The glaciokarst of the Yorkshire Dales National Park, situated in the English Pennine hills, 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 which has been reappraised over recent decades as being a dynamic and unstable body. The caves were extensively excavated by Victorian (1837-1901) and Edwardian (1901-1910) antiquarians/archaeologists but was then largely ignored until the development of radiometric dating in the late 1970 and early 1980s. Since then scientific and archaeological attention has been sporadic and piecemeal with studies often being driven by the findings of the very active cave exploration community which have been responsible for the discovery of the approximately 90 km long Three Counties System in the west of the area.

The hills and valleys to the east of the area are less visited by both cavers and cave scientists though there is great potential for discovering new caves. A detailed study was undertaken on the complex Stump Cross cave system beneath one of the wide interfluves in the 1980s which has been subject to a recent reappraisal but otherwise scientific attention has been limited and sporadic. In this study a dendritic cave system dissected by the glaciated trough valley of Littondale has been subjected to study by an ad-hoc group of scientists, both citizen and academic, along with a team of cavers and cave divers. The now perched valley side caves reveal a complex record of drainage and flooding presumably related to the reoccupation of the valley by successive ice sheets and the resulting episodic down cutting. Speleothem damage provides the first evidence for the existence of ice bodies within the regions caves. Archaeological findings have shown Roman use of caves in the region is geographically more extensive than previously thought and have provided constraining evidence for the ongoing investigation of an early medieval murder mystery. This study highlights the potential of the area for future detailed paleo climate studies.

The work was supported by funding from the British Cave Research Association Cave Science and Technology Research Initiative.

How to cite: Murphy, P.: Ice, Incision and Execution in the eastern Yorkshire Dales – citizen cave science and climate studies in the karst of northern England., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1461, https://doi.org/10.5194/egusphere-egu23-1461, 2023.

Atmospheric temperature variations are characterized by different frequency-modes including yearly and daily fluctuations as well as yearly average temperatures. In a ventilated cave, the thermal amplitude is attenuated with increasing distance from the upper and/or lower cave entrance. Convective heat flux for dry air is exchanged with cave wall and the heat transferred by conduction to the surrounding rock is attenuated within a certain distance. Here, we aim at determining the thermal attenuation length for the different modes along a cave and the surrounding rock. Distribution of amplitude of fluctuations along the cave is specified by using Fourier series expansion for dominant modes. In next steps, the effect of latent heat exchange at the cave wall due to evaporation or condensation will be studied. The main variables controlling thermal perturbations in ventilated caves are recognized and compared with field data by developing a numerical model based on the heat and mass transfer between the rock and the air. Moreover, our model aims to quantify the air and wall temperature profile along the conduit for a one-year. The model calculates water-vapor exchange rate along the cave showing the amount of consumed or produced water by evaporation or condensation along the cave and provides the rock temperature distribution in the surrounding hostrock. Our preliminary results contribute to a better understanding of the long-term cave dynamics and may support a quantitative interpretation of speleothem records.

How to cite: Sedaghatkish, A., Pastore, C., Jeannin, P.-Y., Luetscher, M., and Doumenc, F.: Numerical Modeling of Heat Transfer and Thermal Attenuation Lengths in Ventilated Caves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2667, https://doi.org/10.5194/egusphere-egu23-2667, 2023.

Speleothems are increasingly widely studied globally, but some regions remain poorly covered, including NW France. The cave-quarry of Caumont, located in Normandy develops in chalk limestone and contains speleothem formations from different time intervals. Chalk was extracted from this quarry for building stone since Roman times well into the 20th century. We collected several stalagmites from one of the excavated chambers with the aim to investigate their sensitivity to environmental signals. Of particular interest is stalagmite CCB-1 which was deposited over the last century and likely holds highly detailed climatic signals. We have tested whether stalagmite CCB-1 records hydrological or thermal seasonality, and if atmospheric circulation patterns can be reconstructed from this sample. To establish modern baselines we monitored temperature, drip rate, drip water isotopes, and collected modern carbonate precipitates between November 2019 and July 2021. The monitoring revealed that in-cave conditions are very stable all year round (T_{cave air}= 10.4 ±0.3°C; δ¹⁸O_drip and δD_drip change is ~0.1‰ and <0.8‰ respectively). Modern calcite samples fall mostly on the Coplen (2007) equilibrium regression line, suggesting that modern precipitation occurs near isotope equilibrium.

