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A stalagmite was collected in northern Hungary from the Vacska Cave, where monitoring and ventilation-based site selection had been conducted. The stalagmite covers the 10–8 ka (relative to AD 1950) period, including the so-called 8.2 ka event, and showed preceding signs of climate change that were evaluated by petrographic observations, 14C activities, Sr concentrations, and stable isotope compositions of calcite and inclusion-hosted water. Comparisons of speleothem records show that isotope peaks at ca. 8.5 ka are related to a regional climate anomaly, rather than to a continental-scale event. In accordance with regional proxy records, the 8.2 ka event was associated with a series of temperature and precipitation amount changes, starting with cooling and a reduction in the winter-to-summer precipitation ratio, and then becoming a humid and warm phase at 8.15 ka. X-ray diffraction-based crystallinity parameter (FWHM) values provided evidence for diagenetic alteration of the stable oxygen isotope compositions of inclusion waters. Nevertheless, the stable hydrogen isotope compositions of inclusion waters and the oxygen isotope values of the host calcite revealed elevated d-excess values, and therefore increased Mediterranean moisture contribution during the 8.2 ka event, which indirectly indicate the southward displacement of moisture transport from the Atlantic Ocean.

Pollen preserved in caves provides a little-appreciated opportunity to study past vegetation and climate changes in regions where conventional wetland sediments are either unavailable, contain little organic matter, and/or are difficult to date accurately. Most palynology in caves has focused on clastic infill sediments, but pollen preserved in growing speleothems provides important new opportunities to develop vegetation and climatic records that can be dated accurately with radiometric methods. However, when pollen is present in speleothems, concentrations can vary by orders of magnitude, highlighting how little we know about the processes that transport pollen into caves and onto speleothem surfaces, and that determine the pollen's preservation probability. To explore these aspects of speleothem pollen taphonomy, we investigated the distribution of pollen and microscopic charcoal within several stalagmites from southwest Australia. We examined spatial patterns in pollen and charcoal preservation in order to distinguish whether observed gradients result from preservation or are products of systematic transport processes working along stalagmite surfaces. We find that pollen grains and charcoal fragments are located preferentially on the flanks of most stalagmites. This suggests that pollen grain and charcoal deposition on speleothems is influenced by transport and accumulation of detrital debris on growing surfaces. These insights will assist in future sampling campaigns focusing on speleothem pollen and charcoal contents.

The penultimate deglaciation was characterized by a sub-millennial-scale warm event in the Heinrich Stadial 11(HS11), termed the 134-ka event. However, its precise timing and structure remain poorly constrained due to the lack of high-resolution and precisely dated records. We present an oxygen isotope record of a speleothem with well-developed annual lamina from Zhangjia Cave, located on the north margin of the Sichuan Basin, characterizing Asian summer monsoon (ASM) changes in the 134-ka event, which included an increase excursion of ca. 149 years and decrease excursion of ca. 200 years, inferred from 3.3‰ δ18O variations. This event also divided the weak ASM interval-II (WMI-II), corresponding to HS11, into two stages, the WMI-IIa 132.8–134.1 ka and WMI-IIb 134.4–136.4 ka. With a comparable climatic pattern globally, the 134-ka event is essentially similar to the millennial-scale events in last glacial–deglacial period. Particularly, the observed weak-strong-weak ASM sequence (138.8–132.8 ka) is largely controlled by changes in the Atlantic Meridional Overturning Circulation (AMOC) forced by the meltwater of northern high-latitude ice sheets. Moreover, our results underpin that AMOC, rather than the global ice volume, is more critical to ASM variations during the last two deglaciations.

