Changes in the marine reservoir age (MRA) of the surface ocean are important information used for radiocarbon dating of marine sediment cores or archaeological artifacts. MRA changes are expressed relative to the atmosphere, and as such are dependent on the prevailing atmospheric radiocarbon calibration curve. The most recent estimate for evolving global average MRA for latitudes approximately <50 degrees is incorporated into the marine calibration curve Marine20. This curve was directly calculated from the atmospheric Delta C-14 record, IntCal20, using the carbon cycle box model BICYCLE, taking into account observed changes in the carbon cycle. These simulations did not consider changes in the strength of the Atlantic meridional overturning circulation (AMOC) related to Dansgaard/Oeschger and Heinrich events. A recent study using the successor BICYCLE-SE suggested that abrupt AMOC changes would lead to changes in MRA of less than 100 C-14 yr in the non-polar surface ocean (about <50 degrees). To better support previous model-based MRA and to further constrain the impact of AMOC changes on MRA, we here assess transient simulations of the last 55 kyr performed by two Earth System Models of Intermediate Complexity (EMICs), LOVECLIM and Bern3D, and compare them to the published BICYCLE-SE box model results and previous output from the Large Scale Geostrophic (LSG) ocean general circulation model (OGCM). The setups within this MRA model intercomparison (MRA-MIP) are not identical, but all models are forced by atmospheric CO2 and Delta C-14 to have the surface ocean carbon cycle state as close as possible to reconstructions. Simulations with abrupt AMOC reductions during stadials display a rise in MRA in the surface northern Atlantic (>50 degrees N) and the deep Atlantic, for example reaching 300-1250 and 500-1300 C-14 yr, respectively, during Heinrich stadial 1. We find that the changes in the mean non-polar surface MRA (<50 degrees latitude) during abrupt AMOC changes in LOVECLIM are also in the order of +/- 100 C-14 yr, while in Bern3D simulated changes are up to +/- 200 C-14 yr. While the models tend to agree that a reduced AMOC leads to lower MRA by about 100-300 C-14 yr in the low-latitude surface ocean, under some conditions the opposite is found (e.g. simulations with LOVECLIM across Heinrich stadial 1). Spatially resolved results of the models show that changes in surface MRA during stadials depict the general pattern of a radiocarbon bipolar seesaw (older surface water in the high north, younger in the high south and in the Indo-Pacific), in agreement with previously published reconstructions. However, some model-dependent differences remain in the non-polar Atlantic. Throughout the last 50 kyr, the change in the multi-model mean in non-polar MRA of the two EMICs when compared with Marine20 is less than 100 C-14 yr and within the uncertainties of Marine20. Furthermore, changes in the MRA of the high latitude Southern Ocean (>50 degrees S) are extremely model-dependent and, for much of the period between 18 and 43 kyr BP, the changes in the multi-model mean MRA are larger than the 95 % confidence interval of the non-polar MRA depicted in Marine20. These differences make the construction of a numerical model-based calibration curve for the high latitude Southern Ocean challenging.

Since the first measurements of beryllium 10 (10Be) in ice, in the seventies, numerous profiles of this cosmogenic isotope have been obtained both in Antarctica and Greenland. In this article, we focus on Antarctic data, available at nine different sites, covering a significant part of the Holocene, from 237 to 7101 yr BP. We show that correlating their 10Be profiles allows to synchronize these ice cores with an excellent accuracy and to document the spatial variability of 10Be concentration and flux. We then examine how this variability is taken into account by a simulation of 10Be fallout recently performed with the ECHAM6.3-HAM2.3 model. Except for a systematic underestimation of 10Be fluxes at high accumulation sites, these simulations are overall very satisfying. Finally the excellent accuracy of synchronisation based on 10Be profiles allows us to derive an Antarctic stack record over the last seven millennia. The reliability of the new 10Be stack is demonstrated by its superior correspondence with the accurately dated IntCal20 record based on 14C in tree rings.

