ABSTRACT Archaeologists studying the Late Pleistocene and Early Holocene records in the Southeast have made significant methodological and theoretical contributions to our understanding of the earliest Native American record. In this paper, we briefly review these contributions. We then present a geographic case study of the southern Lower Mississippi River Valley. Relying on border, behavioral ecological, and cultural transmission theories, we show that due to terminal Pleistocene environmental conditions, this region was only sparsely inhabited until the post-Clovis unfluted period (∼12,100 years ago) and not fully settled until San Patrice populations established the region as their homeland at the end of the Younger Dryas. During this settlement and emplacement process, the Mississippi River became a permeable but clear social boundary marker.

Theory and models suggest the Gulf Stream may shift northwards under projected Atlantic Meridional Overturning Circulation weakening. Yet Gulf Stream behaviour during past abrupt cold events remains poorly constrained. Here we present high-resolution paleoceanographic records from the Northwest Atlantic during the last deglaciation. During the Younger Dryas cold period, we document a northward Gulf Stream shift evidenced from coherent surface and subsurface warming. Our sortable silt data suggest a strengthening of upper North Atlantic Deep Water that opposes weakening lower North Atlantic Deep Water, consistent with a seesaw feedback between the Nordic overflows and subpolar gyre. Our results constrain a co-ordinated sequence at the Younger Dryas onset: initial lower North Atlantic Deep Water weakening and subpolar sea‑ice expansion, lagged (58 ± 38 yr) by an increase in upper North Atlantic Deep Water and an eventual atmospheric reorganization (84 ± 51 yr after onset). These findings provide empirical support for model projections of future Gulf Stream shifts.

Submediterranean marcescent oak forests form a climatic ecotone highly exposed to increasing aridity across the Mediterranean Basin. Understanding how these vulnerable taxa were affected by past climatic shifts can help contextualize their sensitivity to ongoing changes. Here we used ensemble Species Distribution Models (SDMs) to infer the distribution dynamics of eight marcescent oak species from the Heinrich Stadial (~ 17ka) to the present, and to explore their potential future trajectories for 2070 and 2100 under three SSP scenarios. Models calibrated with 12,450 filtered occurrences and high-resolution paleoclimate and CHELSA datasets performed well (AUC > 0.97), with precipitation and temperature seasonality emerging as key predictors. Hindcasts revealed contrasting east-west Quaternary histories, including episodes of expansion, contraction and partial stability linked to abrupt climate transitions such as the Heinrich Stadial and Younger Dryas. Future projections indicate widespread northward shifts and substantial suitability losses, especially under SSP5-8.5, with pronounced impacts on narrowly distributed taxa. By comparing past-to-present and present-to-future range shifts, we identify temporal coherence in species responses, showing that taxa with strong historical fluctuations tend to exhibit larger projected changes. Integrating past range dynamics provides an essential ecological baseline to interpret species-specific sensitivity and regional asymmetries. Our results refine the identification of potential climatic refugia and high-risk zones, offering a framework to prioritize conservation strategies for transitional oak forests in a rapidly warming Mediterranean Basin.

Several ice-dammed lakes formed between the Younger Dryas moraines and the Tana River valley during the retreat of the Fennoscandian Ice Sheet over northeast Norway. Drainage of these lakes left an indelible scar on the landscape; the Gaccetávži ravine, a feature over 10 km long and up to 120 m deep. Here, we use LiDAR-derived digital terrain models, alongside field investigations and novel remote sensing techniques, to propose a model for the formation, evolution, and eventual drainage of the lakes that led to the ravine's formation. Initially, four smaller lakes were established at the margin immediately after the Younger Dryas (YD), separated by ice overlying areas of higher relief. With marginal retreat, three lakes coalesced before breaking through an ice-dam to join with the fourth lake and form one large lake. At its greatest extent, the lake covered 59 km2 and held 1.7 km3 of water. The first breakthrough triggered an outburst flood and initiated the formation of the ravine. Subsequent periods of lake drainage occurred with ice-front oscillation and the opening of new spillways and outlet channels. This pattern is recorded in a succession of glaciofluvial terraces and erosional features around the ravine and south towards the Tana River.

