Isotopic lapse rates (ILRs) are important parameters for investigating the elevation of groundwater recharge in mountainous regions, past changes in the elevation of mountain chains, and the determination of paleotemperatures. However, past ILRs remain poorly constrained and proxies providing direct and precisely dated information on the isotopic composition of paleoprecipitation are scarce. Such information can be obtained from fluid inclusions in speleothems, as they contain ancient cave drip waters originating from paleoprecipitation. To fully exploit this potential, it is essential to initially examine ILRs in modern cave drip waters. Through the analysis of the oxygen (δ18Odw) and hydrogen (δ2Hdw) isotopic compositions of 358 cave drip waters from the Swiss Alps and Jura Mountains, collected between 2023 and 2025, we calculated modern ILRs of −0.21 ± 0.02 ‰/100 m for δ18Odw and −1.64 ± 0.12 ‰/100 m for δ2Hdw. These slopes are shallower than 32-year ILRs of regional precipitation and in agreement within uncertainties on multi-annual timescales. 2022 marked the warmest year in Switzerland since instrumental recording started and shows a strong enrichment of stable isotopes in precipitation, which resulted in enriched cave drip waters in the following years. This demonstrates the close connection between cave drip waters and regional precipitation. Furthermore, the preliminary hydrogen paleo-ILR of −2.06 ± 0.18 ‰/100 m, based on late-to mid-Holocene and last interglacial speleothem fluid inclusions, agrees with the hydrogen ILR in modern precipitation. Overall, this study demonstrates the potential of speleothem fluid inclusions to investigate paleo-ILRs.

A major challenge in the interdisciplinary study of past climates is ensuring that evidence and data relating to different disciplines are analysed effectively using appropriate methodologies. In ‘Droughts and conflict during the late Roman period’, Clim. Chang 178, 2025, Norman et al. argue that historical sources support their conclusions that drought contributed causally to the ‘barbarian conspiracy’ of 367CE and to other late Roman conflicts. Although historians have developed rigorous methodologies for effective analysis and interpretation of surviving texts, the authors outline no methodologies for dealing with the textual evidence. Further, there are issues with the historical ‘conflict’ and numismatic datasets and with their interpretation. We focus on four major evidential points: 1) the ‘barbarian conspiracy’, 2) the agricultural economy; 3) the ‘conflict’ dataset and 4) the coin dataset. Historical evidence relating to drought and famine in the late Roman Empire does exist: future interdisciplinary research may indeed offer interesting observations on the relationships between drought and conflict, but the textual evidence discussed by Norman et al. does not, and cannot, support the authors’ assertions. Effective interdisciplinary research must allow all disciplines to engage on their own terms and with their own accepted standards of rigour.

The Sasanian Empire (224–651 CE) has been given relatively little attention in research on climate-society interactions when compared to the neighboring Byzantine Empire, despite evidence of changing conditions and an agricultural economy that is theoretically vulnerable to droughts due to low annual precipitation. We review the available historical, archaeological, paleo-environmental, and paleo-climatic evidence to assess whether climatic conditions factored into periods of Sasanian growth and decline. We find evidence for drier conditions across Sasanian territories at the turn of the sixth century, a pattern that extends to the Aegean, Anatolia, and Central Asia. These same conditions contributed to a significant decline for the nearby Kingdom of Himyar but occurred alongside a period of expansion and intensification for the Sasanian Empire. We suggest that a combination of careful management of water infrastructure, including qanats, which can conserve water resources during dry periods, and land-use strategies that are both diverse and flexible, may have mitigated the worst impacts of this dry period. However, we note several weaknesses in the available data that still hinder confident interpretations of the potential impacts of climate change in the Sasanian Empire. Notably, there are gaps in the coverage of paleo-hydrological records and a complete lack of terrestrial paleo-temperature records in the region, as well as low resolution and high chronological uncertainties in the archaeological and paleo-environmental evidence.

