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The marine isotope stage (MIS) 5a to 4 transition (∼74 ka) was associated with rapid ice sheet expansion, declining moisture availability globally, and significant upheaval of terrestrial ecosystems across the northern hemisphere. Here, we present precisely dated speleothem trace element records spanning ∼90 to 70 ka from Dim Cave (Southern Türkiye) which provide crucial information regarding the climate response to this transition from the Eastern Mediterranean region. Trace element variability recorded in stalagmite DIM-E3 captures shifts in detrital influx, bedrock dissolution, and soil activity that collectively record two climatic signals: (1) high regional moisture availability between MIS 5c and 5b, and (2) increasingly arid conditions across the MIS 5a to MIS 4 transition. Both are contemporaneous with evidence for severe drying recorded across the Eastern Mediterranean and Middle East, as well as Asia, Europe, South America, and the North Atlantic. These results shed new light on the environmental consequences of rapid change in a climatologically sensitive region, and underscore the significance of atmospheric teleconnections in propagation of abrupt climate variability during the last glacial period. • The MIS 5-to-4 transition (∼74 ka) requires closer study in the Eastern Mediterranean. • We present precisely dated speleothem trace element records spanning ∼90 to 70 ka from Dim Cave (S. Türkiye). • Speleothem DIM-E3 records distinct changes in detrital influx, bedrock dissolution, and soil activity. • An abrupt shift to aridity is observed across the MIS 5a to MIS 4 transition. • Results underscore the consequences of rapid climate change in this hydroclimatically-sensitive region. [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]

Spatial differences of rainfall in monsoonal China during the last glacial period remain contentious. Here, we present new 230Th-dated stalagmite records (δ13C and δ18O) from central China (the Yangtze River valley), spanning approximately 75–10 ka BP, to address this issue. We interpret the stalagmite δ13C variations primarily as indicators of regional rainfall changes, which show significantly decreased rainfall during MIS 4 and late MIS 3 to MIS 2. On the millennial timescale, the δ13C record indicates decreased rainfall during Heinrich (H) events and increased rainfall during Dansgaard-Oeschger interstadials. The strong correlations between our δ13C record and the westerly proxies suggest that the westerly jet played a crucial role in influencing rainfall patterns in monsoonal China throughout the last glacial period. We propose that rainfall changes in central China were consistent with northern China on both orbital and millennial timescales during the last glacial period. This observation contrasts with the modern rainfall differences between northern and central China. Our results imply that with a colder climate in high northern latitudes, the rain belt over monsoonal China influenced by the westerly jet shifted further south beyond the Yangtze River Valley during MIS 4, late MIS 3 to MIS 2 and H events, leading to a consistent decrease in rainfall over central and northern China. In contrast to the rainfall records, the stalagmite δ18O values were more negative during late MIS 3. The δ18O variations on the orbital timescale are likely related to the changes in the tropical ocean conditions controlled by insolation, which determines the δ18O values in evaporated moisture before its transport into the Asian continent. On the millennial timescale, our δ13C and δ18O records exhibit coupled variations, implying that the stalagmite δ18O variations are consistent with the rainfall changes in central and northern China. • New stalagmite δ13C and δ18O records spanning the last glacial period (75–10 ka BP) from central China. • Consistent rainfall changes in central and northern China on both orbital and millennial timescales. • Coupled variations between δ13C and δ18O records on the millennial timescale. [ABSTRACT FROM AUTHOR]

Aeolian activity on the Tibetan Plateau (TP) has profound effect on the Asian and global climate. In the southern TP, loess deposition widely occurred associated with the massive glaciers and large rivers, recording the interplay history among the aeolian activity, atmosphere, and cryosphere. However, the initiation age of the loess and the factor controlling the loess formation are still controversial. Here, three drilling cores were retrieved from Linzhi area, in the eastern Yarlung Zangbo River Basin of the southern TP, which reached the bedrock and documented the loess development in the southern TP. Based on the optically stimulated luminescence, electron spin resonance, paleomagnetism dating and relative paleointensity correlation, the basal age of the drilling core was constrained at 584 ka revealing the onset of significant aeolian activity on the southern TP. Synthesize this study and previous work on the loess age across the TP, three stages were identified, namely 3600, 2800–2700, and 1200–600 ka, with the age trending younger from north to south. Extensive loess development on the TP occurred between 1200 and 600 ka, which was mainly ascribed to the global cooling during the mid-Pleistocene Transition. During this time, the ampler glaciers extent significantly expanded, westerly displaced southward and the wind intensity also intensified on the TP, which resulted in the enhancement of dust generation, arid and windy condition, leading to the loess preservation and development on the TP. Moreover, numerous evidences suggested that the glaciers on the TP may significantly developed since 800 ka, then enlarged at 500–600 ka, which may lead to the massive dust/loess input to the TP, Chinese Loess Plateau and north Pacific Ocean. • Significant aeolian activity began at 584 ka in the southern Tibetan Plateau. • Extensive loess development on the Tibetan Plateau occurred between 1200 and 600 ka. • Global cooling during the mid-Pleistocene Transition determines extensive loess development. • Significantly developed glaciers lead to the massive dust/loess input to East Asia. [ABSTRACT FROM AUTHOR]