Extreme solar particle events (ESPEs) are caused by rare, enormously strong solar eruptions and can produce globally detectable spikes in tree-ring radiocarbon 14C, known as Miyake events, which serve as precise chronological tie-points and indicators of extreme solar activity. After production, radiocarbon is subjected to the complex carbon cycle, including large-scale atmospheric transport, which is crucially important for fast and strong Miyake events with highly inhomogeneous 14C production. A new 3D dynamical model, SOCOL:14C-Ex, of the radiocarbon atmospheric production and transport is presented here, which can model fast changes in the 14C atmospheric concentrations with high temporal and spatial resolution. Precise response curves of Δ^14C to a reference ESPE (100xGLE#69) were computed for various event dates. They can be directly applied to analyse Miyake events under different conditions. Seven strong events over the past 14 millennia (AD 993, AD 774, 664 BC, 5260 BC, 5411 BC, 7177 BC, and 12351 BC) were analysed by fitting the reference curves to the available annual D14C data, identifying the most probable values and confidence intervals of their parameters – strength, event's date and background level. By applying corrections for the geomagnetic and atmospheric (CO2) factors, the strengths of the corresponding ESPEs were assessed. The strongest ESPE is confirmed to be that of 12351 BC, while that of AD 774 remains the strongest event during the Holocene. To conclude, a new tool, based on the radiocarbon atmospheric transport model SOCOL:14C-Ex, is presented to analyse fast changes in the ^14C production.

We present high-resolution 10Be concentration and flux records from the Talos Dome ice core (East Antarctica), covering the period from 170 to 270 ka BP, to assess the capacity of Antarctic ice cores to capture the dipole moment reductions triggered by geomagnetic excursions of different amplitudes. Three distinct geomagnetic events are identified in the 10Be flux. The dipole collapse linked to the Iceland Basin Excursion (IBE) is clearly recorded as a 10Be peak flux 1.59 to 2.08 times above background between (192.0 +/- 1.4) ka BP and (185.6 +/- 1.4) ka BP. A clear asymmetric structure is observed, with a rapid decline of the geomagnetic dipole, followed by a three-step recovery. Two dipole decreases of lower amplitude are also resolved in relation with the Pringle Falls Excursion (PFE), lasting from (218.5 +/- 1.90) to (206.0 +/- 0.8) ka BP, and the Mamaku Excursion (ME), identified at (242.0 +/- 0.3) ka BP, both showing an increase of the 10Be flux by a factor of 1.24 to 1.63. A total of 40 short-term 10Be concentration minima were also identified and are consistently associated with peaks in major ion concentrations, indicating post-depositional effects that affect concentration but not the longer-term flux signal. Comparison with Dome Fuji ice core and oceanic authigenic 10Be/9Be records reveals strong agreement in the timing and structure of the dipole moment collapses linked with these excursions. These results further support the use of 10Be for synchronizing ice and marine archives as well as to reconstruct past geomagnetic dipole moment variations and refining age models over the Pleistocene.

The field vole, an abundant and widespread microtine rodent, is a complex comprised of three cryptic species: the short-tailed field vole (Microtus agrestis) which is present over much of Eurasia, the Mediterranean field vole (Microtus lavernedii) in southern Europe, and the Portuguese field vole (Microtus rozianus) in western Spain and Portugal. Previous research has shown high genomic differentiation of these three lineages. However, the details of the process underlying their divergence remain unknown. We analyse 70 mitogenomes and 16 nuclear genomes of modern specimens, and 83 mitogenomes and 12 nuclear genomes of ancient specimens spanning the last 75 thousand years (ka). We estimate the divergence of Portuguese from short-tailed and Mediterranean field voles to be ca. 220 ka ago and of the latter two species to be ca. 110 ka ago, earlier than previous estimates involving only modern sequences. The divergence times we obtain match those between major mitochondrial lineages of cold-adapted and steppe rodents in Europe. We find signatures of gene flow within and between field vole lineages, with some analyses suggesting a hybrid origin of the Mediterranean lineage. Ancient specimens from the Italian Peninsula reveal a previously unrecognised lineage that show evidence of genetic exchange with other populations. The pattern of genetic variation in the field vole species complex demonstrates the impact of stadial-interstadial cycles in generating recurrent episodes of allopatry and connectivity of populations, a situation which could only be revealed by our dense genomic sampling over time.

