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Ciénegas are desert wetlands that are strongly correlated with the stability of the hydrologic cycle in arid landscapes. However, these environments are particularly vulnerable to climate change, drought, water diversion, and fire suppression which all have contributed to the degradation of ciénegas along the U.S.-Mexican borderlands. Therefore, identifying the timing of precipitation patterns in this region is of particular interest because of its relationship to many ecological responses of the landscape such as groundwater recharge and fire. Here, we present the first-ever fire paleoenvironmental record from Ciénega Chimeneas, a ciénega complex in the Sierra de Juárez of Baja California. We explore how changes in the amount and seasonality of moisture affected ciénega complexes and fire activity from across the southwestern North American region over the past 45,000 years. Our record suggests that during the late glacial period, 41,000–21,000 cal yr BP, the increase of Larrea and Quercus indicate an increase in summer precipitation. Subsequently, when summer precipitation increased, pollen preservation and pollen accumulation rates (PAR) also increased. Increased vegetation allowed for increased fire activity during the late glacial period. Regionally, most of the comparison sites also indicated wet conditions during the full glacial period. However, around 21,000 cal yr BP, effective moisture decreased resulting in a dramatic change in the vegetation assemblage. Specifically, the summer wet taxa disappeared, while pollen preservation and PAR decreased, suggesting a dry period until ∼14,000 cal yr BP. Little fire activity is recorded after 21,000 cal yr BP, likely due to the absence of fuels. At ∼14,000 cal yr BP, Larrea and Quercus reappear suggesting increased summer precipitation. However, the appearance of Cyperaceae and increases in grasses suggest increased winter precipitation. We suggest that the combination of summer wet and winterwet taxa ∼14,000 cal yr BP represents an increase in ENSO conditions, while the summer moisture controls remained relatively constant. [ABSTRACT FROM AUTHOR]

The Yarlung Tsangpo River on the southern Tibetan Plateau flows between alternating broad shallow valley and deep gorge sections. Many damming events caused by glaciers or glacial moraines have occurred in the gorges during the last glacial period, which play an important role in shaping river landscapes. In this study, we used geomorphological, sedimentological and chronological techniques to analyze the dammed paleolake in the Shan'nan-Gyaca stretch of the middle reaches of the Yarlung Tsangpo River. Four sedimentary sections were studied, delineating three major lithofacies associations. We also summarized previous research. Our results suggest that the paleolake was formed before ∼16 ka BP and drained at ∼10 ka BP, developing at least two deltaic-lacustrine sedimentary cycles. The paleolake's highest water surface was ∼3620 m above sea level, with a minimum area and volume of ∼140 km2 and ∼86 km3, respectively. The dam located at the entrance of the Gyaca Gorge may have been formed by glacial moraines during the Last Glacial Maximum; the subsequent outburst event had probably triggered a megaflood downstream. [ABSTRACT FROM AUTHOR]

Loess and paleosols are valuable terrestrial archives of past climate change in arid and semiarid Asia, yet most of the available records are located in central Asia and China, with only few records from western Asia. Here we report on a loess-paleosol sequence retrieved from the Gorgan Plain Southeast of the Caspian Sea that extends back to ca. 27,000 years ago. By combining palynological and micromorphological data with granulometry and magnetic properties in different horizons, we infer past changes in soil formation and vegetation composition, and the related climatic conditions. In order to set up a more reliable chronological framework, we applied luminescence and radiocarbon dating. Our results suggest a dry and cold glacial period characterized by steppe vegetation and loess deposition until about 24,000 years ago. Climate conditions during the Last Glacial Maximum (19–23,000 years ago) were relatively wet followed by a drying trend towards the end of the deglaciation. Our record suggests a relatively wet early Holocene but remains inconclusive for the late Holocene due to concurrent anthropogenic impact. We argue that changes in wintertime temperature and precipitation have been decisive in shaping the vegetation and soil formation in our study area during the Holocene, whereas changes in the position of the westerlies together with sea-level fluctuations of the Caspian Sea controlled the regional climate during the last glacial period. [ABSTRACT FROM AUTHOR]

The Larsemann Hills, near Prydz Bay is a key region to understand past glacial dynamics in East Antarctica. However, multi-proxy dating constraints for this area indicate an uncertain chronology for deglaciation history during the Last Glacial Period (LGP). In this paper, we report two 26Al exposure ages and eighteen 10Be exposure ages for bedrock samples to better understand past glacial histories. The minimum exposure ages range from 82.84 ± 4.67 ka to 15.1 ± 1.95 ka corresponding to Marine Isotope Stages (MIS) 5–2, and fourteen of these samples date from before the global Last Glacial Maximum (c. 19–26.5 ka). Analysis of 10Be and 26Al concentrations implies a complex deglaciation history, and surface lowering of bedrock may have caused systematic age underestimation. Further comparisons between two adjacent regions in the Mirror Peninsula reveal two major deglaciations involving the Lambert Glacier / Amery Ice Shelf System dated at 61.78 ka to 82.84 ka and 21.98 ka to 49.5 ka during the LGP. • We present new evidence for studying glacial history of Larsemann Hills, Antarctica. • Cosmogenic nuclides 10Be and 26Al dating method is applied for better analysis. • Two major deglaciation events occurred regionally within MIS 2–3 and MIS 4–5. • The exposure age and elevation show a highly significant positive correlation. • Multi-proxy and adjacent evidence are summarized and compared with this study. [ABSTRACT FROM AUTHOR]

Long-term changes in vegetation cover of the Tibetan Plateau (TP) are essential for understanding vegetation change under future climate. Previous studies have mainly concentrated on the Holocene and the eastern region of the TP, but here, we establish a relationship between modern pollen data (including both pollen percentage and concentration) and vegetation cover using a random forest (RF) model based on 362 soil-surface samples from the TP, as well as using it to quantitatively reconstruct the vegetation cover history of the Dagze Co (central TP, covering the last 19.5 cal. ka BP) and Koucha Lake (eastern TP, covering the last 33.8 cal. ka BP) regions. The RF results indicate that both the models based on pollen percentages or concentrations perform similarly (former: R2 = 0.538, RMSEP = 19.772%; latter: R2 = 0.540, RMSEP = 19.723%). However, when considering the reconstructed vegetation cover of Dagze Co and Koucha Lake, the results based on pollen concentrations appear to be more reliable. Before 13.4 and 16.8 cal. ka BP, Dagze Co and Koucha Lake has low vegetation cover of 25% and 30%, respectively, dominated by alpine desert or desert steppe. After that, changes in vegetation cover show different trends. At Dagze Co, the vegetation cover reaches a high level (54%) between 13.4 and 5.3 cal. ka BP, followed by a decrease until it starts increasing again at 2 cal. ka BP, in response to the change in the Indian Summer Monsoon (ISM). At Koucha Lake, the vegetation cover fluctuates at around 60%, indicating less sensitivity to climate change. Our research highlights the importance of pollen concentrations in quantitatively reconstructing past vegetation cover and the sparse vegetation status during the LGM on the TP. • Vegetation cover history on the central and eastern Tibean Plateau was reconstructed based on pollen concentrations. • Alpine desert or desert steppe with sparse vegetation cover was widely distributed during the LGM on the Tibetan Plateau. • There are significant spatial and temporal differences in vegetation cover on the central and eastern Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Trough mouth fans (TMFs) are major submarine depocentres that form in front of ice streams advancing onto the continental shelf, and they provide extensive records of past glaciations and ice-sheet dynamics. However, early research about TMFs was conducted using primarily 2D seismic data, which limits the insights on the deposit's geometries and internal structures and more recent studies using 3D data have focused on the general depositional history of TMFs. Here, we assess the spatial and temporal changes of the glacio-marine landforms and deposits throughout the last glacial-interglacial cycle (Marine Isotope Stage (MIS) 6 to 1, ∼130 ka to present) recorded in a >550 m thick progradational sequence. We use 3D reflection seismic data with significant vertical resolution (up to 2 m) imaging over 14000 km2 from the uppermost North Sea Fan (NSF) to document the seismic stratigraphy and sedimentary processes, by combining horizon picking and geomorphological analyses. The studied interval comprises five mappable units, four on the slope and one on the shelf, spanning from the modern seabed down to the top of the Tampen Slide (∼130 ka). Five different channel types (here included slide scars), as well as contourite and plumite packages are described based on their seismic facies, morphology, geometry, and stratigraphical position. We propose that contour currents are responsible for sediment delivery after the Tampen Slide deposition during the interglacial period before the onset of the Last Glacial Maximum, when high meltwater influx from the shelf produced turbidites. Sedimentation became debris-flow-dominated towards the end of the period of shelf-edge glaciation. The deglacial interval is characterized by the deposition of plumites on the slope. On the shelf, subglacial tills are deposited during both glacial and deglacial periods. We calculate an average sedimentation rate of <1 m/kyr during the interglacial (MIS 5-3), and around 50–65 m/kyr during the glacial and deglacial periods (MIS2-early MIS1). Thus, we document a change of two orders of magnitude in sedimentation rate during a glacial cycle on the slope of a glaciated margin. • 3D seismic imaging of the Late Pleistocene deposits of the North Sea TMF. • The geological record includes the sediments of a full glacial-interglacial cycle. • Contourites on the slope (interglacial) accumulated with an average rate of 0.7 m/kyr. • Glacial and deglacial periods have much higher sedimentation rates (65 and 50 m/kyr). • Shift from meltwater turbidites to debris flows during the shelf-edge glaciation. [ABSTRACT FROM AUTHOR]

The middle reaches of Yarlung Tsangpo, situated on the southern Tibetan Plateau, have experienced extensive river damming events due to glacier advances, resulting in the formation of several ancient dammed lakes. These palaeolakes offer invaluable insights into past hydrological and geomorphological dynamics on the Tibetan Plateau. In this study, we reported a newly identified ancient dammed lake, named the Xiaru palaeolake, located upstream of the Ganglai Gorge in the uppermost segment of the middle reaches of Yarlung Tsangpo, and conducted a pioneer chronological investigation of the lake using K-feldspar post-IR IRSL (pIRIR) dating. Quartz minerals from most lacustrine and fluvial sediments can not provide reliable ages characterized with low intensity and large inter-aliquot scatter in equivalent doses (D e). In contrast, the K-feldspar exhibited much greater luminescence intensity and narrower D e distribution using the pIRIR 225 dating protocol. Residual, dose recovery, and fading tests demonstrated that the pIRIR 225 signals are well bleached with a relatively low fading rate, making it a more suitable dosimeter for dating applications in the study area. The pIRIR 225 ages, derived through single aliquots, standard growth curve (SGC), and single grain measurements, reveal a major phase of the Xiaru Lake between 24.1 ± 1.0 ka and 15.8 ± 1.1 ka, that commenced aligning with the global Last Glacial Maximum. Furthermore, one lacustrine sample dated to 29.9 ± 2.2 ka suggests the possibility of multiple damming events in Ganglai Gorge during the last glacial period, although further evidence is required for a comprehensive interpretation. [ABSTRACT FROM AUTHOR]

