel, M., Parvizi, P., Held, F., Affolter, S., Raible, C., Djamali, M., Cheng, H., and Fleitmann, D.: Is the 4.2-ka event visible in speleothem records from southwest Asia?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13872, https://doi.org/10.5194/egusphere-egu26-13872, 2026.
The Indo-Pacific Warm Pool (IPWP), a region in the western Pacific Ocean known as the “heat engine of the globe”, is critical for modulating global climate patterns. Tropical island nations within the IPWP are especially well suited to study how the IPWP will respond to anthropogenic climate change. To understand the effects of future climate change within the IPWP, it is useful to look to past rapid climate change events, like Heinrich Events, which were periods of Northern Hemisphere freshwater forcing. Despite the critical role that paleoclimatic studies of Heinrich Events play in constraining the effects of future climate change, there are few terrestrial paleoclimate records from within the IPWP focusing on these events.
Here, we use speleothems from the Puerto Princesa Underground River cave (PPUR) in Palawan, Philippines to reconstruct rainfall patterns during Heinrich Events. We present a combined record of δ18O, δ13C and trace elements (Mg/Ca, Sr/Ca, and Ba/Ca) for two stalagmites (GP-0 and GP-1) from PPUR’s Gaia Passage. GP-0 is 10.5 cm in length and grew between 41,855 ± 1099 to 31,637 ± 280 years B.P. (±2𝜎). GP-1 is 12.5 cm in length and grew between 40,849 ± 272 to 20,914 ± 206 years B.P. (±2𝜎). Taken together, our partially replicated record spans 41.9 to 20.9 ka and provides a robust dataset highlighting the effects of Heinrich Events 2, 3, and 4 on the southwestern Philippines and IPWP. Preliminary δ18O results show approximately 1.5 ‰ variability, suggesting fluctuations between wetter and drier intervals through time. In addition, statistically significant co-variation between Mg/Ca, δ18O, and δ13C indicates that prior calcite precipitation influences the GP-0 and GP-1 records. Additional statistical analyses between the geochemical results of GP-0 and GP-1 during coeval periods of growth will provide a strong understanding of the mechanisms driving rainfall in the Philippines during periods of rapid climate change. Regional comparisons to other archives (speleothems, marine core records) will help to elucidate the ocean-atmosphere feedbacks driving rainfall variability within the IPWP. A comparison to iTRACE climate model output across Heinrich Event 1 will broaden our understanding of the regional hydroclimate response to high latitude forcing. Furthermore, these results will inform much needed policy for water resource management and effective climate adaptation and resilience in the tropics.
How to cite: Hart, M., Senan, S., Yambing, J., Geraldes Vega, M., Belanger, B., Kong-Johnson, C., Geronia, M., Jalandoni, S., David, C. P., Oster, J., McGee, D., Ibarra, D., and Sekhon, N.: Using stalagmite geochemistry to reconstruct paleoclimate in the Philippines during Heinrich Events, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-837, https://doi.org/10.5194/egusphere-egu26-837, 2026.
Marine Isotope Stage 7 (~243-191 ka BP) represents a complex interglacial period characterised by multiple climate substages and gradual orbital forcing changes, culminating in one of the most rapid glacial inceptions of the Pleistocene at the MIS 7-6 transition (~201-187 ka BP). Despite its importance for understanding monsoon responses to glacial inceptions under differing orbital configurations, monsoon dynamics during this interval remain poorly understood due to a paucity of high-resolution paleoclimate records from Southeast Asia.
We present a multiproxy speleothem record from Boi Cave in northern Vietnam spanning 201-187 ka BP. In contrast to characteristic glacial-interglacial δ¹⁸O shifts observed at other Asian monsoon sites, our record exhibits minimal amplitude change across the MIS 7-6 transition. The δ¹⁸O signal instead preserves sustained high-frequency variability throughout the interval. Trace element geochemistry, however, documents clear local hydroclimate changes, with peak wet conditions at 197 ka and rapid monsoon reorganisation at ~191.4 ka. These hydroclimate changes align with glacial inception timing in other Asian speleothem records and correlate with North Atlantic and Mediterranean records, suggesting hemispheric-scale reorganisation of atmospheric circulation. Modern climate analysis reveals this region receives rainfall from both the Southwest Summer Monsoon and the Northeast Winter Monsoon systems during the soil recharge period, with the balance between moisture sources varying interannually.