Exposure to excess UV-B radiation can harm organisms through DNA damage and oxidative stress, and has likely been a key ecological and evolutionary driver throughout Earth’s history. Here, we show UV-B at Earth’s surface was significantly increased during the Laschamps Event, the last major geomagnetic excursion ca. 41ka BP. During the Laschamps, we find significant and prolonged (lasting >600yrs) increases in UV-B absorbing compounds in subfossil Pinus Diploxylon pollen (e.g., 31% [95% CI 19-44] increase compared to 1.3ka BP). Furthermore, we identify a significant (negative) broader linear relationship (p<0.001) between UV-B absorbing compounds and the geomagnetic dipole moment extending over the past 65ka. Our results demonstrate an empirical link between surface UV-B and geodynamo strength, important for understanding our past and mitigating our potential future.

The central Congo Basin is home to the world's largest tropical peatland complex and is covered with swamp forest. In the face of climate change and future human activities in the region, it is important to understand the factors that determine the nature and dynamics of the peatland vegetation cover. One way to gain insight into these factors is to reconstruct the history of the central Congo Basin peatlands. Analysing lipid biomarkers extracted from peat cores such as plant wax n-alkanes enables past environmental and climatic conditions to be reconstructed. However, there is currently no information on how the production of plant waxes by different plant species influences the abundance and isotopic composition of n-alkanes in peat and other archives in the Congo Basin. In this study we analysed plant wax n-alkane abundances, delta C-13 and delta D values according to photosynthetic pathways (C-3 vs. C-4), angiosperm subclasses (dicotyledons vs. monocotyledons), and source water delta D values in the dominant plant types (trees, shrubs, and herbs) in the peatland area of the Cuvette Department in the Republic of the Congo. Our dataset enables the definition of a new n-alkane distribution index, named GRIND, that distinguishes between C-3 (mostly dicotyledons) and C-4 (monocotyledons) plants as follows: (n-C-27 + n-C-33 + n-C-35)/(n-C-25 + n-C-27 + n-C-29 + n-C-31 + n-C-33 + n-C-35). This index may therefore be used to analyse Central African peat deposits and derive the relative abundance of C-3 and C-4 plant waxes in the past, independently of delta C-13 measurements. Furthermore, delta C-13 values from the central Congo Basin and other African sites suggest that environments with high relative humidity (> 80%) are characterised by very negative delta C-13 values (i.e., < -37 parts per thousand) of n-C-29 and n-C-31 alkanes. This observation highlights the potential of n-alkane delta C-13 in deriving climatic information under high relative humidity conditions in Central African lowlands, and contribute to palaeo-climatic reconstructions. Finally, the delta D values of n-C-29 and n-C-31 alkanes demonstrate that, despite contrasting apparent fractionation values associated with photosynthetic pathways and plant functional types - which can be accounted for using delta C-13 and pollen data in sedimentary deposits - they reliably reflect the delta D of environmental water. This confirms that plant wax n-alkane delta D values are effective tools for reconstructing palaeo-climatic changes in equatorial regions.