The New Guinea Highlands were among the first areas where agricultural societies developed about 9 kya. Even today, the highest human population densities can be found in the tropical highlands, those are the most important shelters for societies in this seriously malaria-affected equatorial area. In this study, the distribution and altitudinal patterns of Plasmodium vivax and Plasmodium falciparum malaria, as well as the potential generation numbers and the annual season lengths of the extrinsic transmission periods of the parasites were modelled for the Last Glacial Maximum, the Mid-Holocene Period, 1960–1990 and 2061–2080 in the Papua New Guinea Highland provinces. It was found that areas influenced by Plasmodium vivax malaria have always been larger than the endemic regions of Plasmodium falciparum. After the Last Glacial Period, the extension of the malaria-free areas decreased dramatically. It could trigger the development of agriculture in the highlands in the early Holocene due to the increasing population concentration in malaria-free areas. These malaria-free regions could be stable in the rest part of the Holocene, which could explain the high human genetic and cultural diversity of the New Guinea Highlands. Future models predict the disruption of this stability and the notable decrease of the malaria-free areas in the highlands, especially in the case of Plasmodium vivax malaria, but the upward move in the Plasmodium falciparum -endemic regions also seems to be notable. These changes can negatively affect the demographic stability and cultural complexity of the traditional highlander communities in Papua New Guinea. [ABSTRACT FROM AUTHOR]

Atmospheric warming and circulation reorganization at the end of the last ice age represent the most important climate change of the last 100,000 years and provide an opportunity to uncover how the southern subtropics cryosphere responded to strong changes in the global climate system. Extensive mapping and chronologic records on cryogenic landforms to better understand the association and interactions between glaciers and viscous creep of ice-rich permafrost landforms (rock glaciers) are widely missing in the region. In this paper, we reconstruct the geomorphic imprint of the Last Glacial Maximum (LGM) and the Termination I in the high Andes of the Río Limarí Basin (30–31°S) in the subtropical semiarid Andes of Chile. 74 new 10Be surface exposure dating ages constrain the timing of glaciation, deglaciation, and glacial to periglacial transition. Glacial advances occurred first by 41.2 ± 0.6 – 35.0 ± 0.5 ka during Marine Isotope Stage 3, but probably earlier also; then, a second advance occurred during the global LGM between 24.2 ± 0.4 and 18.6 ± 0.2 ka. Deglaciation by 17.6 ± 0.2 ka left extensive hummocky moraines on the main valleys. Characteristic patterns of furrows and ridges typical of rock glaciers and solifluction superimposed on the LGM hummocky moraine indicate ice-rich permafrost in glacial deposits likely between 15.5 ± 0.3 and 13.6 ± 0.3 ka. We propose that moraines deposited by LGM debris-covered glaciers served as a niche for strong seasonal frost and permafrost creep, which substantially modified the original landforms. Our results contribute to a better understanding of major transformations in an ice-rich high mountain area of the southern hemisphere where the interplay of temperature and precipitation changes drove glacial to periglacial transitions. [Display omitted] • 74 new 10Be dates constrain the age of glaciation and periglaciation in the Limarí Andes. • Glaciers expanded between 24.2 ± 0.4–18.6 ± 0.2 ka in correspondence with the LGM. • Deglaciation with steady ice retreat and thinning was completed by 17.6 ± 0.2 ka. • LGM debris-covered glaciers left a moraine niche for subsequent rock glacier development. • Ice-rich permafrost reworked LGM moraine deposits between 15.5 ± 0.3–13.6 ± 0.3 ka. [ABSTRACT FROM AUTHOR]

Characterizing the ecosystems' response to environmental changes on Tibetan Plateau (TP), as well as elucidating the regional disparities of these changes across the plateau's surface and its neighboring regions, holds significance for safeguarding the ecological security of Asia. Here, an improved pollen-based biomization procedure, incorporating weighted taxa, was conducted to illustrate the spatial and temporal differences of vegetation changes in TP, Xinjiang and southwestern China over the past 21,000 years. Results showed that the vegetation changes in TP and Xinjiang were characterized by alternations among herbaceous biomes, while the southwestern China were featured by changes among various woody biomes. Asynchronous vegetation change rates (ROCs) were discovered among TP, Xinjiang and southwestern China. The ROCs in TP were generally low during the Last Glacial Maximum but rose abruptly and peaked in the late deglacial period, whereas Xinjiang and southwestern China had high and increasing ROCs during Holocene. Those trajectories might relate to different sensitivities of vegetation to climate change and human disturbances. Habitat limitation on TP should be pretty intense during glacial period, leading to rapid vegetation establishment after glacier retreat. While in Xinjiang, water availability was the most obvious limitation, making the vegetation change sensitive to moisture and atmospheric CO 2 variations. The forest in Yunnan behaved the most stability but was characterized by vertical migration responding to deglacial warming. Holocene acceleration of ROCs aligned with intensified human activities in Xinjiang and southwestern China. To sum up, environmental conditions have been always important in determining post glacial vegetation changes in west China, but the ROCs were asynchronous due to different sensitivities of vegetation to climate change and human activity. Although the plateau's vegetation was quite stable during Holocene, the plateau terrestrial ecosystem may subject to increasing risk under accelerating global warming and intensifying human activities. • An improved taxa-weight biomization was conducted to reconstruct vegetation history in west China since 21ka BP. • Rate of change and random forest reveal vegetation dynamic and its main driving factors. • Different sensitivities of ecosystems to climate change and human activity caused the trajectories in vegetation change. [ABSTRACT FROM AUTHOR]

Methane release into seawater and the atmosphere as a result of cold seepage activity is a sensitive indicator of global environmental change during the last glacial period. However, the link between postglacial ocean methane escape and possible increases in atmospheric methane concentration remains unclear, which hinders the evaluation of methane impact on climatic variability. In this study, lipid biomarkers were analyzed on samples from the Shenhu area in the South China Sea to reconstruct the marine gas hydrate variability since the last glacial time. The reconstructed methane release during the cool Last Glacial Maximum and Younger Dryas agreed well with previous findings. Interestingly, our results identified a pronounced methane outgassing at the end of Heinrich 1, which was likely triggered by the abrupt increase in intermediate water temperature. The occurrence of this gas hydrate dissociation before the drastic rise in atmospheric methane during Bølling-Allerød implied that the change in the gas hydrate reservoir could likely indirectly contribute to the initiation of the warming event, though more global evidence needs to be provided in the future. • Proxies in S11 marks the last glacial and deglacial methane release. • Increase of intermediate water temperature triggered deglacial methane release. • Marine gas hydrate dissociation contributed to the initiation of the warming event. [ABSTRACT FROM AUTHOR]

In the piedmont of uplifting mountains, alluvial fan rivers undergo significant aggradation-degradation processes, which are usually attributed to climate change. An ongoing debate is whether this process requests the participation of glaciation. To address this debate, we need the knowledge of the quantitative relationship between the ratio of water to sediment flux (q w / q s) with the aggradation/degradation process. This study examined the aggradation and degradation processes in three alluvial rivers at the piedmont of the Qilian Shan (Shan referes to Mountain) and simulated the river processes by a one-dimensional numerical model based on the transport-limited principle. Along the studied piedmont rivers, field measurements show a magnitude of 120–200 m degradation and aggradation in the Late Pleistocene. Through simulation analysis, we explored how factors like the ratio of water to sediment flux (q w / q s), channel width, and sediment grain size influence river processes and longitudinal profiles, and found distinct morphologies in different processes, where aggradation is characterized by concave-up profiles, while degradation is characterized by convex-down profiles. Additionally, the water flux is inversely proportional to the time required for the river to reach a new equilibrium profile. The simulated degradation amplitude aligns closely with the measured data in the Qilian Shan, indicating that precipitation during the Last Glacial Maximum in the region amounted to approximately ∼32% of the Holocene precipitation. This supports the notion that changes in water flux or precipitation alone can induce significant piedmont deepening without the necessity of glaciation. • Built a model to quantify the link between water-sediment fluxes and river processes. • Simulated Qilian Shan piedmont river incision: ∼32% LGM precipitation vs. Holocene. • Precipitation alone can create deep canyons without requiring glaciation. [ABSTRACT FROM AUTHOR]

Little information is available about the origin of loess on the Iranian Loess Plateau and along the northern foothills of the Alborz mountain range. Our well-dated multiproxy record from the Chenarli loess-paleosol sequence (LPS) fills this gap and provides a valuable paleoclimate record. Eight loess units are identified , covering the late penultimate glacial period (Marine Isotope Stage (MIS) 6: 135.6 ± 9.5 ka) until the Early Holocene (9.8 ± 0.7 ka). Geochemical results propose a constant local primary loess source with a longer transport distance only for MIS 5b and MIS 5d loess. However, low Si/Ti but high Zr/Ti ratios and increased sand contents of MIS 6 loess are implying stronger winds and derivation of this loess from a different source containing coarser particles. We interpret our data in a regional context and compare periods of loess deposition and pedogenesis in northern Iran with other loess records from Southern Eurasia. This indicates that late Pleistocene pedogenesis recorded at Chenarli agrees with periods of paleosol formation at LPS from northern Iran and Southern Eurasia. A ∼9-m thick loess deposition between ∼62 and 16 ka in unit 2 at Chenarli is consistent with other loess records indicating significant loess accumulation during MIS 3 with a peak during the Last Glacial Maximum in Southern Eurasia. One of the paleosols at Chenarli correlates with the late MIS 4 interstadial, which is well-recorded in southern Eurasian loess deposits. The geochemistry of loess and paleosols at Chenarli provides new information about the origin of loess in north and northeastern Iran where the sources of eolian deposition are still not well understood. • Eight loess units are identified spanning the past 135 ka, separated with paleosols. • Geochemical results indicate a constant local primary loess source for all loess units in the section. • Results indicate a longer transport distance from sources for MIS 5b and MIS 5d loess. • Particle size and geochemical data suggest that nearby sources with local sand contributions for MIS 6 loess. [ABSTRACT FROM AUTHOR]