We discuss how stable isotope and trace element proxies record different aspects of monsoon dynamics at this site. While trace elements document local infiltration in response to monsoonal rainfall, δ¹⁸O reflects the balance between Indian Ocean and Pacific moisture sources. This distinction arises from Boi Cave's unique geographical position, where both monsoon systems contribute to annual rainfall. This high-resolution reconstruction fills a critical spatiotemporal gap in understanding Southeast Asian monsoon dynamics during the penultimate glacial inception.
How to cite: Riviera, C., Breitenbach, S. F. M., Wolf, A., Longman, J., Standish, C. D., Jost, A. B., McGee, D., Rabett, R. J., Khanh, P. S., Trinh, A. D., and Ersek, V.: Moisture Source Dynamics during the Penultimate Glacial Inception (MIS 7-6) in Northern Vietnam Stalagmite, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19071, https://doi.org/10.5194/egusphere-egu26-19071, 2026.
Past interglacial periods with climatic conditions comparable to those of today, but shaped by different orbital configurations and greenhouse gas concentrations, provide valuable insights into natural climate variability. This project aims to address a major data gap in the highly heterogeneous tropics by developing a long, continuous, and high-resolution multi-proxy stalagmite record from the well-monitored Cueva Larga in Puerto Rico1. High-precision 230Th/U dating shows that this stalagmite archive enables a comprehensive comparison of interglacial periods over the last 300,000 years, covering MIS 1, MIS 5 (127 ka to 54 ka), MIS 7 (255 ka to 190 ka) and MIS 9 (310 ka to 280 ka).
We present multiple high-resolution time series of trace elements (Mg, P, Cu, Sr, Ba, U) obtained using LA-ICP-MS. Because the archive integrates data from several stalagmites, it is essential to account for in-cave variability, including effects of prior carbonate precipitation and CO2 exchange. These processes are evaluated through parallel growth phases of the stalagmites and in combination with stable carbon and oxygen isotopes. Here, we focus on the rigorous evaluation of the LA-ICP-MS trace-element records to ensure a reliable and reproducible reconstruction at decadal resolution.
Time-series analyses of this new composite multi-proxy dataset are expected to enhance both qualitative and quantitative understanding of interglacial environmental change, particularly with respect to precipitation intensity and variability. Ultimately, this work will improve assessments of tropical climate sensitivity to external forcing and provide critical context for evaluating the magnitude of ongoing climate change relative to natural variability.
1 Warken et al. (2020). Persistent Link Between Caribbean Precipitation and Atlantic Ocean Circulation During the Last Glacial Revealed by a Speleothem Record from Puerto Rico. Paleoceanography and Paleoclimatology, Vol. 35, No. 11, https://doi.org/10.1029/2020PA003944
How to cite: Mielke, A., Lövenich, F., Garcia, N., Charles, C., Keppler, F., Rivera Collazo, I., Acosta-Colón, Á. A., Winter, A., Spötl, C., and Warken, S.: Tropical Climate Variability During Interglacials of the Last 300,000 Years: Evaluation of High-Resolution LA-ICP-MS Trace-Element Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11197, https://doi.org/10.5194/egusphere-egu26-11197, 2026.
Reconstructing past temperature variations is essential for understanding climate systems and improve projections for future climate changes. In central-east South America, modern warming has been shown to progress faster than global average. Nonetheless, paleotemperature records remain sparse in central South America, which limits our ability to evaluate the response of this region to rapid shifts in global forcings, such as during the deglacial period. Studies show that temperature evolution during the deglaciation was characterized by high-latitude rapid warming episodes associated with major reorganizations of the Atlantic Meridional Overturning Circulation (AMOC), which led to perturbations in inter-hemispheric heat distribution. Yet, how these perturbations affect temperatures in tropical South America and the thermal evolution of this region is still largely unknown. Here we present a new 15k-year paleotemperature reconstruction from a precisely dated speleothem collected in central-eastern Brazil. The temperature record is based on the glycerol dialkyl glycerol tetraether (GDGT) paleothermometer, revealing a total of 6.1°C±0.81 (2std = 0.81°C) of temperature shifts over the last 15k years. Our findings provide evidence of a non-linear temperature increase since the last deglaciation with abrupt warming and cooling events in response to high-latitude forcings, shifts in South Atlantic sea-surface temperatures (SSTs), and increases in atmospheric CO2. Finally, we present a temperature gradient within central-east Brazil and show how paleoclimate models might underestimate rapid temperature changes.