From sample CCB-1 we obtained three U/Th dates, counted 114 growth laminae and analysed 750 samples for stable isotope composition. The age model was constrained with laminae counting, historical inscriptions, and grey value based annual growth counting measurements and provides an annually resolved record for the last 114 years (1905 to 2019). The δ¹⁸O and δ¹³C signals from CCB-1 were compared with surface climatic parameters including precipitation, temperature, and the standardised precipitation evapotranspiration index (SPEI) for the last century. While δ¹⁸O of carbonate is influenced by surface temperature and the original isotopic composition in precipitation, the δ¹³C signal is governed by effective moisture supply and prior carbonate precipitation. Our reconstruction analysis reveals a significant change in the isotope record after ca. 1960. This change is best seen when comparing the δ¹³C time series with the SPEI and might be related to increasingly drier local conditions. A trend to stronger local evapotranspiration in recent decades is most likely linked to an increasing lack of effective rainfall. 

How to cite: Bejarano Arias, I., Nehme, C., Breitenbach, S. F. M., Meyer, H., Modestou, S., Pons-Branchu, E., and Mouralis, D.: A stalagmite-based multiproxy reconstruction of local environmental changes in the 20th century from Normandy, France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-853, https://doi.org/10.5194/egusphere-egu23-853, 2023.

The HIGH-PASM project studies the climate variability on the Island of Cyprus for the last millennium. We combine highly resolved speleothem records with archived weather data for the last 140 years in order to corroborate and understand climate signals recorded in speleothems over the last millennium. An active stalagmite of 8 cm length was collected from Hot cave in 2021 along with other secondary carbonate deposits from Lapithos Qanat, and Amiandos and Argaka Dam tunnels. U-Th dating and lamina counting were combined to produce an age model for Hot cave and Lapithos Qanat. 800 stable isotope measurements were conducted on the Hot cave stalagmite, 250 on the Lapithos sample and 45 on each of the Amiandos and Argaka deposits. Meteorological data collected since 1885 from four stations were consolidated and compared to the yearly resolved Hot cave and Lapithos records.

The Hot cave stalagmite grew continuously from 1330 to 2021 AD, the Lapithos sample covers the last 150 years and both Amiandos and Argaka deposits provide a continuous record for the last ca. 50 years. There is a general correspondence between the ẟ¹⁸O signal and precipitation peaks over the last 140 years, showing more negative ẟ¹⁸O values corresponding to times of high precipitation. The ẟ¹³C signal co-varies in general with ẟ¹⁸O, except during ~1970-1980, ~1930, ~1680, ~1650, ~1490, ~1400-1410 and ~1360-1370 AD. During these periods an anti-correlation is observed. During the 20^th century, periods of instrumental temperature rise are reflected by rising ẟ¹⁸O and ẟ¹³C values. A trend towards less negative ẟ¹⁸O values since 2000 AD is attributed to reduced rainfall amount and increased evapotranspiration as a consequence of steeply rising temperatures. During the instrumental period, the ẟ¹⁸O is a proxy of precipitation amount, and we assume that this relationship was valid for the last millennium. Strong temperature rises during certain intervals might also have affected the ẟ¹⁸O signal, reducing the sensitivity of this precipitation proxy.

Comparing the Hot cave record with global and regional records, periods with less negative ẟ¹⁸O values correspond generally to intervals of a negative NAO index and high total solar irradiance. Wet periods with more negative ẟ¹⁸O values correspond to intervals of a positive NAO index and low solar irradiation. The Hot cave record shows that the Little Ice Age (1300-1870 AD) begun with long dry intervals lasting until 1520 AD, followed by wetter intervals from 1520 to 1800 AD, and later followed by again long dry intervals until the present-day. The climate variability trend recorded in Hot cave during the last 700 years agrees generally well with the dry index reconstructed from tree-ring records in Troodos (Cyprus) and stalagmite data from Kocain cave in Southern Turkey

How to cite: Nehme, C., Kluge, T., Koltai, G., Edwards, R. L., Gucel, S., Ozden, O., Adjizian-Gérard, J., and Spoetl, C.: Climate variability from Hot cave (Cyprus) for the last 700 years: implications for speleothem proxies in determining long-term paleoclimate signals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9601, https://doi.org/10.5194/egusphere-egu23-9601, 2023.