Previous paleo-glacial studies on Kerguelen showed a singular pattern of Holocene glacier evolution on this archipelago in comparison with other southern mid-latitude glacier records. In this study, we aim to test this singularity on a longer timescale, based on 26 new in situ -produced 36Cl ages from pre-Holocene glacio-geomorphic features. Samples from moraine boulders and glacially polished bedrock were extracted at six different sites, located near the Port-aux-Français scientific station (PAF site), on Longue Island, Australia Island, on the Port-Jeanne d'Arc Peninsula (PJDA site), on the Gallieni Peninsula at Baie Larose (BLR site) and the McMurdo Island. The moraine ages indicate that glacier culminations occurred during Marine Isotopic Stage 3 (MIS 3) at 42.2 ± 4.9 ka on the PAF site, and during the global Last Glacial Maximum (gLGM) at 21.5 ± 3.2 ka on the PJDA site and at 21.4 ± 3.7 ka and 19.4 ± 2.6 on Baie Larose site. This is the first time that Late Pleistocene glacier culminations are evidenced on Kerguelen by direct moraine dating, thus allowing comparison with other moraine records from the southern mid-latitudes. While it remains speculative whether or not the MIS 3 glacial maximum at ⁓42.2 ka is in phase with other glaciers at this latitude (due to high age uncertainties), the gLGM glacial maximum is synchronous with that in other southern mid-latitude regions. 36Cl CRE ages of glacially polished bedrock surfaces sampled in different locations of the archipelago vary from ⁓39 ka to ⁓19 ka. We interpret these results as reflecting periods of deglaciation that occurred in between the two glacier culminations and right after the gLGM on Kerguelen. These ages also suggest that some places of the archipelago were free of ice at least since ⁓ 39 ka. The presence of a MIS 3 moraine at PAF site that has not been obliterated by a gLGM advance suggests that the ⁓ 42.2 ka glacier extent was at least as large as gLGM glacial maxima on the archipelago. The glacier culmination during MIS 3 being larger than that during the gLGM on the Kerguelen Archipelago matches observations in other southern mid-latitude regions. Late Pleistocene glacier culminations on Kerguelen may have been in phase with cold temperatures recorded in SST records, which suggest a cooling around Kerguelen. However, climate drivers responsible for the larger MIS 3 glacier culmination on Kerguelen still remain unclear even if we hypothesize that changes in precipitation may have superimposed on temperature changes. • We investigate glacier evolution on the Kerguelen Archipelago for the past 45 ka. • Glacier chronologies are based on 26 new 36Cl ages from moraines and bedrocks. • Preserved moraines attest to glacier culminations at ∼42 ka and during the LGM. • Evidence of larger MIS 3 than gLGM glacier culmination. • This pattern matches records from other southern mid-latitude regions. [ABSTRACT FROM AUTHOR]

• Glacial iceberg versus deglacial meltwater plume discharge in the Labrador Sea. • Enhanced Irminger Current may have affected ice sheet retreat. • A polynya probably occurred south of Greenland during the Last Glacial Maximum. The study of the history of ice sheet retreat provides important insights into the interaction between ice sheets and oceans, especially under a sustained warming climate. The decay of ice sheets may affect the surrounding ocean environment, and changes in sea surface conditions can, in turn, affect the ice sheet stability. However, interactions between ice sheet dynamics and sea surface characteristics are still not fully understood. Here, we show sedimentary records from the eastern Labrador Sea, proximal to the Laurentide Ice Sheet (LIS) and the Greenland Ice Sheet (GrIS). These records span the last 50 ka, i.e., the last glacial-deglacial-Holocene period. The XRF, biomarker, and planktic/benthic foraminifer data document the collapse of the LIS/iceberg discharge during Heinrich Events (i.e., HE5, HE4, HE2, and HE1) and the occurrence of meltwater plumes from the GrIS and the LIS during the last deglaciation. Such meltwater discharges have caused surface freshening in the Labrador Sea and, consequently, decreased sea surface temperatures and open-water phytoplankton productivity. Enhanced Irminger Current inflow might have caused (sub-)surface warming in the Labrador Sea and triggered the retreat of ice sheets/meltwater discharge. In contrast to relatively low primary production during the glacial period, the Last Glacial Maximum was characterized by increased sea ice algae and phytoplankton production, suggesting the presence of a polynya in front of the southern GrIS. [ABSTRACT FROM AUTHOR]

The Greater Khingan and Yanshan mountain ranges in northern China not only constitute a significant physical obstacle to the northward movement of monsoon circulation, but also represent a natural barrier for human migration and cultural interactions between in-migrating Paleolithic populations and those indigenous to East Asia during the Late Pleistocene. We dated two Paleolithic sites, Yangzhuangxishan and Taiziling, located in the southern piedmont of the Yanshan Mountains with artifacts typified by simple core and flake technology associated with foraging populations, to ∼39–29 ka and ∼ 52–47 ka respectively, using the optically stimulated luminescence dating method. Our results indicate that northern China as far south as the Yanshan Mountains was occupied mainly by autochthonous East Asian Paleolithic populations using a core and flake lithic technology, although during this period Initial Upper Paleolithic (IUP) modern humans and Mousterian populations dispersed into East Asia. By synthesizing and integrating the ages of Northeast Asian Paleolithic sequences during the last glacial period (ca. 70–10 ka), we analyzed spatio-temporal variations in Late Pleistocene human populations during relatively cold stadial events (MIS 4 & 2) and warmer interstadials (e.g., MIS 3), revealing an "ebb and flow" pattern for migrations of Western IUP/Mousterian populations and indigenous core and flake technology populations in East Asia corresponding to the advance and retreat of the East Asian monsoon regime. The subsequent extremely cold climate phase engendered a major population shift during the Last Glacial Maximum (ca. 26.5–19 ka) which drove the reduction of both these Paleolithic populations, but afterward facilitated the emergence and rapid dispersal of microlithic technologies in East Asia. The peoples associated with microlithic technologies achieved their maximum geographical extent after the Bølling-Allerød Late Glacial interstadial event (ca. 14.7–12.9 ka) and then gradually decreased, perhaps due to the development of agriculture after ∼13 ka with concomitant increasing settlement stability. • Two Paleolithic sites on the Yanshan Mountains were dated using OSL method. • Migrations of Western and indigenous populations correspond to monsoonal fluctuations. • The cold LGM climate engendered a major population shift. • Microblade populations decreased after ∼13 ka due to initiation of agriculture. [ABSTRACT FROM AUTHOR]

• The Irrawaddy River and Ganges-Brahmaputra rivers are the main sediment sources of the northern Ninetyeast Ridge over the last 50 kyr. • Millennial-scale periodic changes of weathering and terrigenous input are revealed during the last glacial period. • Shift of depositional center from Bengal Fan to the continental shelf is controlled by sea level changes. The Ninetyeast Ridge is situated within the world's largest sediment "source-sink" system, which extends from the Tibetan Plateau to the Bay of Bengal (BoB). Modest and stable sedimentation rate makes it a suitable region for studying long-term land-sea interaction. Recent research has primarily focused on the northern Bengal Fan, leaving limited knowledge about sedimentary processes on the distant Ninetyeast Ridge. This study aims to address this gap by investigating sediment transport pattern and its response to climatic and environmental changes since the last glacial period, using the gravity core (CJ04–50) selected from the northern Ninetyeast Ridge. The provenance discrimination based on δEu-(Gd/Yb) N revealed that the Irrawaddy (Irr) River, along with the Ganges-Brahmaputra (G-B) Rivers, represented the primary sources of the study area. Quantitative analysis equations indicated that the contribution of the G-B Rivers decreased from the last glacial period (22%) to the Holocene period (16%), while that of the Irr River increased (from 78% to 84%). Chemical index of alteration (CIA*) values, and terrigenous input proxy indicators (Ti/Ca, Rb/Sr) were used to indicate the changes of weathering and terrigenous input over the past 50 kyr. During the last glacial period, CIA*, Ti/Ca and Rb/Sr revealed significantly millennial-scale periodic changes, including the distinct declining trend during the Last Glacial Maximum (LGM) and Heinrich 2–4 (H2-H4) periods, followed by recovery trend during subsequent warm periods. During these cold periods of LGM and H2–H4, weakened Indian monsoon condition, reduced precipitation, cold climate, and expanding ice sheets, adversely affected physical erosion and chemical weathering in the source area, and the reduced river runoff impeded sediment transport. Conversely, these environmental factors reversed during relatively warm periods. Since the Holocene, CIA*, Ti/Ca and Rb/Sr declined, which was contrast to the climate change, and the sea level changes became the dominant factor. The rapidly rising sea level submerged the main terrigenous input channel (the Swatch of No Ground) of the G-B Rivers, made the depositional center shift from the Bengal Fan to the continental shelf, causing the decline of terrigenous input and lower CIA* values. [ABSTRACT FROM AUTHOR]

The East Antarctic Ice Sheet (EAIS) is the largest glacial system in the world, and the evolution history of the EAIS strongly affects global climate change. As one of the most extensive ice-free areas in coastal East Antarctica, the Larsemann Hills represent an important site for understanding the glacial evolution of East Antarctica. Generally, the last exposure process in the Larsemann Hills was considered to occur in the last glacial period. However, the initial time of the last exposure process in the Larsemann Hills remains unclear. This study presents the 10Be exposure ages of eight bedrock samples with glacial striae, which means that the original uneroded surfaces are preserved, from the Larsemann Hills and neighboring areas. The 10Be exposure ages ranging from 70.7 ± 4.7 to 13.5 ± 1.2 ka indicate that the Larsemann Hills have become ice-free since MIS4. The 10Be exposure ages with the characteristics of zonal distribution in the E–W direction and ages generally change from north to south, which reveals the combination of glacial retreat and topography differences. The activity of the ice sheet in the Larsemann Hills did not respond to the Last Glacial Maximum (LGM). In contrast, the deglaciation in the Larsemann Hills occurred as a diachronous process during the global last glacial periods, which began long before the LGM and lasted after the LGM. According to the exposure ages in the Larsemann Hills and the distance from the edge of the ice sheet, the average glacial retreat rate since MIS4 has been 71.57 m/ka. [ABSTRACT FROM AUTHOR]

We present triple oxygen isotope data from speleothems obtained by an O 2 -CO 2 Pt-catalyzed oxygen-isotope equilibration method. The high precision (9 per meg or better, 1σ SD) of our new speleothem Δ17O (carbonate 17O anomaly) data is sufficient to resolve subtle hydroclimatic signals. In addition, we determined triple oxygen isotope fractionation factors through two sets of modern paired carbonate-dripwater samples collected at a temperature of 17 ± 1 °C, which is prerequisite to the calculation of triple oxygen isotope compositions of parent meteoric waters at cave sites from speleothem proxy data. Based on this calibration, we back calculated triple oxygen isotope compositions of parent waters across well-characterized climate transitions using speleothem proxy data from three regions. Resulting oxygen-isotope data closely track the Global Meteoric Water Line (GMWL), providing a preliminary validation of the method. Our speleothem Δ17O data indicate a 21 per meg difference between Marine Isotope Stage 5d and 5e in samples from Central Asia and a 15 per meg difference between the Middle Holocene and Last Glacial Maximum in samples from the eastern Mediterranean, suggesting a shift in moisture source and/or fractionation history. Unexpectedly, there were no measurable Δ17O differences between glacial and interglacial samples from both the South American (western Amazon) and Asian (southern China) monsoon domains, implying consistent moisture-source conditions across glacial and interglacial cycles, at least in terms of relative humidity. Remarkably, Δ17O values from the western Amazonian samples are significantly higher (∼20 per meg) than those from Asian monsoon regions, suggesting lower relative humidity along moisture trajectories in the western Amazon during the Middle Holocene and Last Glacial period. Similarly, Δ17O values of the eastern Mediterranean samples are significantly higher (19–55 per meg) than those of coeval samples from Central Asia, implying different hydrological environments or moisture sources despite being in the same westerly circulation domain. Speleothem Δ17O data may thus provide new and important constraints for understanding regional and global hydroclimate dynamics. [ABSTRACT FROM AUTHOR]