This study utilizes speleothem trace elements as climate proxies to reconstruct hydroclimate variability over approximately 350 years in the Southern Cook Islands. Stalagmites Pu17 and Pu4 from Pouatea cave were analyzed using high-resolution LA-ICP-MS for trace elements (Mg, Na, Sr, P, U, Y). By monitoring cave dripwater and conducting regression analysis, we found that Mg, Sr, and Na in Pouatea dripwater mostly originated from marine aerosols, while Sr and Ba were primarily from bedrock, with additional Ba coming from marine aerosols and weathered oceanic basalt leaching. Mg was identified as the most reliable element for hydroclimate reconstruction due to its predominantly marine aerosol origin. Infiltration, via dilution of marine aerosols and bedrock inputs, was identified as the main driver of trace element variations in Pouatea at a seasonal scale. Transfer functions were established between each trace element and effective infiltration was calculated, with Mg showing the strongest correlation. The reconstructed infiltration data were compared with climate indices, showing an overarching role of the SPCZ and ENSO in controlling rainfall in the South Pacific. This research demonstrates the potential of speleothem trace elements for paleohydroclimate reconstructions, improving understanding of rainfall variability in the climatically vulnerable South Pacific Islands over the past millennia.

Speleothem fluorescence can provide insights into past vegetation dynamics and stalagmite chronology. However, its origin and especially the formation of fluorescent laminations in stalagmites are poorly understood. We conducted a year-long monthly monitoring of drip water fluorescence in La Vallina Cave (northern Iberian Peninsula) and compared the results to drip water chemistry and active speleothems from the same sites. Drip waters were analyzed using fluorescence spectroscopy and parallel factor analysis (PARAFAC). The resulting five-component model indicates contributions from vegetation, microbial activity, and bedrock. Intra-site fluorescence variability is mainly influenced by changes in overlying vegetation, water reservoir time, and respiration rates. Contrary to prevailing views, we find no systematic increase in drip water fluorescence during rainy conditions across drip sites and seasonal variations in drip water fluorescence are absent at a location where present-day speleothem layers form. Our findings challenge the notion of a higher abundance of humic-like fluorescence during the rainy season as the primary cause for layer formation and suggest additional controls on drip water fluorescence, such as bedrock interaction and microbial reprocessing. We also propose that growth rate may control the dilation of the fluorescence signal in stalagmites, indicating other potential mechanisms for fluorescent layer formation.

This study presents the results of a detailed paleoclimate investigation on stalagmite YL-1 (Yelini Cave, Türkiye). YL-1 grew between 117.13 (+0.57/−0.44) ka and 114.87 (+1.63/−2.89) ka within Greenland Stadial 26, indicating a positive moisture balance during the stadial conditions in this semi-arid region. Rainfall is significantly affected by sub-cloud and surface evaporation and decreasing net effective winter precipitation is recorded by high isotope values. Enriched δ18O and δ13C at 116.65 (+0.51/−0.39) ka are interpreted as a drought event that took place ca. 400 years before the end of the MIS 5e. This event, which was reported simultaneously in marine and terrestrial archives in the Northern Hemisphere, is a result of decreased cyclone activity linked to weakening of the Atlantic meridional overturning circulation. 87Sr/86Sr values of YL-1 are close to the host-rock values. Decreased 87Sr/86Sr ratio at 116.67 (+0.54/−0.38) ka reflects the intensified water–rock interaction due to lower precipitation. Along with prior calcite precipitation effect, this is also observed by increased Mg/Ca and Sr/Ca, while low P, Cu, Be, Y, and Zr concentrations indicate a lowered amount of soil-derived colloidal material. The MIS 5e/5d transition is marked by reduced insolation and enriched δ18O at 116.24 (+0.53/−0.86) ka. The Greenland Interstadial 25 phase at 115.87 (+0.83/−1.71) ka is represented by more negative δ18O and δ13C.

We present the ‘SISAL webApp’—a web-based tool to query the Speleothem Isotope Synthesis and AnaLysis (SISAL) database. The software provides an easy-to-use front-end interface to mine data from the SISAL database while providing the SQL code alongside as a learning tool. It allows for simple and increasingly complex querying of the SISAL database based on various data and metadata fields. The SISAL webApp version currently hosts SISALv2 of the database with 691 records from 294 sites, 512 of which have standardized chronologies. The SISAL webApp has sufficient flexibility to host future versions of the SISAL database, which may include allied speleothem information such as trace elements and cave-monitoring records. The SISAL webApp will increase accessibility to the SISAL database while also functioning as a learning tool for more advanced ways of querying paleoclimate databases. The SISAL webApp is available at http://geochem.hu/SISAL_webApp.