The reservoir age of waters and carbon sequestration increased in the deep Atlantic Ocean during the last glacial period. The glacial northern deep water (GNADW) formation reached shallower depths than during the ensuing interglacial, and the underlying southern-sourced bottom water (GAABW) was filling the basin, generally poorly ventilated. The mechanisms within the deep ocean that facilitate the flip from glacial-to-interglacial modes are as yet to be understood. Here we present analysis performed on foraminifera (benthic δ13C, abundance of oxygen-tolerant benthic species and 14C age difference between benthic and planktonic species), together with the n-hexacosan-1-ol index (biomarker of the oxygenation of the deep-sea floor) in three deep cores at the Atlantic Iberian margin (ca. -5,000 m depth; 40°N). The locations selected follow the pathway of the Northeast Atlantic Deep Water (NEADW): MD03-2698 (Tagus Iberian margin), D219 (Rincão da Pomba) and MD13-3473 (Tore inner basin). Additionally, results of polar northern and southern sites (U1308 and TN057-21 respectively) are discussed as a reference for evaluating long-distance connections. The hypothesis to be tested is whether the deep waters off Iberia were northern- or southern-sourced during the deglaciation within the Tore seamount, a crater-shaped geological structure, 300 km off the Iberian continental shelf. It includes an inner basin down to -5,500 m, isolated from the oceanic basin by a summit rim at -2,200 m. The external connection with the Atlantic is by two narrow NW and NE gateways down to –4,300 m. This makes the area a singular spot to decipher the NEADW-end member of the Atlantic deep circulation. We find benthic (Cibicidoides wuellerstorfi) δ13C values around 0 ‰ in the interior of the Tore before 18 ky, slightly heavier than those known from shallower Iberian sites (ca. -3,500 m). This points to isolation of the Tore basin from the influence of GAABW. This contrasts with the other sites MD03-2698 and D219 which record δ13C around -0.6 ‰, similarly to TN057-21 values. Inside the Tore, benthic foraminifera species grouped according to their oxygen tolerance are oligotrophic during the glacial (oxygen-rich, more ventilated conditions) and mesotrophic over the Holocene (intermediate ventilation).The carbon residence time measured in MD03-2698 and D219, as estimated from the 14C age difference between benthic and planktonic foraminifera, confirms previous reservoir ages in the deep Iberian margin (MD99-2334K; JC89-SHAK03-6K, JC89-SHAK05-3K). In the inner basin (MD13-3473), the estimation is not valid, probably due to increased bioturbation, lower sedimentation rates and mixing turbiditic flow. The hexacosanol index marks the lowest ventilation pattern culminating around 16 ky (MD03-2698, D219), an apparent inflection point from when the ventilation shifts from southern to northern sourced deep waters, the former not registered in the inner Tore (MD13-3473). This occurs in line with a large reduction in the Atlantic meridional overturning circulation (AMOC) and maximum extent of ice sheets. Taken together, interactions between atmospheric, marine, cryosphere and terrestrial climate elements, as recorded by different proxies during the stadial multi-step structure associated within Heinrich event 1 (H1.1) are giving clues to the processes bringing about deglaciation.

Variations in Total Solar Irradiance (TSI) have long been hypothesized to influence global mean surface temperature (GMST) on centennial to millennial timescales, but empirical evidence for this relationship has remained elusive. Focusing on the pre-industrial Holocene, when anthropogenic influences were minimal, we apply Convergent Cross Mapping (CCM), a causal-inference method, to explore the link between solar variability and climate. We analyze four combinations, pairing two temperature targets (a global mean surface reconstruction and a central-Greenland site record (GISP2)) with two TSI reconstructions, across a broad range of timescale configurations. Our results indicate that TSI had a discernible impact on temperature variability for about 80% of parameter choices, with stronger, but less consistently significant evidence of influence on GISP2 and consistently significant, but weaker evidence regarding the global mean. This contrast suggests that although solar forcing was not the dominant driver of Holocene climate fluctuations at the global scale, its influence is still detectable and may provide a useful benchmark for evaluating whether models correctly capture the nonlinear dynamics of Earth’s climate.

Little is known about the impact of the Mediaeval Warm Period (MWP: 950-1250 CE) and the Little Ice Age (LIA: 1250-1850 CE) on high-altitude agro-pastoral practices and the vertical mobility of human communities in the mountain regions of interior Southwest Asia. Although the area experienced significant socio-political changes during the last millennium, the socio-environmental interactions during these climatic periods remain poorly understood. This study presents a geochronologically well-constrained, multi-proxy geochemical and palaeoecological record from a high-altitude (2500 m) wetland in the Karkas Mountains, located on the central Iranian desert plateau. All proxies, including bioindicators (pollen, non-pollen palynomorphs, fossil insects) and sedimentological and geochemical data (X-ray fluorescence intensity variations, Isothermal Remanent Magnetization measurements, and lithological changes), reveal two contrasting patterns of hydroclimatic conditions and agropastoral practices during the MWP and the LIA. Pollen and non-pollen palynomorphs show that the MWP was characterised by intensive cereal cultivation (mainly wheat) and the establishment of permanent agricultural communities, while the LIA was characterised by intensified grazing pressure on montane steppe vegetation, suggesting a shift towards a more mobile pastoral lifestyle-one that persisted into the 20th century. Interestingly, this shift coincides with the Mongol invasion of the Iranian plateau. Variations in lithology, XRF intensities, magnetic field as well as the insect faunal assemblages further provide insights into the wetland hydrological variations and erosional episodes related to land-use and hydroclimatic changes during the MWP and LIA. Based on the Gahak wetland record and regional palaeoclimatic data, we conclude that the MWP in the mountainous areas of central Iran was marked by milder winters and possibly shorter summer droughts, in contrast to the LIA, which had harsher winters and longer-lasting snow cover. Results of the spectral analysis on Gahak record compared to well-known solar cycles, suggest that the climate of the central Iranian highlands is highly sensitive to the variations in solar irradiance. Our findings highlight the significant role of high-altitude agro-pastoral communities in supplying food to the lowland urban centres of mediaeval Persia, at least during the MWP. Although socio-political changes (e.g. Mongol invasion) could affect the mediaeval societies, the impact of climatic shifts on socio-economic changes should not be underestimated.