NW Türkiye is uniquely positioned between climatic influences from the North Atlantic, Mediterranean and Eurasia. Variability in climate systems through the Late Holocene is thought to have influenced major historical transitions, such as the ‘Bronze Age Collapse’, and during periods including the ‘Roman Climate Anomaly’ and the ‘Little Ice Age’. The region is noteworthy considering its geographical and historical significance over the last 4,000 years as a landscape for Ancient Greece Colonisation, the Roman Byzantine and Ottoman Empires and proximity to the common focal-point of modern-day Istanbul (Byzantium, Constantinople) which received much of its water from the cave’s locality. With the Eastern Mediterranean a hotspot for agricultural drought (Dabanlı et. al; 2017), which has impacted societies historically, the region warrants the study of spatio-temporal human-climate interactions.Given the scarcity of sub-decadal palaeoclimate records regionally, and heterogeneity of Eastern Mediterranean climate generally (Jacobson et. al; 2021), stalagmite U-1 from Uzuntarla cave in Thrace helps fill this gap. Speleothem U-1 was dated using a combination of U/Th and 14C dates. The chronology is further refined by aligning distinct growth-shifts with well-dated and strong historical earthquakes. Using the combined evidence of calcite fabric and growth laminae changes, stable isotope (δ13C, δ18O), trace elements (Mg/Ca, Sr/Ca, P/Ca) and fluid-inclusion analysis, we find that U-1 is highly sensitive to changes in cold-season regional precipitation, seasonality and temperature. For example, increases in δ13C often coincide with narrowing of growth-laminae and increased Sr/Ca suggesting a unified influence by reduced drip-rate during poor recharge conditions. Effective infiltration is between Oct:Mar, making δ18O a combined indicator for Fall:Winter:Spring seasonality balance and temperature. Initial fluid inclusion temperature estimates are promising with work ongoing, however other factors are worth discussing such as aeolian oceanic Mg inputs. Initial results, often complimenting other regional palaeoclimate records, paints a picture of dynamic changes in climate over the last 3,900 years BP spanning key historical transitions. Speleothem U-1 describes a large shift in aquifer-recharge and seasonality preceding the Bronze Age Collapse impacting SW Asia around 1190 BCE. Recharge then peaks anomalously in 650-690 BCE during the Homeric Minimum, coinciding with the Greek Colonisation and Byzantium’s founding ~667 BCE. The acclaimed Roman Climate Anomaly (150 BCE-200 CE) is without wet-anomalies but stable for U-1, with later evidence of aridification. Wetter and stable conditions follow during 200-600 CE, a period encompassing defining historical events including the establishment of Constantinople as a powerhouse of the East Roman Empire and major infrastructure development including aqueduct expansion into Thrace. The Medieval Climate Anomaly (950-1250 CE) is defined by wet conditions during 760-1100 CE transitioning into lower aquifer recharge between 1100-1220 CE. Finally, the Little Ice Age (1400-1700 CE) shows highly variable conditions, but generally transitions from a wetter and colder period to lower aquifer recharge between 1220 and 1760 CE. REFERENCESDabanlı et. al; 2017. Long-term spatio-temporal drought variability in Turkey. Journal of Hydrology, 552, pp.779-792.Jacobson et. al; 2021. Heterogenous late Holocene climate in the Eastern Mediterranean—the Kocain Cave record from SW Turkey. Geophysical Research Letters, 48(20), p.e2021GL094733.

