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Reconstructing of past hydroclimates at regional scales during the Common Era (CE) is necessary to place the current warming in the context of natural climate variability. Here we present a composite record of oxygen isotope variations during last 2500 years based on eight stalagmites from four caves in the central Pyrenees (NE Spain) dominated by temperature variations, with the amount of precipitation playing a minor role. The dataset is compared with other Iberian reconstructions that show a high degree of internal coherence with respect to variability at the centennial scale. The Roman Period (RP) (especially 0–200 CE), the Medieval Climate Anomaly (MCA), and part of the Little Ice Age (LIA) represent the warmest periods, while the coldest decades occurred during the Dark Ages (DA) and most of the LIA intervals (e.g., 520–550 CE and 1800–1850 CE). Importantly, the LIA cooling or the MCA warming were not continuous or uniform and exhibited high decadal variability. The Industrial Era (IE) shows an overall warming trend although with marked cycles and partial stabilization during the last 2 decades (1990–2010). The strong coherence between the speleothem data, European temperature reconstructions and global tree-ring data informs about the regional representativeness of this new record as Pyrenean past climate variations. Solar variability, likely through its impact on the North Atlantic Oscillation, and major volcanic eruptions appear to be the two main drivers of climate in southwestern Europe during the past 2.5 millennia. [ABSTRACT FROM AUTHOR]

Ice caves are one of the least studied parts of the cryosphere, particularly those located in inaccessible permafrost areas at high altitudes or high latitudes. We characterize the climate dynamics and the geomorphological features of Devaux cave, an outstanding ice cave in the Central Pyrenees on the French–Spanish border. Two distinct cave sectors were identified based on air temperature and geomorphological observations. The first one comprises well-ventilated galleries with large temperature oscillations likely influenced by a cave river. The second sector corresponds to more isolated chambers, where air and rock temperatures stay below 0 ∘ C throughout the year. Seasonal layered ice and hoarfrost occupy the first sector, while transparent, massive perennial ice is present in the isolated chambers. Cryogenic calcite and gypsum are mainly present within the perennial ice. During winter, the cave river freezes at the outlet, resulting in a damming and backflooding of the cave. We suggest that relict ice formations record past damming events with the subsequent formation of congelation ice. δ34 S values of gypsum indicate that the sulfate originated from the oxidation of pyrite present in the bedrock. Several features including air and rock temperatures, the absence of drips, the small loss of ice in the past 7 decades, and the location of ice bodies in the cave indicate that the cave permafrost is the result of a combination of undercooling by ventilation and diffusive heat transfer from the surrounding permafrost, reaching a thickness of ∼ 200 m. [ABSTRACT FROM AUTHOR]

New speleothem records from northeastern Iberian caves provide data to explore the climatic patterns during the Holocene. We present δ13C and Mg/Ca from three speleothems from two different caves located in the Iberian Range allowing replication of the climatic signal for several millennia. Through the integration of those stalagmites covering since the Holocene onset to 2 ka, the early Holocene (11.7–8.5 ka) appears as the wettest interval. A marked change towards aridity is observed during the middle Holocene (8.5–4.8 ka) and an increase of humidity afterwards (4.8–2 ka). This three-part pattern, contrasting with other Iberian sequences, seems to be associated with the different role that seasonality has played in the response of different proxies (or records) to changes in water availability. Interpreting our speleothem records as changes in winter-spring precipitation along the Holocene allows reconciling previous data on hydrological variability from the western Mediterranean borderlands. [ABSTRACT FROM PUBLISHER]

We present a multi-proxy approach to reconstructing Holocene climate conditions in northeastern Spain based on an excellent correlation among the lamina thickness, colour parameters and isotope (δ18O and δ13C) variations recorded in a speleothem. An age model constructed from five U/Th dates and annual lamina counting suggests that the uppermost 14.7 cm of the MO-7 stalagmite grew between 7.2 and 2.5 ka before present but experienced a growth hiatus from 4.9 to 4.3 ka. Three spectral analysis methods were applied to 11 time series. The results reveal common solar periodicities on decennial (Gleissberg cycle) and centennial (De Vries-Suess cycle) scales. The onset of Holocene carbonate precipitation in the MO-7 stalagmite appears to be associated with a cold, wet period, whereas the hiatus and the end of growth are related to warm, dry periods. This environmental trend fits well within the regional Holocene climate. [ABSTRACT FROM AUTHOR]