This study reconstructs the fluvial dynamics of the Bras de Fer distributary in the Rh & ocirc;ne Delta (France) during the Little Ice Age (LIA) in response to short-term climatic forcing. A multiproxy approach combining historical cartography, sedimentology, geochemistry, magnetic susceptibility, and hydrological archives reveals accelerated meander migration and extensive overbank accretion between the late seventeenth and early eighteenth centuries CE. Increased flood frequency, coinciding with positive phases of the Atlantic Multidecadal Oscillation (AMO+), promoted rapid lateral channel shifts and the formation of crevasse splay complexes along the outside bank of the Grande Ponche meander. The results demonstrate that, despite stable relative sea levels, deltaic morphology remained highly sensitive to decadal-scale climatic variability, highlighting the dominant role of hydrological extremes in shaping fluvial-deltaic environments of Rh & ocirc;ne delta during the late LIA.

Late Pleistocene hydroclimate variability in Central America and its associated climate forcings are poorly constrained. The region is influenced by complex ocean-atmosphere-continent interactions, and documented palaeohydrological responses, which vary by site and/or proxy specificity, are far from conclusive. We used delta D of n-alkanes from a marine sediment core in the Panama Basin to infer past changes in precipitation over the last 56 kyr. Our results indicate a progressive intensification of precipitation during the last glacial period, culminating in a precipitation maximum during the Last Glacial Maximum (LGM, 23-19 kyr BP), followed by a rapid decline during the Heinrich Event 1 (H1, 18-15 kyr BP) time interval. While the regional pattern of the precipitation anomaly during the LGM is proxy and site dependent, the regional drying during H1 shows a clear north-south signature associated with the southward meridional migration of the Intertropical Convergence Zone (ITCZ). Using iTrace and PMIP4 model simulations, we show that the precipitation changes associated with the ITCZ shift are closely linked to the equatorial SST front induced by changes in the oceanic circulation. We propose that an increase in this latitudinal SST gradient could have locally pushed the ITCZ further north, bringing rainfall to southern Central America during the LGM.

Extremely thinned layers and possible folding make the dating of the deepest sections of ice cores especially challenging. Cosmogenic radionuclides have the potential to provide independent age estimates. The 36Cl/10Be ratio is largely independent of production rate changes that affect individual radionuclides and has an effective half-life of 384 kyr, making it an ideal tool for dating the new 1.5 Myr old ice core that the Beyond EPICA Oldest Ice Core project aims to retrieve at Little Dome C in East Antarctica. However, the loss of 36Cl through hydrogen chloride outgassing at low accumulation sites complicates its application and the long-term decay of the 36Cl/10Be ratio in ice has not been studied. Here, we show that 36Cl is preserved in glacial periods and that the 36Cl/10Be ratio decreases more slowly than expected from physical decay over the last 900 kyr. While the glacial 36Cl flux decreases at the expected rate of physical decay within the uncertainty, the 10Be flux decreases faster, which maybe linked to a post-depositional mobility of 10Be in deep ice and leads to the slower decrease of the 36Cl/10Be ratio. In addition to this long-term trend, the 36Cl/10Be ratio fluctuates around a fitted decay curve, which is likely caused by different climate sensitivities of the transport and deposition pathways of the individual radionuclides. Both effects need to be better understood and quantified to improve age estimates based on the 36Cl/10Be ratio.