The Eastern Mediterranean including the Black Sea region is influenced by subtropical Mediterranean, temperate European, and continental Asian air masses which make paleoclimate archives from the Black Sea region a valuable source of information about past climatic changes in temperature and rainfall. On glacial interglacial time scales, most information on climate variability in the Black Sea region comes almost entirely from marine/lake sediment cores (e.g. Wegwerth et al., 2015, 2020; Shumilovskikh et al., 2012). In contrast to these paleoclimate archives, oxygen isotope ratios of speleothem calcite (δ18O) and water isotope ratios (δDFI and δ18OFI) of speleothem fluid inclusions from Sofular Cave in northern Turkey can provide direct information on the isotopic composition of rainfall and, therefore, potentially identify the sources of moisture at the Black Sea coast. During the last 650’000 years most of the δDFI and δ18OFI values plot closer to the Local Meteoric Water Line (LMWL) than to the Eastern Mediterranean Water Line (EMWL). This indicates that the Black Sea was the dominant moisture source for Sofular Cave during glacial and interglacial periods (Fleitmann et al., 2009; Badertscher et al., 2011). In addition, isotope measurements on speleothem fluid inclusions enables us to reconstruct temperature changes. Holocene temperatures of ~15°C to ~20°C are within the range of modern cave air temperatures and proxy records from the Black Sea (Sanchi et al., 2014; Ménot and Bard, 2012). During the last glacial period fluid inclusions indicate a temperature increase associated with Dansgaard-Oeschger warming events. REFERENCES Badertscher, S., Fleitmann, D., Cheng, H., Edwards, R.L., Göktürk, O.M., Zumbühl, A., Leuenberger, M., Tüysüz, O. 2011: Pleistocene water intrusions from the mediterranean and caspian seas into the Black Sea, Nature Geoscience, 4 (4), 236–239. Fleitmann, D., Cheng, H., Badertscher, S., Edwards, R.L., Mudelsee, M., Goktürk, O.M., Fankhauser, A., Pickering, R., Raible, C.C., Matter, A., Kramers, J., Tüysüz, O. 2009: Timing and climatic impact of Greenland interstadials recorded in stalagmites from northern Turkey, Geophysical Research Letters, 36 (19), L19707. Menot, G., & Bard, E. 2012: A precise search for drastic temperature shifts of the past 40,000 years in southeastern Europe, Paleoceanography, 27(2). Sanchi, L., Ménot, G., & Bard, E. 2014: Insights into continental temperatures in the northwestern Black Sea area during the Last Glacial period using branched tetraether lipids, Quaternary Science Reviews, 84, 98-108. Shumilovskikh, L. S., Tarasov, P., Arz, H. W., Fleitmann, D., Marret, F., Nowaczyk, N., Plessen, B., Schlütz, F. & Behling, H. 2012: Vegetation and environmental dynamics in the southern Black Sea region since 18 kyr BP derived from the marine core 22-GC3, Palaeogeography, Palaeoclimatology, Palaeoecology, 337, 177-193. Wegwerth, A., Ganopolski, A., Ménot, G., Kaiser, J., Dellwig, O., Bard, E., Lamy, F. & Arz, H. W. 2015: Black Sea temperature response to glacial millennial‐scale climate variability, Geophysical Research Letters, 42(19), 8147-8154. Wegwerth, A., Kaiser, J., Dellwig, O., & Arz, H. W. 2020: Impact of Eurasian ice sheet and North Atlantic climate dynamics on Black Sea temperature variability during the penultimate glacial (MIS 6, 130–184 ka BP), Paleoceanography and Paleoclimatology, 35(8), e2020PA003882.

Understanding how climate change manifests across the Mediterranean basin is critical for predicting the impacts of future climate change. The Black Sea region (BSR) is one of the most vulnerable areas of the Mediterranean climate change hotspot, owing to its high sensitivity to both local and global-scale climate feedbacks1. However, few paleoclimate records exist with sufficient resolution, and length, to fully assess significance of these feedbacks on timescales exceeding the window of instrumental observation2. Here, we present a ~230-year-long, seasonally-resolved stable isotope record record of effective moisture and temperature variability from stalagmite So-11, which grew in Sofular Cave (Northern Türkiye) between 1779 and 2008 CE. The sample contains 229 continuous, well-developed laminae couplets with a mean wavelength of ~0.95 mm a-1, suggesting that each dark-to-light couplet corresponds to one calendar year. This assumption is supported by two U-Th ages, which show good agreement with the layer-counted chronology generated using the date of collection (2008 CE) as an upper anchor point. Minima in δ13C closely track the dense, dark, compact calcite layers, and are typically followed by a distinct δ13C peak in conjunction with formation of white, porous calcite layers. We interpret these oscillations as seasonal changes in effective moisture, with the lowest δ13C values corresponding to high drip rates, lower CO2 degassing, and weaker fractionation during winter months – reflecting the high responsivity of the Sofular Cave system to transient changes in local precipitation3,4. Marked changes in the geochemistry of So-11 also coincide with the Little Ice Age (1850 to 1870 CE), and the progressive increase in global atmospheric CO2 in response to increased fossil fuel combustion during the 20th and 21st centuries5. Our results underscore how high-resolution, speleothem-based paleoclimate reconstructions can provide important context not only for constraint of global circulation model (GCM) simulations, but also closer examination of human-climate-environment interactions during the Late Holocene. ~~1Giorgi, F. (2006) Geophysical Research Letters 33(8): L087072Burstyn, Y. et al. (2019) Quaternary 2:163Göktürk et al. (2011) Quaternary Science Reviews 30: 2433-24454Rudzka, D. et al. (2011) Geochimica et. Cosmochimica Acta 75 : 4321–43395Bauska, T. K. et al. (2015) Nature Geoscience 8: 383–387