How to cite: Della Libera, M. E., Cauhy, J., Novello, V., Ampuero, A., Cruz Junior, F. W., Stríkis, N., Martínez-García, A., Vonhof, H., and Scholz, D.: Tropical South American temperature responses to rapid high-latitude climate shifts since the last deglaciation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20937, https://doi.org/10.5194/egusphere-egu26-20937, 2026.
New high-resolution trace element records combining stalagmites from Southeastern Brazil (SEBRA) evidence persistent multi-centennial shifts in hydroclimate conditions over the past 7,500 years, with wet anomalies associated with North Atlantic cooling events, including Bond events and the Little Ice Age (LIA). Our analysis reveals a coupling between the Bond events and increased South Atlantic Convergence Zone (SACZ) rainfall over SEBRA, with a persistent pattern over the Middle and Late Holocene. The most pronounced wet anomalies in SEBRA are synchronous with these events, and present a coherent structure with other records from the South American Summer Monsoon (SASM) region and the SACZ, and are in antiphase with Southern Brazil (SB) resembling the multi-centennial dipole between SEBRA and SB. This pattern indicates that large-scale reorganizations of the Intertropical Convergence Zone (ITCZ) are induced by North Atlantic cooling and a strengthened SASM/SACZ convection through changes in cross-equatorial heat transport related to a weakening of the AMOC. Furthermore, the interhemispheric antiphase relationship between SEBRA wet anomalies and drying across the Asian monsoon region evidences the global expression of AMOC–ITCZ modulation under North Atlantic cooling events. These findings demonstrate the pronounced response of SEBRA hydroclimate to even modest perturbations in the interhemispheric energy balance, evidencing the sensitivity of the region towards potential impacts under AMOC weakening scenarios.
How to cite: Cauhy, J., Della Libera, M. E., M. Stríkis, N., Bernal, J. P., Vuille, M., W. Cruz Junior, F., Edwards, R. L., F. Novello, V., Vonhof, H., and Scholz, D.: Multi-centennial hydroclimate shifts of Southeastern Brazil hydroclimate in response to North Atlantic cooling events over the past 7,500 years, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20503, https://doi.org/10.5194/egusphere-egu26-20503, 2026.
Disentangling dominant patterns and underlying drivers of hydroclimate variability and tropical cyclone activity in the tropical Americas remains a challenge of paleoclimatology. To explore the potential of speleothem trace metal abundances to close this gap, we study a fast-growing stalagmite from Xplor Cave from Mexico's Yucatán Peninsula. High precision 230Th/U dating with average uncertainties of 5-6 years combined with annual layer counting confine XPL04’s growth between c. 1590 to c. 1970. Due to exceptionally high growth rates between 1 and 4mm per year, the record allows to assess sub-annually resolved proxy variations from post-Colombian times into the 20th century.
Laser Ablation ICP-MS trace metal data from speleothem XPL04 indicate pronounced patterns in hydroclimate sensitive elements. For example, increasing Mg/Ca values suggest a significant drying trend along with a rise in hydroclimate variability during the 20th century. Furthermore, multiannual transition metal changes covary with long-term tropical cyclone activity. Superimposed on that pattern, Cu concentrations and Cu/Ni ratios peak during major hurricane years, with the most pronounced speleothem responses corresponding with the largest events that made landfall at the cave site (the 1933 ‘Tampico’ Hurricane and a 1903 unnamed event).
This preliminary evaluation encourages in-depth analyses of sub-annual to decadal speleothem trace element variations. Future work will include the integration of elemental and isotopic proxies in order to construct a precisely dated multi-proxy record allowing to assess regional hydroclimatic changes on unprecedented timescales.