Alpine lakes in the Mediterranean region are experiencing rapid warming, posing a threat to aquatic ecosystem diversity and functioning. Documenting how high-altitude lake ecosystems have responded to past warming and cooling events is of interest to scale modern changes in a long-term context, and to inform management strategies. This paleoenvironmental study focuses on Lake Petit (2200 m a.s.l., Southern Alps) and combines the analysis of subfossil diatoms and inorganic and organic sediment composition over the last 14,000 years. The results show a major ecosystem shift at the Late Glacial-Holocene transition, ca. 12,000 years ago. In addition, the alternating dominance of diatoms from the Fragilariaceae (e.g., Pseudostaurosira pseudoconstruens, Staurosira venter) and Gomphonemaceae (e.g., Gomphonema elegantissimum), along with high-amplitude fluctuations in biogenic silica concentrations, highlight rapid ecological shifts at four distinct periods: 10,100–9800, 9200–9000, 8100–8000, and 7000–6900 cal yr BP. These shifts reveal the occurrence of four centennial-scale cooling events at the beginning of the Holocene. During the warmer Middle-Holocene period, diatom assemblages are dominated by Staurosirella neopinnata, ending with a shift coinciding with the 4.2 ka climate event, described in a previous study. A progressive return of S. neopinnata is observed nowadays. Our findings suggest that during the Early Holocene, the lake ecosystem was capable of buffering centennial-scale cooling events, consistently returning to previous conditions. However, the two phases of major long-lasting ecological shift that occurred 7000 and 4200 years ago, likely driven by catchment-related factors such as pedogenesis and vegetation dynamics, led to stepwise changes in ecosystem functioning baselines. This paper raises once again questions about the capacity of modern aquatic high-altitude lake ecosytems to recover from ongoing climate change when local baselines are no longer in equilibrium with natural variability.

A commonly-used approach to estimate changes in the frequency of past events or the size of populations looks at variations in the rate of archaeological and environmental samples (e.g., charcoal from fires, human/animal bones, or other evidence of occupation) found at a site over time. Time periods with large numbers of samples suggest increased activity, while those with few samples indicate a reduced level of activity. Variations and abrupt changes in the rate of observed samples might suggest the influence of important external environmental factors. This paradigm is known as “dates-as-data”. The reliability of such a “dates-as-data” approach is highly dependent upon our ability to estimate the calendar ages of the discoveries. Most archaeological/environmental dates are obtained using radiocarbon (14C). All 14C determinations need to be calibrated in order that they can be understood on the calendar scale. This introduces considerable uncertainties in the resultant calendar ages and complicates the identification of changepoints in the calendar year rates at which samples occur. In this talk, we provide a statistically rigorous approach to overcome these challenges. We model the occurrence of events (each assumed to leave a 14C sample in the archaeological/environmental record) as an inhomogeneous Poisson process, estimating the varying rate of samples using reversible-jump Markov Chain Monte Carlo. Given a set of radiocarbon samples, we aim to reconstruct how their occurrence rate varies over calendar time and identify if there are statistically significant changepoints in the rate at which the samples arise (i.e., specific times at which the rate of events abruptly changes). We will demonstrate our approach on data exploring the expansion of humans, and the parallel disappearance of megafauna, in the Yukon and Alaska in the late Pleistocene and early Holocene: investigating both the timings of such migrations in comparison with the climatic changes known to have occurred during this period, and the potential interactions between humans and the various species in the region.