We explore the mechanisms leading to the formation of the Disentis and Sedrun fans, which represent the largest and thickest Quaternary fan systems in the headwater area of the Alpine Rhine. These fans are several km 2 in size and underlain by tens of meters-thick, non-consolidated breccias. The sedimentary fabric of these deposits is matrix-supported, suggesting deposition by debris flows. In addition, concentrations of in-situ 10 Be in detrital quartz minerals that are embedded in these deposits reveal high paleo-denudation rates of nearly 2 mm yr −1 . These rates are substantially higher than the mean denudation rates <1 mm yr −1 that we measured for the headwaters of the Alpine Rhine. This confirms the view where the fan deposits at Disentis and Sedrun record a time interval when material supply occurred through sedimentary pulses. In addition, regional studies reveal that the construction of the investigated fan systems postdates the formation of moraines that were dated to the Egesen Stadial during the Younger Dryas. We thus propose that the accumulation of the sedimentary material at Disentis and Sedrun most likely occurred during the same epoch as the Flims rock avalanche. This was the largest mass failure event in the European Alps and resulted in the accumulation of tens of meter-thick, non-consolidated breccias on the valley floor some kilometers farther downstream. The result was the formation of a lake upstream of the rock avalanche deposits and the rise of the base level on the valley floor. We thus envisage an interpretation where the higher base level together with the release of large volumes of sediment caused the construction of the fans at Disentis and Sedrun. Once the lake was breached and the hillslope sediment reservoirs were exhausted, the Alpine Rhine started to incise into the previously deposited material, thereby leaving distinct cut levels at the toes of these fans. We acknowledge that we lack precise numerical ages for the time period when the fan systems at Disentis and Sedrun were constructed. Nevertheless, based on the available information, we conclude that the fan sediments in Alpine valleys serve as suitable archives for improving our understanding of the environmental response to climate warming. • We present 10Be-based paleo-denudation rates recorded by terrace deposits in the Alpine Rhine. • The results show that these sediments, which accumulated after the change from the cold period of Egesen Stadial to the Boreal warm period, record the occurrence of sedimentary pulses. • The accumulation of the sedimentary material at Disentis and Sedrun most likely occurred at the same time as the Flims rock avalanche, the largest mass failure event in the European Alps. • Based on our research, we consider that terrace sediments and breccia deposits in Alpine valleys as suitable archives for improving our understanding of the environmental response to climate warming.

Vegetation-hydrology coupling in subtropical China during the Younger Dryas: A quantitative reconstruction from high-resolution pollen records at Luoxiao Mountains

Preliminary Study on Depth of Thermocline (DOT) Changes in the Makassar Strait during the Younger Dryas Using Planktonic Foraminifera Abundance

The Younger Dryas (YD; ~12.9 to 11.7thousand years) marks an abrupt return to near-glacial conditions during the last deglaciation, yet its cause remains debated. One possible scenario, the YD impact hypothesis, proposes an extraterrestrial trigger. However, growing geochemical and stratigraphic evidence points toward a volcanic origin. This study presents the 187Os/188Os isotope and highly siderophile element (HSE) data from the Page-Ladson (PL) site (8JE591) in Florida, a well-dated, continuous sedimentary record spanning the YD onset. The onset in the PL profile is marked by unradiogenic osmium coincident with elevated Os and Re concentrations and a Cl-chondrite-normalized HSE pattern with a compositional range and signature closely matching volcanic aerosol patterns. When integrated with comparable records from Hall's Cave and the Debra L. Friedkin site in Texas, the unradiogenic 187Os/188Os ratios align across multiple depositional environments and correlate with a cluster of major bipolar volcanic eruptions (~12.98 to 12.87thousand years) documented in Greenland and Antarctic ice cores whose cumulative radiative forcing exceeds the most volcanically active intervals of the Common Era. The magnitude and hemispheric asymmetry of this volcanic activity imply forcing of sufficient magnitude capable of disrupting the Atlantic Meridional Overturning Circulation and triggering rapid Northern Hemisphere cooling. These findings provide multiproxy, regionally consistent evidence for a volcanically driven perturbation at the onset of the YD, offering a robust alternative to impact-based explanations.