Worldwide, fault zones in carbonates regularly host medium to large earthquakes including recent ones in the Mediterranean and Middle East. In addition to that, faults can control fluid flow by either acting as a conduit or seal for fluid pathways and should be considered in e.g., geothermal exploration. Hence, understanding the (micro-) structural evolution of these fault zones as well as fluid mediated geochemical processes involved in their dynamic deformation history allows to better address topics of societal and economic relevance ranging from seismic hazards to the exploitation of natural resources. Unfortunately, active in-situ deformation at depth is difficult to access, emphasising the need for investigations on suitable exhumed analogues.This study focuses on the microstructural and geochemical record of a recently exposed seismogenic dextral strike-slip fault zone in the seismically active southwestern Swiss Alps. Due to excellent outcrop conditions on glacially polished rock surfaces and a wide range of preserved tectonites and associated deformation structures, this particular fault zone provides a valuable record of potential paleoseismicity in carbonates. We combined microstructural analyses with micro-chemical and isotope data in order to reconstruct the spatio-temporal evolution of high-strain domains at variable crustal levels throughout exhumation. While the microstructural record allows us to differentiate between rate-dependent brittle and viscous deformation phases, we use the geochemical fingerprint to distinguish and characterize individual fluid pulses.Here, we present microstructural evidence of fast, possibly seismic, deformation along a principal slip zone. While injection structures containing fluidized material, suggest highest deformation rates as feasible for seismic events, repeated brittle deformation that was accompanied by the formation of cataclasites and calcite veins, hints towards fast seismic to sub-seismic rates.We also found that newly formed calcite crystals, in veins and linkage zones, show significantly decreasing δ18OSMOWvalues, as low as 5 ‰ δ18OSMOW, implying an influence of meteoric water. Clumped isotope thermometry of such calcites resulted in temperatures of 65-95°C, which are approximately 100°C lower than Tmax in the area. This suggests that the analyzed material did not record any potential shear heating. Moreover, the investigated tectonites have most likely formed along a retrograde exhumation path. In combination with detailed observations on the m- to 10er-m-scale our observations provide a dataset that allows direct comparison of different deformation processes and correlation of paleo-seismicity to fluid flow in fault zones. Further, we contribute to the longstanding discussion of differentiating microstructural evidence for seismic slip from slow or aseismic slip in carbonate hosted fault zones.

Hydrogen (δD) and oxygen (δ18O) stable isotopes contained in speleothem (cave carbonate) fluid inclusion water allow the quantitative reconstruction of past temperatures. Reconstructions can be based either on the use of a regional modern transfer function between isotopes in precipitation and temperatures (expressed in ‰ / °C) or based on the fractionation between the oxygen isotopes measured in the calcium carbonate and in the corresponding inclusion water. One advantage of this proxy is that temperature reconstruction is constrained by chemico-physical processes. Based on a δD gradient of 3.84‰ / 1°C, we reconstructed quantitative temperature variations occurring during the interval 9.0 ka to 7.8 ka BP for the central and western Europe area with a mean temporal resolution of approximately 25 years. The isotope profile shows that the 8.2 ka cold event is characterized by negative shifts in δD and δ18O consistent with numerous records from across the Northern Hemisphere such as for example Mondsee and Ammersee lake sediments in central Europe or at a larger scale in ice cores from Greenland. Across the 8.2 ka event, the new high-resolution Milandre Cave Fluid Inclusion Temperature (MC-FIT) shows a remarkable similarity with the physically constrained temperature reconstruction from Greenland ice cores that is based on nitrogen and argon isotopes of trapped air (Kobashi et al., 2017). This record, supported by additional speleothems from a neighboring cave, provides a better understanding of the continental temperature evolution across the 8.2 ka event.Affolter S. et al.: Central Europe temperature constrained by speleothem fluid inclusion water isotopes over the past 14,000 years. Sci. Adv.5, eaav3809. DOI:10.1126/sciadv.aav3809, 2019Kobashi, T., Menviel, L., Jeltsch-Thömmes, A. et al.: Volcanic influence on centennial to millennial Holocene Greenland temperature change. Sci Rep 7, 1441. https://doi.org/10.1038/s41598-017-01451-7, 2017

Changes in the hydrological balance of the Black Sea play a crucial role in the hydrological cycle and exert a strong influence on the isotopic composition of precipitation in the Black Sea region. However, the timing, duration and driving factors of hydrological shifts in the Black Sea region remain poorly constrained. Here, we present several new speleothem records from Sofular Cave in northern T & uuml;rkiye to reconstruct hydroclimate fluctuations during the last 670,000 years, thereby expanding the previously published discontinuous isotope records. Stable oxygen isotopes of speleothem calcite (618Oca) reflect variations in the isotopic composition of the Black Sea surface water, providing information on the timing, origin and duration of Black Sea water exchange with the Mediterranean and Caspian Seas, inflow of meltwater from the Eurasian ice sheet (EIS), and configuration of the Black Sea paleodrainage basin and EIS during the last 670,000 years. The comparison between stable water isotopes of modern precipitation and paleo-precipitation trapped inside speleothem fluid inclusions demonstrates that the modern Local Meteoric Water Line (LMWL) is representative for the isotopic composition of precipitation during glacial and interglacial climate conditions. Furthermore, speleothem fluid inclusion deuterium excess values were higher during glacial periods compared to interglacial periods, which is most likely related to atmospheric changes affecting the evaporative conditions above the moisture source.