The Pantanal is a large region located in the central parts of South America (140,000 km2) with a unique climate and vegetation setting. This region is subjected to seasonal floods, which makes the Pantanal one of the most important wetlands on the planet. In this region occur transitions between different biomes, such as the Amazon Forest, Cerrado (Brazilian Savanna), and Atlantic Forest, located to the North, East, and South of this region, respectively. The area also serves as a moisture pathway for the South American Summer Monsoon (SASM), which connects the Amazon Basin with the La Plata Basin. The two major drainage basins of South America. Due to the complex hydrology of the rivers and lakes of this region, it is necessary to combine multiple proxy archives from different parts of the Pantanal basin to understand its climate and vegetation evolution during the Holocene.

Here we present isotope records from stalagmites collected at sites located at the northern and southern borders of the Pantanal. Hiatuses in speleothem deposition during the mid-Holocene identified in several stalagmites indicate overall dry conditions in the region at this period. However, the drier conditions recorded in the northern portion of the basin precede similar conditions in the South by approximately two thousand years. Furthermore, summer insolation seems to drive the intensity of the SASM at the North Pantanal, while its influence is weaker in the southern part. During the late Holocene, this establishes a moisture gradient between a wetter North and drier South. Our record also shows a strong multidecadal to centennial variability, which was probably responsible for the high hydrology complexity of the rivers of the Pantanal, which are subject to seasonal floods and migration of its channels and tributaries.

How to cite: Novello, V., Ritzau, M., Cruz, F., Buehler, J., and Rehfeld, K.: Paleoclimatic and paleoenvironmental changes in the Pantanal region during the Holocene based on speleothem records, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3191, https://doi.org/10.5194/egusphere-egu23-3191, 2023.

The last glacial termination was marked by a series of millennial-scale hemispheric climate change events. One of the most prominent examples is Heinrich event  1, which was caused by ice-sheet instabilities of the Laurentide ice-sheet between 18,000-15,000 years ago (ka) and corresponding shifts in global climate. Recent speleothem oxygen isotope data suggest the presence of yet another much more abrupt and shorter event around 16 ka.  The global extent and the origin of this elusive 16-ka event have remained a mystery. Here we present new resolution clumped isotope data from a South Korean speleothem that shed new light on this phenomenon. Combined with LA-ICPMS trace element analysis, we demonstrate that the 16-ka event likely caused abrupt cooling over Eastern Asia of ~5-7^oC and massive shifts of both the winter and summer monsoon systems.  Using an isotope-enable earth system model, we show the observed oxygen isotope evolution is consistent with an abrupt meltwater lake surge into the North Atlantic, of unknown origin, with impacts on ocean stratification, sea-ice and northern hemispheric climate.

How to cite: Timmermann, A., Sinha, N., Jo, K., Wassenburg, J., Ruan, J., and Kim, H.: Abrupt cooling event over Asia due to North Atlantic climate instability ~16 ka, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2494, https://doi.org/10.5194/egusphere-egu23-2494, 2023.

A 22-cm long stalagmite (L2) from Lunnaya Cave (52º41’ N, 88º44’ E, 481 m a.s.l.) located in south Altai mountains of Russia was dated by AMS ¹⁴C because ²³⁰Th/U dating was not successful due to low U but high Th contents. The stalagmite grew since 19 kyr BP with very slow rate before 12 kyr BP and a growth hiatus during 5.5~7 kyr BP. A total of 1150 samples have been measured for δ¹⁸O and δ¹³C, revealing climatic and vegetation changes under the influence of Westerly, Polar Front and Siberian High. Although the δ¹⁸O trends show a depletion trend from early Holocene to middle Holocene, reached the lightest values between 7 and 8.5 kyr BP, and then an enrichment trend from 7 kyr BP toward the late Holocene, the δ¹⁸O trends are complicated for interpretation of climatic conditions. High-resolution (0.2-mm interval) scanning XRF Sr/Ca, Fe and Ti profiles illustrate that the weathering condition of overlying soil and limestone bedrock had significant change from pre-Holocene to late Holocene. The long-term trends of δ¹⁸O and δ¹³C records were related to moisture source and seasonal precipitation. Thus, both δ¹⁸O and δ¹³C records are needed to be de-trended in order to reflect precipitation amount effect and vegetation development, being negative values representing wet condition with more abundant vegetation, and vice versa. The growth hiatus of the stalagmite during 5.5~7 kyr BP was probably due to arid condition. Based on the δ¹⁸O, δ¹³C and scanning XRF elemental records, the climatic condition was very cold with only summer-month stalagmite growth during 19-13 kyr BP; cold and dry between 13-12 kyr BP (Younger Dryas); wet during 12-11.5 kry BP; mainly dry between 11.5 and 9.5 kyr BP; mainly warm and wet between 9.5 and 7 kyr BP. During 2.8~5.5 kyr BP, the climate was strongly fluctuated on centennial scales around an average condition. Dry climates were prevailed during 2.8~1.8 and 1~0.2 kyr BP, whereas wet climates were dominated during 1.8~1 and 0.2~0 kyr BP. The climatic conditions shown by the stalagmite agree well with the lake records in western and central Siberia.