Abstract The 14 C marine reservoir age in the North Atlantic and Norwegian Sea has varied through the late glacial period. Here I present a curve, called Norcoast25, for the calibration of late glacial and Early Holocene marine 14 C ages from the Norwegian coast. I also present a table of ΔR values that could be used for the calibration of 14 C ages with Marine20. The results are based on paired 14 C dates of terrestrial plant fragments and articulated marine shells found in shallow marine deposits on the outer coast of Western Norway. The shells calcified in marine water and the 14 C reservoir ages represent the surface water off the Norwegian coast. The ΔR value relative to Marine20 decreases from + 300 14 C yr at 14.4 cal ka BP to − 100 14 C yr at 14.2 cal ka BP and is constant throughout the Allerød. At the transition to the Younger Dryas (YD) the ΔR value increases, and reaches a maximum in the middle YD of + 80 14 C yr. At the YD/Early Holocene boundary, the ΔR value drops 200 14 C yr. These late glacial ΔR values from Norway’s west coast are 150–300 14 C yr lower than has been reconstructed from 14 C-dated sediment cores from the open ocean. The Norcoast25 calibration curve can be uploaded to the OxCal calibration program. A link to the file (Norcoast25.14c) is provided at the end of the paper.

Abstract The chronology of Late Glacial and Early Holocene dune formation and wildfire activity at the Łaskarzew site, eastern Poland, was reconstructed using a combination of accelerator mass spectrometry (AMS) radiocarbon dating ( 14 C) and optically stimulated luminescence (OSL) dating. The stratigraphic profile records 13 aeolian-soil cycles, characterized by alternating phases of aeolian deposition, soil formation, and wildfire episodes, reflecting the interplay between short-term climatic oscillations and aeolian processes. Radiocarbon dates were obtained from 26 charcoal samples embedded within palaeosols and charcoal horizons and calibrated using the IntCal20 curve, while OSL dating of quartz grains provided additional chronological control for aeolian sediments. The integration of these two dating methods established a robust timeline of environmental changes. The aeolian activity began during the Oldest Dryas and intensified during the Allerød interstadial, with four distinct wildfire events associated with rapid vegetation recovery and fire-prone landscapes. The Younger Dryas was marked by widespread aeolian deposition under arid climatic conditions, with no organic layers preserved. In the Holocene, nine independent wildfire episodes spanning approximately 4500 years were identified, linked to warm climatic conditions and the dominance of pine forests. Aeolian activity persisted into the Middle Holocene, accumulating nearly three meters of sediment before stabilizing around 7 ka BP due to increased vegetation cover. This study underscores the effectiveness of integrating radiocarbon and luminescence dating to resolve Late Quaternary chronologies, providing insights into fire-vegetation dynamics and aeolian processes within the European Sand Belt.

• Mid-depth Atlantic accumulated remineralised carbon and nutrients during HS1 and YD. • Coral δ 11 B and Ba/Ca reveal low-pH and nutrient enrichment events at 15.4 and 12.0 ka. • Coral Nd isotopes indicate persistent northern-sourced Atlantic waters. • Carbon and nutrient buildup linked to AMOC slowdown rather than Southern Ocean input. Atmospheric CO 2 and the temperature of the interior Atlantic Ocean both increased in 2-steps during the last deglaciation, particularly during Heinrich Stadial 1 (HS1; ∼16 ka) and the Younger Dryas (YD; ∼12 ka). However, what drove these punctuated rises remains a long-standing question. The role of deep-ocean carbon storage, release, and redistribution continues to be debated. To establish the role of ocean circulation in deglacial carbon and nutrient cycling, we present new multi-proxy data in sub-fossil corals from mid-depths in the Equatorial Atlantic, including boron isotopes (δ 11 B; seawater pH), Ba/Ca (seawater [Ba] and refractory nutrients), and neodymium isotopes (ε Nd ; provenance of seawater signal). Corals are dated to a precise radiometric age scale and combined with previously published radiocarbon and temperature proxy measurements on the same samples. Our data reveal abrupt intervals (∼500 years) of notably low pH, Ba-rich, and radiocarbon-depleted (old) waters at 15.4 and 12.0 ka during HS1 and the YD at depths of ∼1700 m. However, very low ε Nd (unradiogenic) values suggest that these corals were bathed in northern-sourced Atlantic waters throughout the deglaciation. These results imply that these (old) carbon- and nutrient-rich intermediate waters were not sourced from the carbon- and nutrient-rich Southern Ocean via Antarctic Intermediate Water (AAIW). Instead, carbon and nutrient accumulation at mid-depths in the tropical Atlantic was likely the result of remineralisation of organic matter at times of Atlantic Meridional Overturning Circulation (AMOC) slowdown. The Atlantic Ocean interior was therefore accumulating heat and carbon during these times when deepwater flushing was minimal, thus acting to partially dampen atmospheric CO 2 rise and warming caused by ventilation of the Southern and Pacific Oceans.