How to cite: Warken, S., Wantzen, A., Mielke, A., Schorndorf, N., Lases Hernández, F., Avíles Olguín, J., and Frank, N.: Exploring sub-annual to decadal hydroclimate variability and tropical cyclone activity on the northeastern Yucatán peninsula , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10573, https://doi.org/10.5194/egusphere-egu26-10573, 2026.
Tropical rainfall is conventionally linked to orbital-scale insolation variability, with higher summer insolation corresponding to stronger precipitation. Yet speleothem d18O records from the greater Mesoamerican region show opposing behaviour (Lucia et al. (2024), Li et al. (2025)), hinting at other forcing mechanisms. Here, we present a precisely dated speleothem record from Puerto Rico covering the past 234,000 years, which is compared to isotope-enabled climate model time slice simulations. By combining our new data with speleothem data from northern Brazil we create climate indeces to assess local ITCZ position and width. The data-model comparison offers the opportunity for an orbital time scale analysis, where insolation is considered for different months and latitudes. Preliminary analyses indicate that the early-rainy season might play a bigger role than previously assumed. Furthermore, millennial-scale variability strongly characterises the proxy record, which cannot be attributed to orbital forcing, but suggests a persistent sensitivity to AMOC strength (compare Warken et al. (2020)). Future work will assess, why Caribbean hydroclimate appears to be not a classical monsoon system throughout MIS 7 to 1 but rather the result of multiple factors superimposing on different timescales.
References:
Lucia et al. (2024). Atlantic Ocean thermal forcing of Central American rainfall over 140,000 years. Nature communications. DOI: 10.1038/s41467-024-54856-0
Li et al. (2025). North Atlantic Subtropical High forcing of Atlantic Warm Pool hydroclimate variability on millennial to orbital timescales. Science Advances. DOI: 10.1126/sciadv.aea5042
Warken et al. (2020). Persistent Link Between Caribbean Precipitation and Atlantic Ocean Circulation During the Last Glacial Revealed by a Speleothem Record From Puerto Rico. Paleoceanography and Paleoclimatology. DOI: 10.1029/2020PA003944
How to cite: Lövenich, F., Mielke, A., Spötl, C., Werner, M., Acosta-Colón, Á., Rivera Collazo, I., Winter, A., and Warken, S.: Assessing millennial to orbital-scale controls of Caribbean hydroclimate variability via data-model-comparisons, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10789, https://doi.org/10.5194/egusphere-egu26-10789, 2026.
Many proxies reveal that the low-latitude precipitation varies at a periodic of ∼23 ka, which is governed by precessional forcing. Classical theory proposed that precession-induced increased summer insolation in the Northern Hemisphere (perihelion) corresponds to decreased summer insolation in the Southern Hemisphere (aphelion), hence, controlling the inter-hemisphere temperature contrast and driving the meridional shift of the ITCZ. Accordingly, the low-latitude precipitations are expected to be in-phase (for the Northern Hemisphere) or anti-phase (for the Southern Hemisphere) with the Northern Hemisphere summer insolation. However, in the past two decades, collective proxies showed that the low-latitude precipitation follows very different rhythms, very often out-of-phase with hemispheric summer insolation. For example, the Eastern Asian precipitation evolutes resembling the Northern Hemisphere summer insolation, whereas the Malaysian precipitation correlates the variations in October insolation. The mechanism driving this phenomenon has puzzled the paleoclimate community for more than two decades, however, remains elusive. In this study, by combining theoretical analysis, numerical simulations, and geological records, we proposed a new hypothesis, suggesting that the precession regulates the low-latitude precipitation by altering the latitude of perihelion. The “latitude of perihelion” is defined as the latitude of overhead Sun at the time of perihelion. We demonstrated that wherever (the latitude) and whenever (the season) perihelion occurs, the incoming solar radiation at the corresponding latitude reaches its maximum, driving the strongest land-sea temperature contrast and regional precipitation over land in the corresponding season. The perihelion occurs towards different latitudes and in different seasons depending on the precessional phase. Therefore, the precipitation at different latitudes naturally follow different rhythms.
How to cite: Yang, H.: Precession of the Earth's rotation axis drives naturally asynchronous precipitation variation at low-latitudes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21886, https://doi.org/10.5194/egusphere-egu26-21886, 2026.