Lamalunga Cave (Altamura, Southern Italy) is renowned for the discovery in 1993 of an excellently preserved Neanderthal skeleton. Given the importance of the findings and the potential use of Lamalunga speleothems for paleoclimate reconstructions, a detailed monitoring program was undertaken to investigate the connections between microclimate parameters and speleothem growth. The cave air temperature is characterized by annual sinusoidal cycles with increasing phase shift and decreasing thermal amplitude from ± 2.1°C to ± 0.04°C as a function of increasing rock overburden, and daily to sub-daily cycles induced by surface air pressure (SAP) variations characterized by strong 24-hour and 12-hour solar harmonic frequencies, with thermal amplitude decreasing from 0.0054°C to 0.0021°C in the deeper parts of the cave. The ventilation regime is mainly controlled by SAP fluctuations. Fast SAP rises can trigger “emptying events” during which most of the cave air is replaced and the CO2 concentration falls towards near-atmospheric values. The steady and gentle ventilation created by SAP fluctuations also influences the growth and morphology of calcite coralloids, with larger popcorn assemblages concentrated in the northern galleries and delicate branching morphologies prevailing along the South Gallery where stable temperature and relative humidity conditions occur. The study is a seminal example of how high-precision measurements of cave air temperature can provide a wealth of information on cave ventilation and thermal regime and provide valuable support for robust paleoclimate reconstruction from speleothems.

Recent research has shown the potential of speleothem δ13C to record a range of environmental processes. Here, we report on 230Th-dated stalagmite δ13C records for southwest Sulawesi, Indonesia, over the last 40,000 yr to investigate the relationship between tropical vegetation productivity and atmospheric methane concentrations. We demonstrate that the Sulawesi stalagmite δ13C record is driven by changes in vegetation productivity and soil respiration and explore the link between soil respiration and tropical methane emissions using HadCM3 and the Sheffield Dynamic Global Vegetation Model. The model indicates that changes in soil respiration are primarily driven by changes in temperature and CO2, in line with our interpretation of stalagmite δ13C. In turn, modelled methane emissions are driven by soil respiration, providing a mechanism that links methane to stalagmite δ13C. This relationship is particularly strong during the last glaciation, indicating a key role for the tropics in controlling atmospheric methane when emissions from high-latitude boreal wetlands were suppressed. With further investigation, the link between δ13C in stalagmites and tropical methane could provide a low-latitude proxy complementary to polar ice core records to improve our understanding of the glacial–interglacial methane budget.

New stalagmites from Qadisha Cave (Lebanon) located at 1720 m above sea level provide a high-resolution and well-dated record for northern Mount Lebanon. The stalagmites grew discontinuously from 9.2 to 5.7 and at 3.5 ka, and they show a tendency to move from a more negative oxygen isotope signal at ~9.1 ka to a more positive signal at ~5.8 ka. Such a trend reflects a change from a wetter to a drier climate at high altitudes. The δ13C signal shows rapid shifts throughout the record and a decreasing trend toward more negative values in the mid-Holocene, suggesting enhanced soil activity. In the short-term trend, Qadisha stalagmites record rapid dry/wet changes on centennial scales, with a tendency to more rapid dry events toward the mid-Holocene. Such changes are characterized by overall good agreement between both geochemical proxies and stalagmite growth and might be affected by the seasonal variations in snow cover. The Qadisha record is in good agreement with other Levantine records, showing more humid conditions from 9 to 7 ka. After 7 ka, a drier climate seems to affect sites at both low- and high-altitude areas. The Qadisha record reflects uniquely mountainous climate characteristics compared with other records, specifically the effect of snow cover and its duration regulating the effective infiltration.