Human activity and adaptation to the environmental changes on the Tibetan Plateau are under debate. Lhasa is the political and economic center of the Tibetan Autonomous Region, and was founded in 633 CE. The potential influence of changes in the landscape on the city's development remains unclear. In this paper, Optically Stimulated Luminescence and radiocarbon dating techniques were applied to determine the ages at which landforms have changed since the Last Glacial Maximum. Combining these results with archaeological evidence taken from two sites (Changguogougou and Qugong) in the Lhasa area, the relation between river migration and human adaptation was discussed. The results showed that the two terraces (T1 and T2) of the Lhasa River are fill and fill-cut terraces, and that these were formed after ∼0.9 ka and 0.08 cal ka BP, respectively. Land below an altitude of ∼3650 m above sea level was lower than the contemporary river level before ∼0.9 ka. With the down cutting of the Lhasa River, more land became available for habitation, and the flood risk to the city was also reduced. The sediments of the lower land around the Changguogou area appear to be composed of fluvial-lacustrine facies during the Last Glacial Maximum to Late Glacial period. Humans occupied the Changguogou area between ∼3.255 and 3.059 cal ka BP when there was weaker aeolian activity, and abandoned this area when aeolian activity increased. [ABSTRACT FROM AUTHOR]

Late Paleolithic sites are widely distributed in southern China (the Lingnan region), which mainly includes Guangxi, Guangdong and Hainan Provinces. Although the pebble-tool industry continued to exist in this region during the late Pleistocene and Holocene, small flake-tool assemblages also occurred and coexisted with the pebble-tool industry. The pebble-tool industries are characterized by unifacially flaked cobble tools, dominated by choppers, with a lack of handaxes. The small flake-tool industries have the characteristics of retouched tools made on small fakes, a striking platform of cores without preparation, and scrapers dominating the assemblage. Technologically and typologically, pebble tools of the Late Palaeolithic are similar to those of the Early Palaeolithic in this region and belong to the same cultural tradition. The small flake tools, however, are very different from the cobble tools. They belong to a new technology which originated from northern China during the period of the Last Glacial Maximum. The Late Palaeolithic industries in Southern China are similar to those in mainland Southeast Asia. [ABSTRACT FROM AUTHOR]

The southern limit of the Patagonian Ice Sheet at glacial maxima is poorly constrained due to a paucity of field data. This particularly applies to southern outlet glaciers of the Cordillera Darwin whose full extents have been debated by glacial geologists since 1899 CE, introducing uncertainty into estimates of total ice volume. Here we report on the stratigraphy of exposed stratigraphic sections on the west coast of Isla Hermite which include glacial diamict with discontinuous boulder pavement, overlain by successions of peats and sandy silt. The location of these sections, orientation of clasts within the glacial diamict, and geomorphology of the adjacent marine trough, suggest that an ice stream extended south from an ice centre at Cordillera Darwin across an extended Magellan outwash plain, through Paso Mantellero, to Islas Hermite and Cabo de Hornos (Cape Horn). This was similar in extent to the Canal Beagle and Lago Fagnano Ice Lobes which extended to the east. Retreat occurred sometime before 12,880 cal yr BP based on radiocarbon dated peat macrofossils immediately overlying the glacial diamict. We discuss whether this is a close minimum age, or a product of delayed onset of peat accumulation at the sampling site. • Glacial tills described on the west coast of Isla Hermite. • Confirm Paso Mantellero ice lobe extended from Cordillera Darwin to Cape Horn. • This marks the southern limit of the Patagonian Ice Sheet during the last glacial. • Maximum ice extent occurred sometime before 12,880 cal Yr BP. • Peat accumulated on Isla Hermite from 15,400 cal Yr BP. [ABSTRACT FROM AUTHOR]

The aim of this work is to build a new chronology of the Late Pleistocene glacial fluctuations in the Cantal Mountains and on the Cézallier Plateau (western Massif Central, France). The study of glacial landform-sediment assemblages is supported by the production of new exposure ages (n = 48) from (i) forty-three erratic boulders (36Cl and 10Be) spread over twelve glacial landforms, (ii) two ages from polished bedrocks (10Be) and (iii) three ages from depth profiles (10Be and 26Al) in tills. The results indicate that the majority of glacial deposits are attributed to Marine Isotopic Stage 2 (29 to 11 ka). From this dataset, four glacial stadials are discriminated: the Early-Local Last Glacial Maximum at 29–24 ka, (ii) Late-Last Glacial Maximum at 24–20 ka, (iii) a glacial still stand at approximately 17 ka, during a general deglaciation phase between 20 and 16 ka and finally (iv) a cirque stadial localized only in the Cantal Mountains at <16 ka. This new chronology strengthens the chronostratigraphy of the western Massif Central and highlights the sensitivity of the area to atmospheric circulation changes. • Revisions of glacial landform-sediment assemblages define four distinct glacial events. • Glacial fluctuations are dated to the MIS 2 with surface exposure ages using 10Be, 26Al and 36Cl (n = 48). • Two major glacier advances occurred during the Last Glacial Maximum, at 29–24 and 24–20 ka. • The paleoglacier is limited to the Cantal cirques from ~16 ka. • Paleoglacier from the western Massif Central are sensitive to north Atlantic paleoclimatic changes. [ABSTRACT FROM AUTHOR]

The continuous record offered by deep-sea sediments has been extensively used to constrain shifting continental and oceanographic conditions. Yet, past fluctuations in deep-sea benthic conditions and bottom-currents are in numerous parts of the globe scarcely documented, one such example being the South Australian margin. Indeed, though variations in surface water masses and continental aeolian dust and river outflow are well documented in the area, little is known about benthic environments and their dynamics during the last interglacial-glacial cycle. We focus here on benthic foraminiferal assemblages sampled from a sediment core recovered at 2420 m depth from a small plateau south of Kangaroo Island within the underwater Murray Canyons Group (South Australian margin). Benthic foraminiferal assemblages show a distinct separation between interglacial and glacial periods over the last 94 ka, and indicate that the benthic environment was well-ventilated and oligotrophic during glacial periods, whilst being rather marked by reduced oxygenation associated to higher food input during the Holocene and Marine Isotope Stage 5a-c. We demonstrate that autochtonous deep-sea benthic foraminiferal communities neither respond to changes in the Murray River's discharges, nor do they follow variations in aeolian dust input from South Australia. Instead, the deep-sea and the terrestrial realm appear decoupled. Moreover, our observations suggest that bottom-water slope currents were stronger during the Holocene and Marine Isotope Stage 5a-c. We propose that this strengthening was triggered by an intensification of the poleward-circulating deep eastern boundary current transporting carbon-rich Indian Deep Water. In contrast, glacial seafloor conditions, especially during the Last Glacial Maximum, may reflect a greater influence and a shoaling of oxygen-rich Antarctic Bottom Water of South Australia. This bottom-water shift would follow the northward displacement of the Subtropical and Subantarctic Fronts and coincide with a withering influence of the Leeuwin Current within surface waters. • The benthic environment was well-ventilated and oligotrophic during glacials • Reduced-oxygenation and higher nutrient input characterize warm periods • The deep-sea and the terrestrial realm appear decoupled during the last 94 ky • Interglacial foraminifera evidence a strengthening of bottom-water slope currents • Shoaling of oxygen-rich Antarctic Bottom Water may explain the glacial microfauna [ABSTRACT FROM AUTHOR]

We test the hypothesis that glacier systems, located in continental regions proximal to the Laurentide Ice Sheet (LIS), had local ice maxima considerably earlier than the LIS maximum and thus before the insolation minima at ∼21 ka. Ranges located in the northwest US exhibit earlier deglaciation timing between ∼23 and 22 ka, except for the Yellowstone region where younger time-transgressive ages complicate regional interpretations and the northern Montana ice cap where late glacial ages have recently been produced. Constraining the glacial history of more ice sheet-proximal alpine glaciers provides insight into whether the contrasting maximum-ice times in the northern Rocky Mountains were caused by regional climatic differences, such as anticyclonic wind patterns driven by the presence of the LIS. In the Pioneer Mountains of Montana, we measured in situ cosmogenic 10Be in 35 boulders on moraines marking the maximum Late Pleistocene positions of alpine glaciers from three valleys. The 10Be samples produced a range of ages, spanning pre Bull Lake to the last glaciation (i.e., Pinedale/Marine Isotope Stage (MIS) 2). We find an average exposure age for initial deglaciation of 18.2 ± 0.9 during the local Last Glacial Maximum, indicative of synchronous retreat in the Pioneer Mountains. The similarity of initial deglaciation timing of the Pioneer Mountain glaciers with the northwestern Yellowstone glacial system and northern MT ice cap suggests that topography more proximal to the LIS margin maintained full ice extent longer. Our findings, in context of previous work, suggest that in the case of the Pioneer Mountains their more proximal location to the ice margin may have delayed onset of deglaciation by greater exposure to local cooling from katabatic winds and/or additional moisture sourced from large ice-marginal glacial lakes, hence the lack of earlier deglacial ages like those found further to the west and east of the northern Rocky Mountain cordillera. [ABSTRACT FROM AUTHOR]

Distinct moraine complexes are well-preserved at the headwaters of the Requ River valley on the southern slope of Bujia Gangri, the largest center of modern glaciation in the eastern Tanggula Mountains in western China. Dating these moraines is an important step in understanding glacial history, palaeoclimate, and landscape evolution in this region. Surface exposure dating using 10Be was done on twenty-three rock samples from large granitic boulders embedded in moraine crests were collected from the Yongqu River valley and the Daxiong River valley, two glaciated valleys at the headwaters of the Requ River valley. The moraines (M W1 and M E1) closest to the current glaciers in the west (main) and east (hanging) valleys of the Yongqu River valley were dated to 203 ± 51 a (n = 4) and 162 ± 58 a (n = 3); the inner four end moraines (M W3 – 1) and outer ones (M W3 – 2) of the third moraine complex (M W3) in the main valley date to 16.8 ± 1.8 ka (n = 3) and 20.7 ± 1.3 ka (n = 2); end moraines (M E2) near the mouth of the east valley and a high lateral moraine (M EL) on its east side date to 18.9 ± 3.0 ka (n = 4); and a high lateral moraine in the Daxiong valley (M DXL) dates to 18.6 ± 1.3 ka (n = 3). The dating results indicate that these moraines were formed during the Little Ice Age (LIA), the Heinrich 1 (H1) event period, and the global Last Glacial Maximum (LGM G). These glacial events are synchronous with those across the Tibetan Plateau (TP) and its surrounding mountains. Combining the palaeoclimatic and palaeoenvironmental proxies in the TP and its surroundings, we infer that the cooling during the LIA, H1, and LGM G was a main control for these glacial advances. • A preliminary 10Be chronological framework since LGM G has been established in the eastern Tanggula Mountains. • Cooling during LIA, Heinrich 1 and LGM G glacial periods is the main determinant for palaeoglacier fluctuations. • A teleconnection between the North Atlantic cooling and palaeoglaciations since LGM G in the TP has been established. [ABSTRACT FROM AUTHOR]