Understanding past hydroclimate dynamics of the Eastern Mediterranean is crucial for predicting future climate impacts. However, the 'Marmara Transition Zone' in northwest Turkiye, a region of significant societal transformation, lacks high-resolution pre-industrial climate records. Continuous paleoclimate reconstructions are critical to reveal the nature and pattern of Late Holocene hydroclimatic changes and extremes, and to study their impacts on societies. Here, we present a precisely dated and sub-decadal resolution speleothem record from Uzuntarla cave, located near to Istanbul (historically Byzantium and Constantinople), that shows sensitivity to cold-season rainfall amount and seasonality for the Late Holocene. Prior to 2005 CE, stalagmite U-1 reveals two periods of high multidecadal variability of cold-seasonal rainfall in similar to 1900-400 BCE and similar to 690-1900 CE, separated by a relatively stable phase. This variability aligns with the rise and fall of Byzantine agrarian productivity between similar to 350 and 1250 CE, while the most pronounced aridification anomaly in similar to 1210-1170 BCE coincides with the collapse of the Hittite Empire (c. similar to 1200 BCE), partly linked to regional famine and drought. Our findings indicate that the transition from the Late Bronze Age to the Iron Age in the Marmara Transition Zone was marked by a pronounced shift in the regional climate regime. Namely, that a previously warmer and more stable 'Mediterranean-style' climate shifted toward cooler conditions characterised by increased rainfall variability, and a greater influence of moisture sourced from the Black Sea. Therefore, we suggest that cold-seasonal rains played a critical role in shaping human-climate interactions, power dynamics, and social stability in the Eastern Mediterranean during the Late Holocene. This record offers valuable context for understanding how hydroclimate variability influenced past societies, highlighting the importance of climate as a driver in historical societal resilience and collapse.

While the modern stable isotope lapse rate for precipitation shows a gradient of -0.19 ‰ per 100 meters elevation for Switzerland (Schotterer, 2010), there is only scarce information about the isotope lapse rate in the past and it is usually assumed that they remained constant through time. To investigate the lapse rate in the past, we use speleothems from caves along an altitudinal transect, which contain past drip water 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, allowing us to determine lapse rates in the past. To extract and analyze this water, we used an improved speleothem fluid inclusion water extraction line available at the Quaternary Geology group of the University of Basel. The new design allows us to measure up to ten samples a day. For this study, we measured more than 100 fluid inclusion samples from various stalagmites in a transect from the Jura mountains to the swiss alps with elevations ranging between 373 and 2’000 meters. These measurements enable us to obtain direct information on past precipitation as well as determine absolute paleotemperatures (Affolter et al., 2019). They allow us to determine the stable isotope and temperature lapse rates for different time intervals, such as Marine isotope stage 5a, the Younger Dryas and the Holocene. Furthermore, to better understand the water isotopes in cave environments, we have launched (in 2023) the Citizen Science project “Cave Drip Water” in collaboration with various caving clubs in Switzerland and France (https://duw.unibas.ch/de/quartaergeologie/citizen-science/). The purpose of this program is to collect drip water samples and consequently monitor stable isotopes from numerous caves distributed at different elevations across Switzerland and in neighbouring regions. From this data, we will reconstruct a modern cave drip water lapse rate for Switzerland. In addition, it will allow us to investigate the spatial distribution of water isotopes in karst systems and compare it with the most recent water isotope patterns in precipitation from Switzerland. Moreover, these observations will set a baseline for the use of water isotopes analyzed in speleothem fluid inclusion measurements. Here we present preliminary isotope and temperature lapse rates based on speleothem fluid inclusion water for the Holocene, Younger Dryas and the MIS 5a intervals as well as the first results from the Citizen science project “Cave Drip Water”. REFERENCES Schotterer U., Schürch M., Rickli R., Stichler W. (2010). “Wasserisotope in der Schweiz: Neue Ergebnisse und Erfahrungen aus dem nationalen Messnetz ISOT“ Gas, Wasser, Abwasser 2010 Affolter et al. (2019), Sci. Adv. 5 eaav3809, doi.org/10.1126/sciadv.aav3809