The interpretation of stable isotopes in speleothems in terms of past temperature variability or precipitation rates requires a comprehensive understanding of the climatic factors and processes that influence the δO signal in the way through the atmosphere to the cave, where carbonate precipitates acquiring its final isotopic composition. This study presents for the first time in the Iberia Peninsula an integrated analysis of the isotopic composition of rainfall (δO) during 2010-2012 years and, through a detailed monitoring survey, the transference of the primary isotopic signal throughout the soil and epikarst into the Molinos cave (Teruel, NE Spain). Both air temperature and amount of precipitation have an important effect on δO values, clearly imprinting a seasonal variability modulated by an amount effect when rainfall events are more frequent or intense. Air mass history and atmospheric circulation influences are considered through the study of weather types, synoptic-scale climate patterns and large-scale atmospheric circulation indexes (North Atlantic Oscillation and Western Mediterranean Oscillation) revealing a dominant source effect on δO values in this region where tropical North Atlantic and Western Mediterranean are the two moisture source regions. A delay of 2-3 months occurs between the dripwater oxygen isotopic composition (δO) respect to δO values as a consequence of large residence time in the epikarst. Limited calcite precipitates are found from winter to spring when δO values are less negative and dripwater rates are constant. This study suggests that NE Iberian δO proxy records are best interpreted as reflecting a combination of parameters, not just paleotemperature or paleorainfall and, if extending present-day situation towards the recent past, a biased signal towards winter values should be expected in Molinos speleothem records. [ABSTRACT FROM AUTHOR]

• Unique 60-m thick clastic laminated cave record covering 71–26 ky. • New dating and palaeoenviromental inferences from Pyrenean glaciers. • Identification of two main glacier stabilization phases at ~30–36 ky and ~15 ky. • Backflooding due to the blockage of the cave entrance by the Ara glacier. In Alpine regions, speleothem development on karst systems largely occurs during warm interglacial or interstadial phases due to their limited growth during cold stages. Still, recent attention has been given to the role of clastic sediments in caves, less dependent on temperature conditions. Yet, only a small number of caves worldwide preserve both speleothems and detrital deposits. Here we present an outstanding record of fine-grain laminated sediments and carbonate speleothems from the Granito cave (South Central Pyrenees, Spain) associated with seasonal to annual hydroclimatic pulses through the Last Glacial Cycle (LGC). Analysis of cave clastic facies together with new absolute dates on glacial deposits along the valley has provided new insights into the karst-glacial interactions in relation with long-term landscape evolution, with support of geomorphological, sedimentological, mineralogical, palynological, geochemical and geochronological data (U/Th series, OSL and IRSL). The Granito cave was formed before 153.6±1.2 ky (Marine Isotopic Stage, MIS 6), as indicated by the oldest stalagmites dated in the cave, although speleothem formation occurred preferentially during MIS 5 and the Holocene interglacial stages. A 60 m thick clastic deposit was IRSL dated from 71.8±5.6 ky to after 26.5±2.5 ky corresponding with the maximum ice extent (MIE) during the LGC and subsequent glacial stabilization at 30.3±1.7 – 36.2±2.2 ky. The sediment infill was produced by water ponded in the cave coeval with the presence of glacial ice blocking the cave entrance. The cave clastic sequence includes channel, slackwater and backswamp facies, interpreted to result from pulses of sediment-laden water flow under vadose and phreatic flow regimes. The cave sediment's mineralogical composition points to an exogenous source associated with glacial till sediments overlying the hillslope above the cave and along the Ara River valley. The palynological results obtained from the cave sediments show the dominance of an open landscape composed of steppe vegetation indicating cold glacial climatic conditions. The opening of the cave occurred before 14.9±1.5 ky, the stabilization age of the innermost Ara glacier moraine, giving rise to scouring and cut-and-fill sequences within the detrital infill. Speleothem growth during the Holocene indicates the return to warm climatic conditions with the development of a soil and vegetation cover above the cave. This study shows how a combined interpretation of clastic and speleothem lithofacies is critical for elucidating landscape evolution and surface-groundwater palaeohydrological changes in northern Iberia during the LGC. [ABSTRACT FROM AUTHOR]