A 14 500-year multi-proxy reconstruction of climate and environmental change in Eastern Baltics

Reconstructing proboscidean diet and mobility during the Younger Dryas through isotopic evidence from the Colby site, Wyoming, USA

Glacial dynamics in the Outer Tropics reflects a complex interplay of variations in precipitation and temperature driven by large scale ocean-atmospheric dynamics. Cosmogenic dating of moraines, palaeoglacier reconstruction and comparison to climate proxies adds to our understanding of palaeoglacier dynamics in relation to these forcings and can help assess future changes of tropical glaciers in response to ongoing climatic changes. Here we present 12 cosmogenic 10 Be exposure ages from three moraines of the Mullucocha Valley in the previously unresearched Cordillera Pariacaca, Peru. These moraines tightly constrain three phases of glaciation in the central Peruvian Andes at 28.0 ka, 15.5 ka and 11.6 ka, attributed to the Last Local Glacial Maximum, Older Dryas and Late Pleistocene-Early Holocene transition, respectively. They add new evidence for the synchronous behaviour of Central Peruvian glaciers relative to the wider Outer Tropics, from the Lateglacial to Early Holocene. Following comparison with regional moraine chronologies, we suggest an early Last Local Glacial Maximum (LLGM) in Central Peru which occurred prior to the global LGM. A two-phase glacial maximum in the Outer Tropics at 28 ka and ∼22 ka is hypothesised. An undated moraine nested inside the LLGM moraine in the Mullucocha Valley is theorised to be representative of the younger 22 ka LLGM phase, closer to the timing of global LGM. The 15.5 ka moraine adds to the growing evidence of stabilisation during the Older Dryas, when cold northern hemisphere conditions enhanced precipitation in the Outer Tropics. The 11.6 ka moraine could be connected to the very Early Holocene or late Younger Dryas and is exemplary of a time of widespread moraine formation across the Outer Tropics. It represents a period of glacier stillstand within the wider post-LGM retreat, reflecting periods of cooler, wetter conditions within the overall warming trend. This study provides new insights into the glacial and climate history of the central Peruvian Andes and highlights the need for updated palaeoclimate reconstruction methods. • 10 Be is used to date three moraines in the central Peruvian Andes at 12°S. • Moraines are dated to 28.0 ka, 15.5 ka and 11.6 ka in Cordillera Pariacaca, Peru. • Early Last Local Glacial Maximum in central Peru is identified. • Glacial phases in central Peru broadly synchronous with rest of the outer tropics.

This study presents integrated Cladoceran, plant macrofossil and diatom-based environmental reconstruction from the Čepkeliai Bog (Southern Lithuania), covering the Late Glacial-Early Holocene transition. The objective was to assess palaeoenvironmental changes with a focus on trophic state, acidification, and water-level fluctuations and to explore the applicability of these assemblages as temperature-sensitive indicators. The findings of our study revealed that sedimentation started at about 13,200-13,000 cal yr BP in a deep, oligotrophic and cold-water palaeobasin. Inferred palaeoenvironment changes correlate with the GI-1b event (Gertsenzee oscillation). A significant ecological shift to a shallow, warm, ecologically diverse environment occurredat about 13,000 cal yr BP and is consistent with the GI-1a (Allerød) period. The Younger Dryas (12,850-11,650 cal yr BP) is characterised by a rise in lake level and oligo-mesotrophic and high-water transparency conditions. At the end of the Younger Dryas (around 12,000 cal yr BP), climate warming and a drop in water levels were recorded. Intensive palaeobasin swamping processes began around 9700 years cal yr BP, during the Boreal period. A short-lived "9.2" cooling event was fixed at about 9200-9000 cal yr BP. The results obtained provide new insights into postglacial palaeoenvironmental dynamics in the southeastern Baltic region.