• Detailed chronology revealed that Maerkang loess appeared at least ∼ 60 ka ago. • Dust flux history since MIS 3 in the TP was reconstructed. • High dust accumulation rates occurred in the Last Glacial Maximum. • Rapid climate events on the TP were linked to the North Atlantic climatic system. The Tibetan Plateau (TP) is extremely sensitive to climate change. However, climate variability during the last glaciation in the TP is not well-understood. The widely distributed loess deposits on the eastern TP serve as a significant archive for retrieving past climate changes and aeolian dust dynamics. Through detailed quartz optically stimulated luminescence and radiocarbon dating and the analysis of environmental proxies, we have established a reliable chronology of the Maerkang loess sequence in the eastern TP and reconstructed well-constrained histories of dust activities and environmental variation. Our results demonstrate that the accumulation of aeolian loess in this region occurred at least 60 thousand years ago. The dust mass accumulation rate (MAR) varied highly in the last glacial period, with high MARs in the Last Glacial Maximum and relatively low MARs in marine isotope stage (MIS) 3. Humid conditions occurred in MIS 3 (approximately 50–32 ka) due to the intensified Indian summer monsoon. The rapid climate variations of the Maerkang loess might be correlated to the Dansgaard–Oeschger cycles and the Heinrich events, which implies the significant impact of the North Atlantic climatic system on the TP. Our findings provide new evidence for a better understanding of the history of environmental variations since MIS 3 in the eastern TP. [ABSTRACT FROM AUTHOR]

In order to improve our understanding of the glacier development in central Switzerland after the Last Glacial Maximum (LGM) we have investigated moraine sequences of the Meiental ("Meien Valley"). After detailed field mapping, 34 rock samples from different moraines were dated with cosmogenic 10Be. The results indicate that the investigated moraines were deposited mainly in multi-phased advances during the Younger Dryas and the Early Holocene. This is in contrast to previous studies suggesting that these moraines represent equivalents of the older Egesen and Daun stadials. Our research shows that factors like the moraine stratigraphy, geomorphologic characteristics and Equilibrium Line Altitudes (ELAs) can be highly variable at the local scale, which can make a stadial correlation of moraines between different valleys or regions within the Alps without age constraints ambiguous and unreliable. Against this background the interregional use of ΔELAs (ELA depressions) for the parallelization of paleo-glacier extents throughout the Alps according to traditional concepts of the Lateglacial deglaciation seems to produce erroneous results. Geomorphologic observations and relative age relationships in moraine successions based on stratigraphic principles remain the basis for this kind of studies. But as we show here it is necessary to base local-to-regional comparisons of moraine sequences additionally on exposure ages to gain a more reliable understanding of the Alpine glacier development after the LGM. • Marked multi-phased glacier advances in the Meiental were dated to the YD. • Several Early Holocene moraines prove separate glacier advance/standstill phases. • YD age of supposed Daun equivalent moraines challenges the Daun as separate stadial. • The ELA approach for the parallelization of paleo glaciers has evident limitations. • Exposure dating results increasingly update the concept of the Alpine deglaciation. [ABSTRACT FROM AUTHOR]

We present a 3D reconstruction of ice thickness distribution across the New Zealand Southern Alps at the Last Glacial Maximum (LGM, c. 30–18 ka). To achieve this, we used a perfect plasticity model which could easily be applied to other regions, hereafter termed REVOLTA (Reconstruction of Volume and Topography Automation). REVOLTA is driven by a Digital Elevation Model (DEM), which was modified to best represent LGM bed topography. Specifically, we removed contemporary ice, integrated offshore bathymetry and removed contemporary lakes. A review of valley in-fill sediments, uplift and denudation was also undertaken. Down-valley ice extents were constrained to an updated geo-database of LGM ice limits, whilst the model was tuned to best-fit known vertical limits from geomorphological and geochronological dating studies. We estimate a total LGM ice volume of 6,800 km3, characterised predominantly by valley style glaciation but with an ice cap across Fiordland. With a contemporary ice volume of approximately 50 km3, this represents a loss of 99.25% since the LGM. Using the newly created ice surface, equilibrium line altitudes (ELAs) for each glacier were reconstructed, revealing an average ELA depression of approximately 950 m from present. Analysis of the spatial variation of glacier-specific ELAs and their depression relative to today shows that whilst an east-west ELA gradient existed during the LGM it was less pronounced than at present. The reduced ELA gradient is attributed to an overall weakening of westerlies, a conclusion consistent with those derived from the latest independent climate models. • LGM ice thickness reconstructed on a glacier-by-glacier basis, driven by geomorphological evidence. • During the LGM the Southern Alps contained approximately 6,800 km3 ice, of which 99.25% has subsequently been lost. • Predominant valley style of glaciation across Southern Alps but ice cap across Fiordland. • The spatial patterns of precipitation and temperature were markedly different at the LGM compared to present. • Westerly circulation was apparently reduced during the LGM when compared to present. [ABSTRACT FROM AUTHOR]

Ravine slopes at the recently discovered Nesseltalgraben site in southeastern Germany provide a unique last glacial sediment record for the Northern Calcareous Alps. The 21 m-long profile is dominated by fine-grained lacustrine-palustrine sediments overlain by several metres of glacifluvial gravels and lodgement tills of the Last Glacial Maximum and underlain by a diamicton. The age model includes 29 radiocarbon analyses and one paleomagnetic anomaly (Laschamp event) together providing a modelled age range from c. 59 to 29.6 ka cal BP, i.e. Marine Isotope Stage (MIS) 3. Apart from a description of the lithofacies, X-ray-fluorescence (XRF) scanning and elemental analyses provide high-resolution records of the geochemical composition. Multivariate analyses of XRF data separate Ca from other major elements. Carbonate contents, represented by Ca and total inorganic carbon, reach maxima in repeatedly occurring calcareous silty to sandy layers and are related to glacigenic origin. These indicate repeated inner-alpine local glaciations during stadials of MIS 3. Scanning electron microscopy and XRF data confirm the detrital origin of these layers. In contrast, organic matter and elements more resistant to chemical weathering (Si, Ti, Zr) accumulated during interstadials and concurrently elevated Rb/Sr ratios indicate intensified weathering. The high-frequency proxy variations determined for Nesseltalgraben reflect interstadial-stadial climate variability comparable with oxygen-isotope records from Greenland ice cores and Alpine speleothems. Thus, Nesseltalgraben is among the very few independently dated sediment records from continental Europe covering the entire MIS 3 and reflecting the full Dansgaard-Oeschger climate variability. • A 21 m sediment profile from the northern Alps provides a complete MIS 3 record. • Repeated inner Alpine glaciations are indicated by calcareous silt layers. • Geochemical variations reflect interstadials and stadials. • The Nesseltalgraben record resembles Dansgaard-Oeschger climate variability. [ABSTRACT FROM AUTHOR]

We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydrological cycle. During Heinrich stadials and the Younger Dryas, climatic conditions in Cuba were comparably cool and/or dry. In contrast, warm Dansgaard/Oeschger cycles were accompanied by wetter conditions. This is in agreement with previous evidence for the Holocene, when North Atlantic cold (warm) events coincided with drier (wetter) conditions in Cuba. However, our record suggests that this connection was less dominant during MIS 4 to 2, displayed by a weaker response of Cuban precipitation proxies to North Atlantic climatic shifts than during MIS 5 in particular. We hypothesize that this weaker connection was mediated by the southerly shifted ITCZ inducing a weakening of the northern branch of the Caribbean Low Level Jet which usually transports moisture into the northern Caribbean. This is strikingly evident during the deglacial, when driest and/or coolest conditions prevailed in western Cuba from HS 1 into the Younger Dryas, including the Bølling/Allerød interstadial. • We present a speleothem stable isotope and trace element record from Cuba covering the last 96 ka. • Our results confirm the link of Caribbean precipitation to NA climate, insolation and the AMOC. • Last glacial NA cold (warm) (inter)-stadials coincided with drier (wetter) conditions in Cuba. • During the LGM, our data suggest a shift to more abundant C4 vegetation and/or reduced soil activity. • We observe a weaker sensitivity to NA climate during MIS 4 to 2 compared to MIS5 and the Holocene. [ABSTRACT FROM AUTHOR]

• Abrupt mid-Holocene ice sheet thinning in western Weddell Sea Embayment since LGM. • At least 385 m of ice surface lowering revealed by in situ 14C exposure dating. • Glacial-geological data neither preclude nor mandate late Holocene ice thinning. The glacial history of the westernmost Weddell Sea sector of Antarctica since the Last Glacial Maximum is virtually unknown, and yet it has been identified as critical for improving reliability of glacio-isostatic adjustment models that are required to correct satellite-derived estimates of ice sheet mass balance. Better knowledge of the glacial history of this region is also important for validating ice sheet models that are used to predict future contribution of the Antarctic ice sheet to sea level rise. Here we present a new Holocene deglacial chronology from a site on the Lassiter Coast of the Antarctic Peninsula, which is situated in the western Weddell Sea sector. Samples from 12 erratic cobbles and 18 bedrock surfaces from a series of presently-exposed ridges were analysed for cosmogenic 10Be exposure dating, and a smaller suite of 7 bedrock samples for in situ 14C dating. The resulting 10Be ages are predominantly in the range 80–690 ka, whereas bedrock yielded much younger in situ 14C ages, in the range 6.0–7.5 ka for samples collected from 138–385 m above the modern ice surface. From these we infer that the ice sheet experienced a period of abrupt thinning over a short time interval (no more than 2700 years) in the mid-Holocene, resulting in lowering of its surface by at least 250 m. Any late Holocene change in ice sheet thickness — such as re-advance, postulated by several modelling studies — must lie below the present ice sheet surface. The substantial difference in exposure ages derived from 10Be and 14C dating for the same samples additionally implies ubiquitous 10Be inheritance acquired during ice-free periods prior to the last deglaciation, an interpretation that is consistent with our glacial-geomorphological field observations for former cold-based ice cover. The results of this study provide evidence for an episode of abrupt ice sheet surface lowering in the mid-Holocene, similar in rate, timing and magnitude to at least two other locations in Antarctica. [ABSTRACT FROM AUTHOR]

The Indo-Pacific Warm Pool is the largest source of heat and rainfall on Earth, but the mechanisms driving long-term climate variability in this region remain uncertain. Some studies suggest that precessional variations in insolation exert a primary role; alternatively, sea level change may be more important, with exposure of the Sunda and Sahul shelves leading to weakened Walker circulation across the Indian Ocean during glacial periods. The limited number of paleoclimate records from the warm pool that extend beyond the Last Glacial Maximum makes it difficult to test these competing hypotheses. Here, we present a 450,000-year long reconstruction of sea surface temperatures, sub-surface temperatures, and regional vegetation from southern Sumatra. We show that the dominant signal in each record is the 100 ky glacial cycle. We find that both surface and sub-surface temperatures cool during glacial periods, but the sub-surface cools more, reflecting a shoaling of the thermocline. Southern Sumatra and western Java consistently exhibit increased C 4 grass coverage and an enhanced dry season during glacial periods. The observed changes in the thermocline and rainfall seasonality are consistent with the shelf exposure mechanism, suggesting that sea level changes exert a prominent role in warm pool climate over glacial-interglacial timescales. • Tropical eastern Indian Ocean thermocline shoaled during last five glacial periods. • C 4 grasses expand over exposed Sunda Shelf during glacial periods. • Enhanced rainfall seasonality supports glacial drying over the Sunda Shelf. • The 100 ky glacial cycle dominates precession-driven insolation in our records. • Sea level exerts long-term control on coupled climate in the Indo-Pacific. [ABSTRACT FROM AUTHOR]