Sub-Antarctic glacier chronologies can provide valuable information about the past variability of climate dynamics in the Southern Ocean region. The Kerguelen Archipelago (49°S) is advantageously located under the influence of the Southern Hemisphere's westerly wind belt, thus fluctuations of climate-sensitive glaciers on Kerguelen can provide a baseline for understanding the behavior of this atmospheric regime in response to climatic forcings. We present 17 36Cl exposure ages of moraine and erratic boulders to provide chronological constraints to paleoglacier extents of the Guynemer cirque glacier, located just north of the Cook Ice Cap. Erratic boulders show ice thinning in the Guynemer region started to occur in the Late Glacial by 13.5 ka and continued past 12.4 ka. Ice retreat was punctuated by the formation of two moraine stages, the outermost at 11.5 ± 0.4 ka followed by another at 10.4 ± 1.2 ka, which are indicative of Early Holocene glacier advances/standstills. A glacial advance occurred at 1.4 ± 0.3 ka, which corroborates other Late Holocene re-advances elsewhere on the archipelago. Finally, three undated moraine stages are found between 1.4 ka and the 1960s. The lack of moraines after 10.4 ka and through the Mid-Holocene suggests that the Guynemer glacier was significantly smaller during this extended period of the Holocene compared to its Early Holocene as well as its Late Holocene limits. The Guynemer glacier history provides unique evidence of Early Holocene moraines on Kerguelen, which have not been discovered thus far on the archipelago. Similar to glaciers in Patagonia, New Zealand and South Georgia, the Guynemer glacier was at its largest Holocene extent in the Early Holocene. However, while other southern mid-latitude glacier chronologies show progressively smaller glacial extents throughout the Mid- to Late Holocene, the Late Holocene re-advance of the Guynemer glacier, like other Kerguelen glaciers, likely exceeded its Mid-Holocene extent. • We present 17 new 36Cl surface exposure ages from the Kerguelen Archipelago. • 36Cl ages range from 13.5 ± 0.3 ka to 1.2 ± 0.2 ka. • First early Holocene-dated moraines on Kerguelen. • Glacial readvance occurred in late Holocene. • Holocene glacial evolution on Kerguelen differs from other sub-Antarctic glaciers. [ABSTRACT FROM AUTHOR]

Knowledge of silicic acid concentrations at the surface Southern Ocean helps better understand the role of the biological pump in regulating atmospheric CO 2 concentrations in the past. While the silicon isotope compositions of diatom provide a measure of Si utilization efficiency, proxies on surface silicic acid concentration are not yet available. Here we determined the diatom frustule Al/Si ratio and dust flux to constrain the surface silicic acid concentrations in the Atlantic sector of the Southern Ocean. Our results based on multiple methods, including inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS), and nuclear magnetic resonance spectroscopy (NMR), suggest the isomorphic substitution of Al for Si by frustule biosynthesis. This enables us to transfer the diatom Al/Si ratio into seawater Al/Si ratio using the partition coefficient of Al between diatom silica and seawater. By further constraining dust flux using the sediment 230Th-normalized 232Th flux, we found that the markedly higher frustule Al/Si ratios cannot be solely explained by increased Al dissolution from dust and call for much lower surface silicic acid concentrations in the Antarctic Zone during the Last Glacial Period. The lower silicic acid concentration coupled with lower Si utilization efficiency inferred previously from silicon isotopes in the Antarctic Zone is likely due to the combined effects of reduced upwelling and iron-fertilization-regulated uptake stoichiometry, contributing to a lower atmospheric CO 2 during the Last Glacial Period. • Multiple lines of evidence support the isomorphic substitution of Al for Si in diatom frustule at ODP 1094. • Surface dissolved Al concentrations were constrained by the sediment 230Th-normalized 232Th flux. • Surface Si(OH) 4 concentrations were derived from the reconstructed seawater Al/Si ratios and dissolved Al concentrations. • Lower surface Si(OH) 4 concentrations were found in the Antarctic Zone during the last glacial period than in the Holocene. [ABSTRACT FROM AUTHOR]

Deep-sea pollen records from the Western European margin show that during the Last Glacial period (115-27 ka), regional vegetation oscillated between steppe and open forest in response to the millennial scale climate variability, Dansgaard-Oeschger (D-O) cycles and Heinrich events (HE), and that the magnitude of the forest expansions during D-O warming events was modulated by orbital parameters. However, little is known about the vegetation response in the northwestern Mediterranean region. Here, we present a new well-chronologically constrained high-resolution marine pollen record from the Gulf of Lion documenting the NW Mediterranean vegetation response during Marine Isotope Stages (MIS) 4 and 3. The pollen record highlights the strongest forest expansions during D-O 17-16 and D-O 8 in NW Mediterranean borderlands, likely driven by minima in precession. In this region, Heinrich Stadials (HS) 5 and 4 are marked by steppe landscapes while temperate forest surprisingly characterized HS 6. We hypothesize that the combination of minima in precession and local atmospheric and marine processes allows the development of the temperate forest in NW Mediterranean while the expansion of open environments occurred in other areas of Western Europe. In addition, our results support the hypothesis of Picea survival in NW Mediterranean during MIS 4 to 3. • Contrasting vegetation responses to D-O warming and cooling events. • Orbital configuration controls the magnitude of forest expansions to D-O warmings. • Forest-dominated landscape in NW Mediterranean borderlands during HS 6. • Forest expansion during HS 6 trigger by orbital and local processes. [ABSTRACT FROM AUTHOR]