Cosmogenic nuclides such as beryllium-10 (10Be) and chlorine-36 (36Cl) are valuable tools for dating deep ice cores and reconstructing paleomagnetic events. These nuclides are formed through interactions of target atoms in the atmosphere with galactic cosmic rays and deposited on ice sheets in aerosol form only and aerosol and gaseous forms for 10Be and 36Cl, respectively. However, questions persist regarding the preservation of their production signals in deep ice cores. In particular, low snow accumulation rates favour H36Cl migration and outgassing from the snowpack (Delmas et al., 2004; Pivot et al., 2019).Here, we present new measurements of 10Be and 36Cl in the Talos Dome ice core, focusing on periods older than 170 ka BP. When corrected from the radioactive decay of 36Cl and 10Be, a 36Cl/10Be ratio of 0.125 is observed, consistent with ratios observed during the last 700 years in the Talos Dome ice core. The 36Cl/10Be ratio generally overestimate the reconstructed age compared to those expected from AICC2023 chronology (Bouchet et al., 2023). Thus, the consideration of climatic and chemical concentrations is necessary to correctly apply the 36Cl/10Be ratio as a dating tool.Additionally, 10Be and 36Cl fluxes record past Earth magnetic field variations. We identify the Iceland Basin geomagnetic excursion around 190 ka as a clear stratigraphic marker, associated with a near doubling of the 10Be and 36Cl fluxes compared to background levels. By contrast, evidence for the Pringle Falls excursion(s) is less apparent. This different observation suggests that only the most intense excursions can be recorded in East Antarctic ice cores. This conclusion is of importance for future consideration of Beyond EPICA ice samples for investigating excursions and inversions after 800 ka.Overall, our findings underscore the good preservation of atmospheric cosmogenic nuclide signals in the Talos Dome ice core, reinforcing their utility for dating deep ice and investigating paleomagnetic events.

A commonly-used paradigm to estimate changes in the frequency of past events or the size of populations is to consider the occurrence rate of archaeological/environmental samples found at a site over time. The reliability of such a "dates-as-data" approach is highly dependent upon how the occurrence rates are estimated from the underlying samples, particularly when calendar age information for the samples is obtained from radiocarbon (14C). The most frequently-used "14C-dates-as-data" approach of creating Summed Probability Distributions (SPDs) is not statistically valid or coherent and can provide highly misleading inference. Here, we provide an alternative method with a rigorous statistical underpinning that also provides valuable additional information on potential changepoints in the rate of events. Our approach ensures more reliable "14C-dates-as-data" analyses, allowing us to better assess and identify potential signals present. We model the occurrence of events, each assumed to leave a radiocarbon sample in the archaeological/environmental record, as an inhomogeneous Poisson process. The varying rate of samples over time is then estimated within a fully-Bayesian framework using reversible-jump Markov Chain Monte Carlo (RJ-MCMC). Given a set of radiocarbon samples, we reconstruct how their occurrence rate varies over calendar time and identify if that rate contains statistically-significant changes, i.e., specific times at which the rate of events abruptly changes. We illustrate our method with both a simulation study and a practical example concerning late-Pleistocene megafaunal population changes in Alaska and Yukon.

Western European climate during the Last Glacial period (50-20 ka BP) was shaped by complex interactions between oceanic and terrestrial conditions, modulated by both orbital and millennial-scale forcings. This study integrates 75 marine and terrestrial palaeoenvironmental records to reconstruct spatiotemporal climate variability across Europe and the Mediterranean region. Sea surface temperature (SST) records reveal a pronounced latitudinal gradient, with strong cooling at high latitudes and relative SST stability at mid-latitudes on multimillennial timescales, which likely moderated western European climate. Pollen-based vegetation records, in contrast, show a steep longitudinal trend, with intensified environmental shifts southeast of the Alps, where oceanic moderation was limited. On millennial timescales, Dansgaard-Oeschger cycles and Heinrich stadials imprinted distinct signatures on SST and vegetation, especially near the Atlantic margin, linked to disruptions in the Atlantic Meridional Overturning Circulation. These findings highlight the differentiated sensitivity of oceanic and terrestrial conditions to climate drivers and the climatic role of geographic barriers such as the Alps. The resulting spatial heterogeneity likely influenced human cultural trajectories, with stable long-term conditions but strong Heinrich stadial near the Atlantic coinciding with the emergence of the Chatelperronian industry, while more pronounced climatic long-term trend in southeastern Europe paralleled the development of the Uluzzian complex. This integrated palaeoenvironmental framework provides critical context for interpreting Late Pleistocene human adaptation and innovation in Europe.