Proglacial lakes can affect the stability of mountain glaciers and can partly disengage glacier behaviour from climatic perturbations. However, their role in controlling the onset and progression of deglaciation from the Last Glacial Maximum (LGM) remains poorly understood. This lack of understanding is partly because the evidence required to consistently and robustly identify the location and evolution of ice-contact lakes is not standardised. In this paper we therefore firstly present a new set of criteria for identifying the landform and sedimentary evidence that defines and characterises ice-marginal lakes. Secondly, we then apply these key criteria with the aid of high-resolution topographic mapping to produce the first holistic definition and assessment of major proglacial lake landforms and sediments pertaining to the end of the LGM across South Island, New Zealand. The major findings of this assessment can be grouped to include that: (i) The localised constraints to proglacial lake extent were topography, glacier size and meltwater/sediment fluxes, (ii) Lake damming was initiated by outwash fan-heads that interrupted water and sediment flows down-valley, and (iii) New Zealand LGM lakes were unequivocally in contact with a calving ice margin. These findings will be useful for reconstructing ice dynamics and landscape evolution in this region. • Key criteria to identify, characterise and interpret landforms and sediments associated with ice-contact proglacial lakes. • Exploitation of high-resolution LiDAR topographic data for proglacial lakes across South Island, New Zealand. • Synthesis analysis of the 3D geometry, landforms and sediments, and interpretation of the evolution of New Zealand LGM lakes. [ABSTRACT FROM AUTHOR]

Here we summarize the motivation and issues surrounding the responses of ice sheets and sea level to past climate warming as part of the PALeo constraints on SEA level rise (PALSEA) working group. Papers in this special issue of Quaternary Science Reviews focus on the timescale of glaciations during the late Pliocene, the magnitude of ice-sheet fluctuations and volume leading up to and during the last glacial maximum, the timing and persistence of ice-sheet impacts on deglacial and future relative sea-level change, and relative sea-level change during peak interglacial climate. A more dynamic cryosphere is noted under both late Pliocene and last glacial cycle climate conditions, while relative sea-level changes during the last deglaciation appear to correspond closely with individual ice-sheet deglaciation. Lastly, relative sea-level change during peak interglacial conditions may have fluctuated by as much as a meter, although the sources of such variability (Greenland, Antarctica or elsewhere) remain elusive. [ABSTRACT FROM AUTHOR]

Calculating cosmogenic-nuclide surface-exposure ages is critically dependent on a knowledge of the altitude of the sample site. Changes in altitude have occurred through time as a result of glacial isostatic adjustment (GIA), potentially altering local nuclide production rates and, therefore, surface-exposure ages. Here we assess the impact of GIA on surface-exposure dating by calculating global time-dependent production rates since the Last Glacial Maximum using surface elevations that were corrected and uncorrected for GIA. We find that the magnitude of the GIA effect is spatially and temporally variable. Nuclide production could be reduced by up to 50% in the interior of large ice masses (in North America, Scandinavia and West Antarctica) at times of maximum glacial isostatic depression. Although smaller, the effect is still significant at ice sheet margins, where nuclide production is reduced by >5% and potentially >10%, making exposure ages older in those areas. Away from the ice sheet margins, land surfaces can be isostatically elevated, which can increase nuclide production by >5% and, therefore, make exposure ages younger. Areas that were more recently exposed or that are distal to large ice masses will generally be less affected. Importantly, we find that the effect at the primary 10Be production calibration sites is <1%. Applying a GIA correction to surface-exposure data may help resolve mismatches between some chronologies, but not necessarily in all regions, implying that additional factors may need to be considered. Past atmospheric changes can amplify or reduce the impact of GIA on nuclide production, and the combined effects should be fully accounted for in the future. These time-dependent influences on surface-exposure dating have potentially important implications for interpreting chronologies and for using the data to constrain ice sheet models. • Glacial isostatic adjustment (GIA) can make exposure age estimates older or younger. • Nuclide production can be reduced by up to 50% from isostatic depression. • The GIA effect at the primary 10Be production rate calibration sites is negligible. • Correcting existing exposure datasets can make ages up to ∼2,500 years (15%) older. • Atmospheric changes may amplify or reduce the impact of GIA on exposure ages. [ABSTRACT FROM AUTHOR]

The only glaciers existing today in the Iberian Peninsula are small features located in the Pyrenees, though their number and extension has undergone significant changes over the Late Quaternary. The wide range of glacial landforms and deposits distributed across different Iberian ranges suggests the occurrence of several past periods with larger glacial systems. The objective of this research is to summarize the current knowledge on the spatial and temporal patterns of glacial activity in the Iberian mountains during the Late Quaternary. To this purpose, the chronological framework was divided in six periods: glaciations prior to the Last Glacial Cycle (Middle Pleistocene), Last Glacial Cycle (Late Pleistocene), Termination-1, Holocene, Little Ice Age (LIA) and present-day. The data were geographically divided considering the mountain systems where glacial evidence exists: Pyrenees, Cantabrian Range, NW ranges, Central Range, Iberian Range and Sierra Nevada. During Quaternary cold stages, ice accumulated in the head valleys of these mountain ranges and glaciers flowed down-valleys. In all cases, glaciers remained confined within the mountain systems and did not reach the surrounding lowlands. Depending on the combination of temperatures and moisture conditions, more or less ice was stored. In some ranges, there is evidence of Middle Pleistocene glaciations, one potentially correlating with marine isotope stage (MIS) 12 and another correlating with MIS 6 with glaciation dated to ca. 130-170 ka. However, most of the glacial records correspond to the Last Glacial Cycle and subsequent Termination. The maximum glacial expansion of this last Pleistocene glaciation stage occurred well before the global Last Glacial Maximum (LGM) between 30 and 60 ka in the Cantabrian Mountains and Pyrenees, at ca. 30 ka in Sierra Nevada and NW ranges, and (almost) synchronously to the LGM in the Central Range and Iberian Range. A massive glacial retreat occurred in all ranges at 19-20 ka, but the long-term deglaciation process was interrupted by cold intervals, such as the Oldest and Younger Dryas, which favoured glacial expansion in the highest mountains. Temperature increase recorded during the Holocene conditioned the melting of glaciers, which only reappeared in the highest massifs during the coldest periods, such as the LIA. However, post-LIA warming led to glacier disappearance in the Cantabrian Mountains, Sierra Nevada and most massifs of the Pyrenees, together with an accelerated shrinkage of the small glaciers still existing in this range at elevations near 3000 m. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First glacial and de-glacial chronology from the Sikkim higher Himalaya. • Glaciation dates back to the MIS 2 and started at ∼28 ± 2.8 ka. • We ascribe the glaciation to lower temperature and increase moisture. Abstract The present study investigates the relics of the most extensive glacier advances and their retreat in the transitional climatic zone of the Chopta valley, northern Sikkim Himalaya with an aim to understand the forcing factors. The optically stimulated luminescence (OSL) dating of the stratigraphically oldest glacier advance and its retreat in the Chopta valley revealed that the glacier advanced at ∼28 ± 2.8 ka and sustained through the global Last Glacial Maximum (gLGM; 26.5 ka and 19 ka; Mix et al., 2001). The deglaciation is manifested by recessional moraine (ridge) dated at ∼18 ± 2.2 ka. Comparing the results of the present study with the existing glacial chronologies from the Himalayan region, it has been observed that irrespective of the geographical locations; the intensified mid latitude-westerlies during the gLGM and the associated decrease in winter temperature was the major driver of glacier advance during the MIS-2. [ABSTRACT FROM AUTHOR]

Abstract Recent advances in palaeoecology provide growing evidence of complex spatio-temporal patterns of tree species survival during the last glaciation. The distribution of Sweet chestnut (Castanea sativa Mill.) glacial refugia is still controversial. For this study we built an updated database containing almost all palaeobotanical data on Castanea published to date in the scientific literature and/or stored in the European and African pollen databases (EPD and APD). We used the collected data for assessing the sweet chestnut refugia during the Last Glacial Maximum (LGM). Furthermore, we identify the main changes in the distribution range of the species during the last 200 ka all over Europe. Confirmed chestnut refugia are the Transcausasia, where the species played a prominent role in the forest vegetation, and the Italian and Iberian Peninsulas, where it was restricted to scattered pockets providing favorable habitats. The species may have also survived in the Marmara region and in the Levant, while for the South-Eastern Balkans, north and central France and Northern Africa, the available evidence is too scarce yet for inferring local survival. Mountain ranges and seawater masses played a crucial role in determining the species survival during cold stages. Almost four fifths (79%) of the palaeobotanical sites with pre-cultivation Castanea records were found in the scientific literature, while the remaining 21% was extracted from the EPD and APD. Our study thus shows the growing importance of such curated databases as a key resource for palaeoecological synthesis products, emphasises the relevance of gaining a better spatio-temporal coverage by an extensive review of scientific literature, and underscores the urgent need of gaining new state-of-the art multiproxy records for assessing the causes and consequences of species survival under strongly varying climatic conditions. Highlights • Data are retrieved from the literature (79%) and the European Pollen Database (21%). • There are 856 european palaeobotanical sites with Castanea in pre-cultivation samples. • Transcaucasia, Italy, Iberia, Marmara region and Levant are the five confirmed refugia. • Proximity to mountains and seas was crucial for the survival of the species. • During the early-middle Holocene the species spread naturally from the refugia. [ABSTRACT FROM AUTHOR]

Abstract Proxy data from pollen and mollusc indicator species, periglacial phenomena, changes in geometry of mountain palaeoglaciers and based on selected lithological and geomorphological features enabled reconstruction of the Late Pleistocene climate characteristics in Poland and adjacent areas. Climate during the Eemian was generally stable but with a distinct west-east gradient in summer. Strong influence of the Atlantic air masses moving to the east resulted in the annual precipitation over 600 mm. Climate instability in the late Eemian as well as during stadials and interstadials of the Early Weichselian was expressed by progressive cooling and increasing temperature difference between winters and summers, reflecting stronger continentalism towards the west, accompanied by decreased precipitation. Periglacial frost crackings and polygonal patterns indicated occurrence of permafrost in Poland already at about 49 ka BP and its occurrence until the termination of the last glaciation. These periglacial structures have developed at mean annual temperatures from −9 to −4 °C, with winter extremes up to about −25 °C. Mean summer temperature reached likely around 10 °C as suggested by palaeobotanic record. Palaeoglaciological studies of mountain glaciers across Europe allowed inferring their activity and sensitivity to climatic fluctuations during the Late Weichselian. The Weichselian of central Europe was controlled mostly by the southerly and easterly circulation dominated by climate cyclones and anticyclones, respectively. An inflow of air masses from the west was significantly limited and concentrated mainly within the so-called periglacial corridor between the Scandinavian ice sheet and the Alps. Such circulation pattern determined serious reduction of precipitation during the Last Glacial Maximum that reached 60% in relation to modern conditions. The following Late Pleistocene cold phases (Oldest and Younger Dryas) were slightly warmer and wetter with increasing contribution of the westerlies that were strongly dependent on progressing shrinkage of the Northern Hemisphere ice sheets. [ABSTRACT FROM AUTHOR]