In Mesopotamia, climate is regarded as an important contributing factor to major socio-cultural transformations. However, the scarcity of Holocene paleoclimate reconstructions in this region impedes analysis of potential climate-human interactions. Furthermore, current hydroclimatic scenarios for Mesopotamia are predominantly based on oxygen isotope (518O) proxy records from the eastern Mediterranean, whereas the paleoclimatic significance of 518O remains debated. Here, we present a Holocene stalagmite multi-proxy record from Shalaii Cave in northern Mesopotamia. Based on stable isotope, trace element and strontium isotope measurements, our new Shalaii Cave record suggests that long-term changes in 518O were influenced by multiple factors, such as 518O changes of the source of moisture, amount and seasonality of rainfall. The Shalaii Cave trace element and strontium isotope records indicate rather dry conditions during the early Holocene and wettest conditions during the mid-Holocene. This mid-Holocene hydroclimate optimum at Shalaii Cave is in good agreement with other non-isotopic records from SW-Asia, such as pollen evidence for concurrent rapid forest expansion and peaking lake levels. The mid-Holocene hydroclimatic optimum is most likely related to an increase in the amount of spring precipitation related to the remote influence of the Indian summer monsoon (desert-monsoon mechanism) and spring insolation-driven weakening of the Arabian anticyclone. In particular the latter northward migration of the Arabian anticyclone in spring promoted a longer spring rainfall season.

The study of glacial to interglacial climate transitions is extremely important for understanding the full scale of climate variability from global to local scale. Unfortunately, there are large areas where multimillennial paleoclimate timeseries are unavailable. Southern Caucasus, is such a region as currently only a few continental climate time series extend beyond the short instrumental records. Importantly, temperature-related proxies are virtually absent here, thus impeding to evaluate how global-scale rapid climate instabilities propagate and impact this area. This work provides the first paleoclimate reconstruction from Georgia (Southern Caucasus) spanning approximately the last 13500 years. Four stalagmites named Zak-1, Zak-3, Zak-4 and Zak-6, measuring 46, 50, 55 and 102 cm respectively, were collected from the Zakariasklde Cave (42°10′ N; 43°20′ E). Dated by the U-Th method, Zak-1 was deposited between 3.1+0.04/-0.03 to 0.32+0.46/-0.44 ka (ka = kiloyears before 1950 AD); Zak-3 between 13.48+0.07/-0.08 to 10.11+0.05/-0.09 ka; Zak-4 between 12.01+0.08/-0.09 to 9.73+0.53/-0.61 ka; and Zak-6 between 8.77+0.07/-0.08 to 0.71+0.16/-0.13 ka, with a possible hiatus between 4.45+0.19/-1.49 and 3.27+1.35/- 0.34 ka. Timeseries of δ18O-δ13C from calcite show the main patterns of temperature variations during the last glacial-interglacial shift as well as throughout the Holocene, which mostly agree in pace and tempo with global records (i.e., Greenland ice and Atlantic/Mediterranean sediment cores). Then, δ18O-δ2H from speleothem fluid inclusions (FI) are preliminarily applied to quantitatively calculate temperatures. Conveniently, FI resulted well aligned with the modern meteoric water line in Georgia, thus indicating that isotopic fractionation occurred during the karst flow-path and calcite precipitation was negligible. FI-derived temperatures document the effects of climate warming in Southern Caucasus related to the last deglaciation, with a ca. 4.5ºC increase of average temperatures from ~12 to ~10 ka. Paleotemperatures during the Holocene instead presents a gradual decrease of around 2ºC from ~10 ka to ~3 ka. This potentially supports the existence of a Holocene thermal maximum during the Early Holocene, which is still a matter of debate. However, calculation uncertainties make this finding debatable. The interpretation of the record is refined by considering changes of rainfall (e.g., amount, provenance/source and seasonality) as well as soils (e.g., vegetation bioactivity). To comprehend the climate mechanisms of South Caucasus climate during rapid global instabilities, the Zak-timeseries is compared to the others from different climate regimes to advance the current characterization of regional climate shifts. Therefore, the results of this study certainly help to further investigate possible climatic teleconnections on a regional to global scale.