How to cite: Li, H.-C., Chen, Y.-S., Blyakharchuk, T., Yin, J.-J., Mii, H.-S., and Shen, C.-C.: Climate and environmental changes during the past 19,000 years reflected d18O, d13C and scanning XRF elements of a 14C dated stalagmite from south Altai, Russia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1792, https://doi.org/10.5194/egusphere-egu23-1792, 2023.

Gibraltar climate is influenced by the Mediterranean Sea and the Atlantic Ocean in a boundary area between polar and subtropical air masses. Speleothem proxy records from Gibraltar caves provide opportunities to improve understanding of the long-term interplay of climatic features of this key location at the southern limit of tracks presently taken by the North Atlantic depressions delivering rainfall to Europe.

Deployment of logging instruments from 2004 to 2012 plus water and air sampling in two Gibraltar caves - St. Michaels and Ragged Staff - revealed that seasonality in speleothem growth rates is most strongly influenced by seasonally reversing convective ventilation that permeates the entire Rock. Average rates over longer timescales depend on drip rates (reflecting hydroclimate at the surface), combined with conversion into dissolved inorganic carbon of organic matter washed down by deep percolation into the epikarst and bedrock. The geochemistry of calcite precipitation is thus regulated by environmental conditions including net organic production by vegetation, temperatures and water balance. The monitoring results provide a robust foundation for palaeoclimate research. Data from twenty-four dated speleothems provide a palaeoclimatic framework with insights into regional climate as recorded by chemical proxies over seasonal to multimillennial timescales, over the last half-million years.

Here, we concentrate on the last glacial period and present a composite record based on four speleothems: two from near present sea level in Ragged Staff (Gib 10d and Gib 10e) and two (Gib 06a and Gib 06b) from an altitude of 255 masl in St. Michaels Cave. The composite chronology is constrained by over 170 U-Th dates and provides a continuous δ¹³O_calcite, δ¹⁸O_calcite and trace element proxy record of palaeoclimate from 100 ka to 10 ka, at a resolution that varies between ~5 and ~100 years. The Gibraltar δ¹⁸O record is strikingly similar to NGRIP but with a range of variation notably more subdued than other long speleothem records such as Soreq and Hulu that appear to have insolation forcing of monsoon strength as their dominant control. Our δ¹⁸O_calcite data show clear imprints of Alboran Sea SST associated with D-O cycles during MIS 2-5, superimposed on a general trend of higher δ¹⁸O during stadials and lower values in interstadials and interglacials. The latter trend may have multiple causes including changes in cave temperatures, ocean δ¹⁸O and isotopic disequilibrium during calcite deposition. Changes in atmospheric circulation are another possibility but currently difficult to evaluate as neither δ¹⁸O of individual rainfall events nor the GNIP monthly record show any relationship to modern synoptic circulation patterns. The δ¹³C record is interpreted as signaling changes in vegetation and water balance. Higher δ¹³C values are caused by greater degassing due to lower drip rates and/or weakened net organic matter production and downwash during cooler periods with less recharge. The trace element records across DO events provide supporting observations.

How to cite: Hoffmann, D. L., Mattey, D. P., Atkinson, T. C., Boyd, M., and Müller, W.: A Gibraltar speleothem record of environment and regional climate for the last glacial period, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12002, https://doi.org/10.5194/egusphere-egu23-12002, 2023.