Abstract Constraining glacial history and process on Mt Mansfield, the highest peak in Vermont (1339 m a.s.l.), provides insight into how the Laurentide Ice Sheet shaped the underlying landscape, when latest Pleistocene ice retreated, and how upland and lowland glacial histories relate. Here, we quantify in situ cosmogenic 10Be in 20 bedrock and boulder surfaces, as well as in situ cosmogenic 14C in three of those surfaces, to assess subglacial erosion and exposure history. Isotopic concentrations indicate that Mt. Mansfield's lower elevations (∼400–1200 m a.s.l.) were deeply eroded by at least several meters during the last glaciation and then deglaciated rapidly; 10Be ages across this elevation span are indistinguishable and average 13.9 ± 0.6 ka (n = 15), suggesting that 800 m of ice thinning occurred within at most about a millennium. Conversely, the higher elevations (>1200 m a.s.l.) preserve a more complex geomorphic history. Mt. Mansfield's summit surfaces contain 10Be from previous periods of exposure, indicating that the mountaintop landscapes were likely preserved beneath cold-based, weakly-erosive glacial ice. Exposure ages from the shorter-lived isotope, 14C, are younger (9.7 and 11.7 ka), suggesting that Mt. Mansfield's summit was covered until the early Holocene, perhaps by snowfields, ice carapaces, and/or till. Our findings, in context of previous work, suggest that thinning Laurentide ice flowed through the valleys for at most hundreds of years following deglaciation of the uplands, but that the summit remained shielded by ice or sediment for millennia after the valleys became ice-free. Highlights • We use cosmogenic nuclides to constrain Laurentide Ice Sheet history and behavior. • Mt. Mansfield, the highest point in Vermont, was deglaciated rapidly ∼13.9 ka. • The lower elevations (<1200 m a.s.l.) were deeply eroded by flowing ice. • The summit area was covered by cold-based ice and was minimally eroded. [ABSTRACT FROM AUTHOR]

Abstract Ocean net primary productivity (Npp) is a key component of the marine carbon cycle. Multi-model Npp projections based on a few decades of satellite data show large uncertainties, in particular at low latitudes (30°N−30°S). Calibration of sedimentary proxies with satellite-based Npp estimates allows for the quantitative reconstruction of this variable at longer time-scales. Relative abundance of deep-photic zone coccolithophore species Florisphaera profunda in the fossil record can potentially be used as a quantitative proxy for Npp. However, the robustness of this proxy calibration has been tested in very specific oceanographic settings using surface sediment samples. Here, we use a global dataset of surface sediment (n = 1258) and sediment trap (n = 26) samples with relative abundance data of F. profunda (%) to test the robustness of this proxy as a quantitative indicator of Npp. We study the modern and paleo-ecology of this species and the main factors affecting its latitudinal distribution. Results show that F. profunda % is a strong indicator of Npp at latitudes between 30°N and 30°S, while at higher latitudes temperature-related variables are more important. We develop a global calibration model between satellite Npp estimates and F. profunda for the latitudinal range between 30°N and 30°S, and we apply it to several low-latitude sediment cores with available F. profunda counts covering the Late Glacial Maximum (LGM; 24–19 ka) and the Mid-to-Late Holocene period (MLH; <6 ka). Reconstructed Npp during the LGM is 15% higher than during the MLHdue to the intensification of trade winds that enhanced oceanic upwelling at low latitudes. Highlights • An extensive new modern and fossil global dataset of Florisphaera profunda relative abundances. • F. profunda % show strong correlation to net primary productivity (Npp) only at low latitudes. • Temperature control of F. profunda at high latitudes does not warrant its use as Npp indicator. • F. profunda -Npp calibration allows quantitative reconstruction of past ocean productivity. • Reconstructed Npp at low latitudes is 15% higher during the LGM than the MLH. [ABSTRACT FROM AUTHOR]

Abstract Subglacial hydrology modulates how ice sheets flow, respond to climate, and deliver meltwater, sediment and nutrients to proglacial and marine environments. Here, we investigate the development of subglacial lakes and drainage networks beneath the Fennoscandian and Barents Sea ice sheets over the Late Weichselian. Utilizing an established coupled climate/ice flow model, we calculate high-resolution, spatio-temporal changes in subglacial hydraulic potential from ice sheet build-up (∼37 ka BP) to complete deglaciation (∼10 ka BP). Our analysis predicts up to 3500 potential subglacial lakes, the largest of which was 658 km2, and over 70% of which had surface areas <10 km2, comparable with subglacial lake-size distributions beneath the Antarctic Ice Sheet. Asynchronous evolution of the Fennoscandian Ice Sheet into the flatter relief of northeast Europe affected patterns of subglacial drainage, with up to 100 km3 more water impounded within subglacial lakes during ice build-up compared to retreat. Furthermore, we observe frequent fill/drain cycles within clusters of subglacial lakes at the onset zones and margins of ice streams that would have affected their dynamics. Our results resonate with mapping of large subglacial channel networks indicative of high-discharge meltwater drainage through the Gulf of Bothnia and central Barents Sea. By tracking the migration of meltwater drainage outlets during deglaciation, we constrain locations most susceptible to focussed discharge, including the western continental shelf-break where subglacial sediment delivery led to the development of major trough-mouth fans. Maps of hydraulic potential minima that persist throughout the Late Weichselian reveal potential sites for preserved subglacial lake sediments, thereby defining useful targets for further field-investigation. Highlights • We present modelled subglacial water storage and drainage between 37–10 ka BP. • Up to 3500 potential subglacial lakes predicted during LGM, storing >460 km3 of water. • Subglacial lake clusters are predicted with potential for fill/drain cycles and flood events. • Persistent lakes over the glaciation define potential sites for preserved sediments. • Catchment evolution and drainage outlet migration reveals subglacial discharge foci. [ABSTRACT FROM AUTHOR]

Abstract The relatively warm climate conditions prevailing today in the Mediterranean region limit cold geomorphological processes only to the highest mountain environments. However, climate variability during the Late Pleistocene and Holocene has led to significant spatio-temporal variations of the glacial and periglacial domain in these mountains, including permafrost conditions. Here, we examine the distribution and evolution of permafrost in the Mediterranean region considering five time periods: Last Glaciation, deglaciation, Holocene, Little Ice Age (LIA) and present-day. The distribution of inactive permafrost-derived features as well as sedimentary records indicates that the elevation limit of permafrost during the Last Glaciation was between 1000 m and even 2000 m lower than present. Permafrost was also widespread in non-glaciated slopes above the snowline forming rock glaciers and block streams, as well as meter-sized stone circles in relatively flat summit areas. As in most of the Northern Hemisphere, the onset of deglaciation in the Mediterranean region started around 19-20 ka. The ice-free terrain left by retreating glaciers was subject to paraglacial activity and intense periglacial processes under permafrost conditions. Many rock glaciers, protalus lobes and block streams formed in these recently deglaciated environments, though most of them became gradually inactive as temperatures kept rising, especially those at lower altitudes. Following the Younger Dryas glacial advance, the Early Holocene saw the last massive deglaciation in Mediterranean mountains accompanied by a progressive shift of permafrost conditions to higher elevations. It is unlikely that air temperatures recorded in Mediterranean mountains during the Holocene favoured the existence of widespread permafrost regimes, with the only exception of the highest massifs exceeding 2500-3000 m. LIA colder climate promoted a minor glacial advance and the spatial expansion of permafrost, with the development of new protalus lobes and rock glaciers in the highest massifs. Finally, post-LIA warming has led to glacial retreat/disappearance, enhanced paraglacial activity, shift of periglacial processes to higher elevations, degradation of alpine permafrost along with geoecological changes. [ABSTRACT FROM AUTHOR]

Abstract During the Local Last Glacial Maximum (LLGM), the Northern Apennines hosted more than 100 valley and mountain glaciers covering collectively more than 260 km2. Cosmogenic 10Be exposure ages obtained for the first time along the Apenninic range constrain the age of the LLGM to pre-date ca 21 ka. The estimated volumes of these Late Pleistocene glaciers exceeded 9.1 km3 w.e. Their reconstructed Equilibrium Line Altitudes (ELAs) range from ca. 1200 m a.s.l. for northerly facing compound basin valley glaciers to ca. 1620 m a.s.l. for southerly facing mountain glaciers. Reconstructed ELAs in the western sector of the Northern Apennines were among the lowest recorded for the whole of the Italian peninsula, including the Alps, and also when compared with other mountain chains in the surrounding Mediterranean basin. These probably reflect exceptionally high accumulation rates fed by storm tracks in the western Mediterranean, which in turn has implications for the atmospheric circulation pattern that prevailed in the region at the time. [ABSTRACT FROM AUTHOR]

The study reports new progress in the glacial chronology from new sites of the Chandrabhaga basin (CBB), in the transition between the monsoon-dominated Pir-Panjal and westerly-dominated Trans-Himalaya, in Lahaul Himalaya, northern India. In Lahaul, asynchronous timing and extent of late Quaternary glaciation have been reported (Owen et al., 1996, 1997, 2001; Eugster et al., 2016). The established oldest and most extensive Chandra glacial stage remains undated and speculative. We reconstrain the late Quaternary glacial history of the CBB using geomorphological mapping, Infrared Stimulated Luminescence (IRSL), and 10Be Terrestrial Cosmogenic Nuclide (TCN) surface exposure dating. Four local glacial stages, the Chandra, Batal, Dali, and Mayar, are dated to 152 ± 37 ka, 43 ± 3 ka, 21 ± 2 ka, and Little Ice Age (LIA), respectively. The Chandra glacial stage occurred during the late Marine Isotope Stage 6 (MIS 6; 186 ± 30 – 113 ± 10 ka), characterized by thick lacustrine deposits, rock benches, and ice-polished bedrock along the trunk valleys. We provide the first account of the numerical dating for the much-awaited timing of the oldest Chandra glacial stage (Local Last Glacial Maxima; LLGM) in the region (Owen et al., 1996, 1997, 2001). The LLGM in the CBB is much older than previously thought, consistent with some north-western Himalayan glacial records (Owen et al., 2006; Dortch et al., 2010; Hedrick et al., 2011; Orr et al., 2017, 2018). The Batal glacial stage occurred during the early MIS 3 and is dated from 47 ± 2 to 41 ± 2 ka, represented by the thick lacustrine deposits and impressive terraces. The Dali glacial stage occurred during the Global Last Glacial Maxima (GLGM), characterized by a series of latero-frontal recession moraines, and is dated from 33 ± 3 to 13 ± 1 ka. The Mayar advance is characterized by confined tributary valley glaciers, possibly linked to the LIA advance reported in the Kulti valley (Saha et al., 2019). The equilibrium line altitude (ELA) rose by ∼486 m from the Chandra stage to the present day. Reconstructed ELA altitudes and glacial landforms demonstrate that the glaciations have become progressively less extensive through time for this part of the western Himalayas. The change of glaciation pattern during the later part of the Quaternary is like other regions of the orogen, such pattern of glaciation reflects regional climatic forcing. • We present novel 31 k-feldspar IRSL and 12 cosmogenic 10Be ages for Chandrabhaga basin, Lahaul Himalaya, northern India. • We reconstrain the chronology for previously reported glacial stages of Owen et al. (1996, 1997, 2001). • We assign previously reported but undated oldest Chandra glacial stage with absolute dates. • Findings suggest that the Local Last Glacial Maxima in this region is much older than previously thought. • Our findings strongly question the previously reported extensions and rate of deglaciation during Global Last Glacial Maxima by Eugster et al. (2016). • Each glaciation becomes progressively less extensive in the Chandrabhaga basin over time. [ABSTRACT FROM AUTHOR]