In this paper, a synthesis is given of a large multi-disciplinary project, which included physical, botanical, zoological and archaeological studies, accelerator mass spectrometer (AMS) 14C and Optical Stimulated Luminescence (OSL) dating and chemical analyses from numerous locations in and along the extensive Moervaart palaeolake (NW Belgium), south of the Maldegem-Stekene Coversand Ridge. This rich dataset enabled a detailed reconstruction of climate, vegetation development and human presence in the period from the Weichselian Lateglacial and early Holocene. In addition, this dataset was used to make spatial reconstructions of the vegetation patterns in the direct surroundings of the Moervaart palaeolake for seven time slices and artist impressions for three moments in the archaeological record. These vegetation maps and the high resolution data on climate and the abiotic landscape are compared to former human occupation patterns to give insight in these early human presences in NW Europe. The first evidence for human presence, after a long period of absence, was found from the Allerød period. During this period, hunter-gatherers of the Federmesser culture were present in encampments along the northern shore of the Moervaart palaeolake which had developed during the Bølling period. Both the improving climate and the availability of a fresh water source stimulated human presence. The vegetation transitioned from a tundra landscape in the Bølling period to a boreal forest with birch and pine in the Allerød. During the following cold period of the Younger Dryas, forests retreated and tundra vegetation redeveloped. At the same time, the Moervaart palaeolake and most of the surrounding dune ponds turned dry. Evidence of human presence in the region during the Younger Dryas period is scarce, presumably related to the colder climatic conditions and the strongly reduced availability of fresh water sources. Due to climate warming during the early Holocene, boreal forests expanded again. However, evidence of human occupation of the area remains scarce. The Preboreal forest expansion was shortly interrupted by another cold reversal, the so-called Preboreal Oscillation or 11.4 event. After this event, hunter-gatherers returned to the area, then settling preferably along the dry banks of the Kale/Durme river, a tributary of the Scheldt river, which was the only source of fresh water in the region. During the following Boreal, coniferous forests were gradually replaced by deciduous forests which had developed initially with hazel, elm and oak, but later (Atlantic) also with lime, alder and ash. Hunter-gatherer site-density was highest during the first part of the Boreal, when hazel dominated the landscape. Afterwards, site-density dropped considerably; however, it is not clear whether this reflects a marked population reduction or rather points to changing mobility in response to a changing environment.

Abstract Lake sediments record past hydrologic variability, but natural lakes are often sparse in semiarid and arid regions, making the calibration of paleohydrologic models a challenge. At Lake Elsinore, the largest of the few natural lakes in Southern California, we explore and develop a novel transfer function approach for reconstructing lake depth. Using 32 modern surface sediment samples spanning Lake Elsinore’s littoral to profundal zones, we establish a statistical relationship between lake depth and sediment elemental geochemistry composition analyzed via X-ray fluorescence (XRF). We develop lake depth transfer functions using weighted averaging-partial least squares (WA-PLS) and modern analog technique (MAT). Application of the WA-PLS C5 elemental geochemistry-based transfer function to Lake Elsinore sediment cores reveals a climatically sensitive and variable lake hydrology over the past 32,000 years. The reconstruction suggests a prolonged shallowing during an early Marine Isotope Stage 2 (MIS 2) mega-drought between 28,000 and 25,000 cal yr BP, a deep lake spanning the last glacial maximum, a wet–dry response to the Younger Dryas, and a highly dynamic MIS 1/Holocene lake. This single-lake elemental geochemistry technique may be useful in similar settings for reconstructing lake depth and inferring past hydrologic changes.