The Saharo-Arabian Desert is one of the largest biogeographical barriers on Earth, impeding dispersals between Africa and Eurasia, including movements of past hominins. Recent research suggests that this barrier has been in place since at least 11 million years ago 1 . In contrast, fossil evidence from the late Miocene epoch and the Pleistocene epoch suggests the episodic presence within the Saharo-Arabian Desert interior of water-dependent fauna (for example, crocodiles, equids, hippopotamids and proboscideans) 2–6 , sustained by rivers and lakes 7,8 that are largely absent from today’s arid landscape. Although numerous humid phases occurred in southern Arabia during the past 1.1 million years 9 , little is known about Arabia’s palaeoclimate before this time. Here, based on a climatic record from desert speleothems, we show recurrent humid intervals in the central Arabian interior over the past 8 million years. Precipitation during humid intervals decreased and became more variable over time, as the monsoon’s influence weakened, coinciding with enhanced Northern Hemisphere polar ice cover during the Pleistocene. Wetter conditions likely facilitated mammalian dispersals between Africa and Eurasia, with Arabia acting as a key crossroads for continental-scale biogeographic exchanges.

The link between geomagnetic excursions and climate is an exciting but still unresolved topic. The idea reposes on the increased solar and cosmic ray radiation in response to the weakened magnetic field during the transitional fields accompanying a geomagnetic reversal or excursion. However, a direct climate response to the variations of the Earth magnetic field is not yet demonstrated in the geological record. A major limitation resides in the fact that paleomagnetic data are usually extracted from igneous or sedimentary rocks, which usually provide no or poor-quality paleoclimate information. Recent advances in speleothem magnetism fill this gap and open a new door to investigate the link between climate and the variation of the Earth magnetic field in the same geological archive. Here we document absolute paleotemperatures based on water isotopes in fluid inclusions from a Portuguese stalagmite that recorded the Laschamps geomagnetic excursion (~42 kyrs). The stalagmite was dated by radiocarbon method. Paleomagnetic data show the complete record of the Laschamps geomagnetic excursion, with paleomagnetic poles moving from the north pole down to the south pole and returning to the original position in ~3000 kyrs. Paleointensity data show a weakened magnetic field associated with the migration of the paleomagnetic pole. Absolute paleotemperatures were calculated using the fluid inclusion hydrogen isotope (d2H) and the calcite-water isotope fractionation paleothermometer on 19 samples encompassing the Laschamps event. The data show increased absolute temperatures just before and during the Laschamps. However, a strong correlation is noted between the absolute temperature calculated here and the oxygen isotope composition of the NGRIP ice core. Although the relation between paleotemperatures and the Laschamps event is not yet fully demonstrated in this case, the combination of paleomagnetic techniques coupled to isotope composition in speleothems offers new and promising perspectives to investigate the relationship between climate and the Earth magnetic field. This project is funded by Portuguese Fundação para a Ciência e Tecnologia, FCT, I.P./MCTES through national funds (PIDDAC): UID/50019/2025, UIDB/50019/2020 (https://doi.org/10.54499/UIDB/50019/2020), LA/P/0068/2020 (https://doi.org/10.54499/LA/P/0068/2020), and PTDC/CTA-GEO/0125/2021.

Climate change is thought to have played a significant role in the rise and demise of complex Mesopotamian societies throughout the mid-to late Holocene. However, assessing the links between societal change and climate variability has been historically challenging, in part due to an absence of long-term, well-dated palaeoclimate archives located in close proximity to key archaeological sites. Here, we synthesise proxy data with archaeological information from Mesopotamia to demonstrate that the earliest urban development documented in this region coincides with increasing and potentially peak effective moisture in the mid-Holocene by similar to 5500 BP. We posit that increasing moisture availability likely facilitated the expansion and development of the earliest cities, with resource extraction under favourable climatic conditions providing new opportunities for urban centres to expand their resource areas into new domains, and far beyond what is evident in earlier periods. Following similar to 5200 BP, these same archives show increasing aridity coincident with the end of the Late Chalcolithic, and abandonment of several key settlements. Taken together, our work contextualises the evolution of critical urban centres in Mesopotamia between 6500 to 5500 yrs BP, and underscores the sensitivity of these centres to climatological variability.