Substantial stratigraphic evidence from the Late Quaternary at orbital- and millennial‒scales indicates that the formation and evolution of aeolian‒sand landscapes results from the interaction between regional aeolian and fluvial‒lacustrine activity. In many deserts (sandy lands) across the planet, fluvial‒aeolian interplay at the glacial‒interglacial scale since the Late Quaternary has been responsive to monsoonal precipitation, and linked to atmospheric CO 2 and periodic variations in insolation. However, the patterns of fluvial‒aeolian interplay and their relationship with climate change are not always consistent over a given timescale during the Late Pleistocene. The paucity of studies on fluvial‒aeolian interplay in the Mu Us Desert (MUD) during the Last Glacial Period (LGP) hinders our understanding of the relationships between the dynamics of aeolian and fluvial‒lacustrine landscapes and their drivers. Here, based on a comprehensive field survey and stratigraphic dating of a typical fluvial‒aeolian sequence in the MUD, we synthesized the chronology of fluvial‒lacustrine and aeolian strata during the LGP. Our results show that extensive development of a fluvial‒lacustrine environment in the MUD during the LG mainly occurred during the late Last Glacial Maximum (LGMa, 20.1–18.4 ka BP) and Bølling/Allerød interstadial (14.8–12.6 ka BP), while thicker aeolian sands extensively accumulated during the Heinrich Stadial 2, Heinrich Stadial 1, and Younger Dryas periods. However, the development of fluvial‒lacustrine environments showed considerable spatial heterogeneity, mainly occurring on the southern and eastern margins of the desert, while they were extremely rare in the central and western parts of the desert owing to strong wind erosion. Comparisons with other high-resolution geological records from the Asian monsoon region reveal that the fluvial‒aeolian interplay in the MUD during the LGP was highly consistent with the evolution pattern of the East Asian summer monsoon (EASM) on the millennial‒centennial scale, and indicate that the development of fluvial‒lacustrine environments was mainly controlled by an increase in monsoonal precipitation during strengthening of the EASM. Consistency with other broad changes at high latitudes in the Northern Hemisphere suggests that fluvial‒aeolian interplay during the LGP in northern Chinese deserts, as represented by the MUD, was mainly controlled by changes in high-northern-latitude ice volume and the Atlantic Meridional Overturning Circulation. • Fluvial‒aeolian interplay during the Last Glacial Period in the Mu Us Desert is studied. • Regional fluvial‒aeolian interplay during the LGP is correlated with millennial-scale global climatic events. • Regional fluvial‒lacustrine environments mainly developed during the LGMa and B/A. • Fluvial‒lacustrine and aeolian processes during the LGP were mutually reinforcing and inhibiting. • High-northern-latitude forcing modulated millennial-scale fluvial‒aeolian interplay in the MUD during the LGP. [ABSTRACT FROM AUTHOR]

The area of Prados del Cervunal (PC) is an intra-morainic topographic depression located at 1800 m asl in the divide or interfluve between Garganta de Gredos and Garganta del Pinar valleys (Central Gredos; Iberian Central System, ICS). Both valleys, along with the adjacent Hoya Nevada, were occupied by glaciers during the Upper Pleistocene, leading to the development of the Prados del Cervunal moraine complexes studied in this work. Using cartographic methods and morphostratigraphic analysis, the three main glacial formations established in the Regional Chrono-Evolutionary Pattern for the ICS, Peripheral Deposits (PD), Principal Moraine (PM) and Internal Deposits (ID), have been identified and mapped in this area. The chronology of these formations has been implemented by Cosmic Ray Exposure (CRE) techniques using 10Be (new data) and 26Cl (previous data, recalculated in this work) in samples from morainic boulders. With these data, the following chrono-evolutionary sequence has been established: (stage 1) local-Maximum Ice Extent (MIE), dated in 25.0 ± 1.4 ka and corresponding to the maximum age obtained in these paleoglaciers; (stage 2) period of oscillations around the MIE, corresponding to the development of the PD Formation between ∼25 ka and ∼21 ka; (stage 3) period of readvance and stabilisation, dated after ∼21 ka (average age obtained for the PD moraines attached to PM moraines) and previous to ∼18 (minimum age obtained for a main crest of the PM formation); and (stage 4) onset of deglaciation dated around to ∼18 ka (average of ages obtained for the first main crest of the ID formation). During the stages of maximum ice expansion, these three glaciers formed an Ice field whose tongues were interconnected on the PC flat by an ice transfluence system (stages 1 and 2, Plateau Glacier Period). In later stages, the ice masses were partitioned, giving rise to valley glaciers and large moraines forming morainic complexes like those of PC (stages 2, 3 and 4, Valley Glaciers Period). The local MIE and onset of deglaciation stages in this area show a good fit with the ages stablished to global level for the global Last Glacial Maximum (LGM) and the onset of the Last Glacial Termination (Termination I). They also show good correlation at local (with other areas of the ICS), peninsular (with other Iberian mountains) and continental (some areas of the Alps and mountains of Central Europe) level. Finally, this evolutionary sequence and its correlations allowed us to adjust and validate some units of the Regional Chrono-Evolutionary Pattern model and propose the Gredos-Pinar-Cabeza Nevada glacial system as benchmark for the glaciation of Marine Isotope Stage (MIS) 2 in the Iberian Peninsula. • Glacial Geomorphology in Gredos-Pinar-Hoya Nevada paleoglaciers (Sierra de Gredos) was established. • New chronological data using 10Be-CRE and previous data using 36Cl-CRE allowed precise dating of the morainic sequence. • Previous morphology, aspect and debris supply as control factors of the layout and the dynamic of ice masses. • The local-MIE and the subsequent major readvance stage occurred within the LGM period. • Model from MIS 2 glaciation in the area: MIE and readvance post-MIE intra-LGM immediately followed by Termination-I. [ABSTRACT FROM AUTHOR]

Greenland ice cores are high-resolution archives of atmospheric dust loadings, and a better understanding of the driving factors for Greenland ice core dust concentration changes across different timescales provides valuable insights into changes in atmospheric circulation pattern and benefits accurate prediction of the future climate change. In this review, based on the dust record of the NGRIP ice core, we systematically characterize the Greenland ice core dust concentration changes during the last glacial, and explore the major driving factors. Based on the previously published and own isotope geochemical data, we estimated the contributions of provenances for the Greenland ice core dust using Bayesian mixing model. The results show that the dust was primarily derived from the Asian sources (71.5%) during the last glacial. Dust contributions from Africa include 10% (6.9%–12.0%) for North Africa and 6.9% (4.6%–8.3%) for West Africa; East Central & Eastern European sources yield a contribution of 11.7% (8.3%–14.2%). Subsequently, we revealed the contributions of multiple influencing factors to the Greenland dust concentration changes on orbital scale using the Lindeman-Merenda-Gold method. Overall, the findings highlight a crucial role of the aeolian activity in sources in controlling the Greenland dust concentration changes during the last glacial (63%). A greater effect of the atmospheric transport efficiency is also found (31%); by contrast, the spilt of jet stream contributes little (5%). We further argue that the variations in contribution of intensity of aeolian activity in sources through MIS2–5 may be related to glacial grinding by high-altitude mountain glaciers, with more significant influences exerted on variations in the Greenland dust concentration during MIS4. Inversely, more contributions from the atmospheric transport efficiency (wet deposition and reduced atmospheric residence time of dust in transport pathways) are observed during MIS2 and MIS3 than those during MIS4 and maybe MIS5. The results about changes of the contributing proportions of intensities of the different source areas throughout MIS2–5 reveal the major roles of sediment availability, displacement of the westerlies, and the Northern Hemisphere ice volume. The variations in contribution of the split of jet stream through MIS2–5 also demonstrate its minor role in influencing the Greenland dust concentration changes. In addition, it is suggested that the 21-ka precessional period found in the Greenland dust records possibly reflects the integrated response of paleoclimate changes to Milankovitch forcing (northern summer insolation). As for variations in the last glacial maximum (LGM) dust concentration, the enhanced dust emissions induced by changes of the North Atlantic jet stream over the Central and Eastern Europe and the Tarim Basin promoted the sharp dust concentration increases during the early-LGM. Such a scenario was intimately related to more frequent Rossby-wave breakings under negative NAO/AO phases. Furthermore, loss of dust aerosol due to wet deposition en route and ice accumulation rates could also have affected the Greenland dust concentration changes during the LGM. The findings are thought to enable interpretation of the observed decoupled relationship between the CLP loess accumulation rates and the Greenland dust concentrations during the LGM. • Systematically characterizing the Greenland ice core dust flux changes. • Provenances of the Greenland ice core dust were identified in detail. • Drivers of the last glacial dust content changes were quantitatively assessed. • Providing a full explanation of the sharply changing dust contents during the LGM. [ABSTRACT FROM AUTHOR]

The NE Tibetan Plateau (NETP) is one of the most ecologically vulnerable areas, with large expansion and retreat of desert area since the Last Glacial Maximum. However, the long-term history of desertification in this area and its mechanisms are still unknown due to lack of long-term and well-dated records. Here we present the results of sand particle content (a proxy of local materials) and detrital-zircon ages from a high-resolved loess-paleosol section spanning the past 420 ka in the Menyuan (MY) Basin lying in the NETP. Our results show that the provenance of loess units (formed in glacial periods) was strongly influenced by local desertified materials that were mainly produced by alpine glaciers surrounding the basin, which was significantly different from the paleosol units (formed in interglacial periods). The strong signals of ∼100 kyr and ∼ 20 kyr cycles in the content of local materials suggest that the desertification of the MY Basin was controlled by both the late Quaternary ∼100-kyr ice age and the ∼20-kyr precession cycles, which is obviously different from the periodicities of the classic Luochuan loess section in the mainland of the Chinese Loess Plateau (CLP). The strong ∼20-kyr cycle in the MY Basin suggest that the alpine glaciation activities in the NETP were driven by local summer insolation. These results allow us to characterize the long-term natural variability of desertification in the NETP, as well as the mechanisms for the spatial and glacial-interglacial variations of loess provenance on the CLP. • The provenance of MY loess varied over glacial-interglacial cycles. • Periodic desertification of the NETP was driven by orbital cycles. • Alpine glaciation activities in the NETP were driven by local summer insolation. • NETP is an important dust source for loess on the CLP during glacial periods. [ABSTRACT FROM AUTHOR]