Abstract Plant wax hydrogen isotopes (δ 2 H) preserved in lake sediments provide valuable insights into past climatic changes. However, lake catchments often experience local shifts in vegetation type that can yield distinct isotopic signatures in the sediments, potentially obscuring hydroclimatic signals. Here, we compile regional plant wax data and test different approaches to correct for the impact of changes in vegetation type over time to isolate precipitation δ 2 H values (δ 2 H prc ) since the Younger Dryas (12.9–11.7 ka) from a sediment record from Rotsee (central Switzerland). Our method intercomparison shows that n ‐alkane relative abundances produced the most accurate δ 2 H prc estimates, agreeing with an independent speleothem fluid‐inclusion δ 2 H record from Milandre Cave. This indicates that sedimentary plant wax δ 2 H values represent a vegetation‐weighted community signal. Precipitation was 2 H‐depleted during the Younger Dryas (∼−75‰), and then δ 2 H prc values increased sharply into the Holocene. During the early Holocene (∼10 ka), δ 2 H prc values of ∼−55‰ were reached, consistent with maximum summer insolation, followed by a gradual long‐term decline toward the present, reflecting Neoglacial cooling and consistent with modern δ 2 H prc values (∼−67‰). Importantly, while plant wax δ 2 H values declined sharply due to deforestation beginning in the Roman period, this impact is effectively corrected for by using the relative abundance of n ‐alkanes. These findings underscore the need for site‐specific vegetation corrections to produce robust hydroclimate reconstructions from plant‐wax isotopes, especially in lakes with small catchments, thereby enhancing comparability of sedimentary records with climate models and deepening our understanding of past climate–vegetation–human interactions.

Abstract Millennial‐scale climate variability punctuated the last glacial period around the globe, but its expression in the North American midcontinent is not well understood. This is due, in part, to the fact that only a small number of published speleothem time series document these events from this region, and that they surprisingly exhibit isotopically higher oxygen isotope values during North Atlantic cold periods (Greenland stadials (GS) and Heinrich stadials) than during time‐adjacent interstadials, opposite the modern positive correlation with air temperature. Here we present a composite stalagmite record from Cosmic Cavern (CC), central United States, that preserves evidence of environmental change from 54‐14 ka. Stalagmite stable carbon (δ 13 C) and oxygen (δ 18 O) isotope variations are coincident with millennial‐scale events in the North Greenland Ice Core Project (NGRIP) δ 18 O record. During North Atlantic warm periods, stalagmite δ 13 C values decreased by 2–3‰, interpreted here as predominantly reflecting elevated soil respiration rates driven by increased temperature. Stalagmite δ 18 O values also vary broadly in concert with the NGRIP record, and exhibit the previously identified inverse correlation to air temperature, shifting by 0.5–1.5‰ between GS and interstadials. The consistency of this relationship across the central United States suggests that it reflects the δ 18 O of precipitation rather than site‐specific secondary effects. Interstadial precipitation δ 18 O values were lower due to regional enhancement of mesoscale convective storm activity and/or enhanced glacial meltwater flux to the Gulf of Mexico, the region's primary moisture source. Changes in precipitation seasonality, identified through analysis of climate model simulations, may have also played a role.

Abstract The decline of dissolved oxygen (DO) in marginal sea ecosystems has been exacerbated by rising greenhouse gas concentrations and anthropogenic nutrient inputs. The northern South China Sea (SCS) has recorded multiple reductions in DO, making it an ideal region for studying the response mechanisms of magnetic minerals to DO under varying climatic conditions. Here, we reconstruct the variations in magnetic mineral characteristics, marine DO levels (V/Cr), productivity (Ba/Al and CaCO 3 ) and a nutrient proxy (P/Al) based on the northern SCS sediments over the past 16,000 years. The Younger Dryas (YD) interval was characterized by marked reductions in magnetic mineral content and DO concentrations, concurrent with a pronounced increase in productivity. Our results reveal that variations in magnetic properties were mainly driven by post‐depositional magnetite dissolution, rather than changes in sediment provenance. During the YD and the late Holocene, intensified East Asian Winter Monsoon‐driven oceanic mixing enhanced productivity in the northern SCS, reduced DO levels, and triggered near‐total magnetite dissolution. Under deoxygenated conditions, dissolved iron is converted into bioavailable forms, amplifying productivity through a positive nutrient feedback mechanism. Our results highlight the mechanisms of DO variations under varying climatic conditions in the northern SCS and the response of magnetic minerals to them.