Speleothems are continental archive used to reconstruct paleoclimate and paleoenvironmental settings at a high resolution of time. One advantage is that they can be precisely dated using Uranium-Thorium dating methods. Speleothems usually contain small amounts of paleowater trapped in micrometer voids named fluid inclusions, which are sealed in the calcite fabric. This water constitutes a witness of past precipitation falling above the cave at the time the inclusion was sealed. To extract and analyze this water, we use a crushing and extraction line available at the Quaternary Geology group of the University of Basel, that allows the simultaneous analyses of fluid inclusion oxygen (δ18Ofi) and hydrogen (δDfi) water isotopes. In this study, we analyzed several stalagmites from Milandre Cave (Jura Mountains, Switzerland). Previous studies from this cave have already shown that δ18Ofi and δDfi can serve as key-proxies for paleotemperature reconstruction in central Europe (Affolter et al., 2019). For the temperature reconstruction, we use either the oxygen isotope fractionation between calcite and water as a paleothermometer or a transfer function based on the regional modern relationship between the water isotopes in precipitation and temperature. The resulting temperature estimates provide absolute mean annual cave and surface air temperatures, which, however, may be slightly biased towards the cold season. Stalagmites investigated in this study cover several glacial and interglacial periods, allowing us to reconstruct temperatures for the Holocene, Younger Dryas as well as for Marine Isotope Stages 5, 7, 8 and 9. Our preliminary results show absolute mean annual temperature in a plausible range with values ranging between 0°C and 9.6°C. To gain more information about glacial temperature change, we will use stalagmites coming from additional caves located in the western part of the Jura Mountains.These quantitative paleotemperature snapshots obtained from Milandre Cave, together with those obtained from speleothems from neighboring caves in the Jura Mountains, will allow to document and enhance the comprehension of the temperature evolution of central Europe over the last 300,000 years before present. Affolter et al. (2019), Sci. Adv. 5 eaav3809, doi.org/10.1126/sciadv.aav3809

With the efflorescence of palaeoscientific approaches to the past, historians have been confronted with a wealth of new evidence on both human and natural phenomena, from human disease and migration to landscape change and climate. These new data require a rewriting of our narratives of the past, questioning what constitutes an authoritative historical source and who is entitled to recount history to contemporary societies. Humanities-based historical inquiry must embrace this new evidence, but to do so historians need to engage with it critically, just as they do with textual and material sources. This article highlights the most vital methodological issues, ranging from the spatiotemporal scales and heterogeneity of the new evidence to the new roles attributed to quantitative methods and the place of scientific data in narrative construction. It considers areas of study where the palaeosciences have “intruded” into fields and subjects previously reserved for historians, especially socioeconomic, climate, and environmental history. The authors argue that active engagement with new approaches is urgently needed if historians want to contribute to our evolving understanding of the challenges of the Anthropocene.

Speleothems (cave carbonate) contain fluid inclusions that are natural repositories of cave drip water and precipitation respectively. This water is stored within the speleothem calcite matrix and well preserved from post-depositional alterations in cave environments. Extracting the water and analysing its isotopes provide direct information about the hydrological cycle on timescales ranging from months (<1 year), to millions of years (>106 years). Therefore, speleothem fluid inclusions offer the opportunity to address key questions about paleorainfall and paleotemperatures, as water isotopes can be used to reconstruct temperatures or origin of moisture at the time of calcite deposition. This review aims to explore the background and history of speleothem fluid inclusion science and the development of analytical methods and records, thereby giving new insights into the potential of fluid inclusions. Based on a compilation of available speleothem fluid inclusion water isotopes, we developed a paleo-Global Meteoric Water Line (paleo-GMWL) that shows a similar slope to modern precipitation which corroborates the potential of fluid inclusions in the reconstruction of past precipitation. Similarly, first spatial observations seem to highlight the potential of fluid inclusions to contribute to a Global Network of Isotopes in Precipitation in the past (paleo-GNIP). Recent analytical developments will further enable the production of highly-resolved water isotope records for continental areas. Therefore, overall, there is a great potential in the use of speleothem fluid inclusions in paleoclimate sciences, which will provide information about past climate and allow data-model comparisons.

The last glacial period is characterized by abrupt climate oscillations, also known as Dansgaard-Oeschger (D-O) cycles. However, D-O cycles remain poorly documented in climate proxy records covering the penultimate glacial period. Here we present highly resolved and precisely dated speleothem time series from Sofular Cave in northern Türkiye to provide clear evidence for D-O cycles during Marine Isotope Stage (MIS) 6 as well as MIS 2-4. D-O cycles are most clearly expressed in the Sofular carbon isotope time series, which correlate inversely with regional sea surface temperature (SST) records from the Black Sea. The pacing of D-O cycles is almost twice as long during MIS 6 compared to MIS 2-4, and could be related to a weaker Atlantic Meridional Overturning Circulation (AMOC) and a different mean climate during MIS 6 compared to MIS 2-4, leading most likely to a higher threshold for the occurrence of D-O cycles.