Marine isotope stage (MIS) 16 (676-621 ka) and MIS 12 (478-424 ka) stand out as two significant glacial periods during the late Quaternary, demonstrating consistent continental ice volume or sea level, as discerned from benthic δ18O records. Intriguingly, the average sea surface temperature (SST) during MIS 16 surpasses that of MIS 12 by approximately 0.54–0.79 °C, while the atmospheric CO 2 concentration during MIS 16 is approximately 16 ppmv lower than that of MIS 12. The underlying mechanism driving these discrepancies remains enigmatic. In this study, we present new high-resolution X-ray fluorescence (XRF) and grain size records covering the interval from 700 to 400 ka from Ocean Drilling Program (ODP) Site 1090 in the South Atlantic Ocean. We also integrated benthic δ13C, ice-rafted debris (IRD) and carbonate ion concentration ([CO 3 2−]) records globally, to elucidate the distinct climate evolution during the MIS 16 versus MIS 12. Our findings suggest that MIS 12 is distinguished by a more substantial Antarctic ice-sheet, coupled with a weakened and/or equatorward displacement of southern westerly winds, and expansion of southern source water (SSW) alongside contractive northern source water (NSW). Conversely, the opposite climate state can be observed in MIS 16. The elevated atmospheric CO 2 in MIS 12 and diminished atmospheric CO 2 in MIS 16 may be attributed to reconfigurations in the ocean carbon reservoir regulated by the reorganization of deep-water masses and meridional ocean circulation, as a result of the divergent evolution of bipolar ice-sheets. Our study underscores the critical role of the interplay between the two polar regions in modulating deep-sea carbon storage on the orbital timescale and atmospheric CO 2. This interplay is essential for a comprehensive understanding of past and future carbon cycle adjustments in response to climate change. • We present a comparative analysis of MIS 16 and MIS 12 climates. • SST in MIS 16 surpasses that of MIS 12, yet CO 2 levels in MIS 16 are lower. • Grain size and XRF data from ODP Site 1090 (700-400 ka) are provided. • The reduced CO 2 in MIS 16, compared to MIS 12, is ascribed to bipolar carbon cycle control. [ABSTRACT FROM AUTHOR]

Sites of ice-stream discharge to the continental slope build trough-mouth fans from glacigenic debris flows (GDFs), subglacial meltwater flows, and suspended sediment. Thus, past ice configurations may be interpreted from the sedimentological record. This study links the records in cores, high-resolution seismic profiles, and multibeam swath bathymetry of Hatton Slope and Fan to the changing glaciological history in Hudson Strait, one of the largest ice streams of the late Pleistocene Laurentide Ice Sheet. 14C-AMS dates, X-ray fluorescence geochemical profiles, and oxygen isotopes in sixteen cores document sediment supply during the last glacial cycle, and earlier history is interpreted from seismic data. The Frobisher Bay slope sector has a long record of GDF deposits from severe glacial periods between MIS 6 and 22, with little impact of meltwater discharge. Mass-transport events and aggrading gravel-floored valleys dominate the northern Hatton slope sector. The central slope sector shows the greatest shelf break progradation by till deposition, with kilometre-spaced gullies heading at 700–730 mbsl from the last major grounding of the ice-stream on the upper slope during Heinrich event 3 (H3). The gullies pass downslope into ∼5 km wide valleys, which have been sites of sediment bypass since widespread meltwater flow in MIS 6 and show little aggradation since MIS 16. Intervening >50 m high ridges show alternating levee accretion and erosion by shallow mass-transport events. Downslope on Hatton Fan, GDFs are common and fill wide erosional channels that lead to the sandy braid plain of the central Labrador Sea. The channels of the southern sector and Saglek Slope have channeled turbidity currents down the NAMOC, and stratified contourite deposits accumulated on the fan. Over the MIS 1–3 period widely represented by cores, ice was grounded in Hatton Basin and on the upper slope to 700 m water depth only immediately prior to H3. Older and younger H events had a floating ice-shelf in Hatton Basin, and sedimentation was dominated by the retreat of that ice shelf to Resolution Island. Distal cores show no systematic difference between the H1–top H3 interval and the base H3–H5 interval. Given the supply of carbonate detritus of consistent composition back to at least H5, any MIS 3 deglaciation of Hudson Bay would require improbably high growth rates of ice sheets in the centre of the continent. • First multibeam swath bathymetric and seismic profiling of the Hudson Strait Ice Stream. • Glacigenic debris flows, and mass-transport events were outlined during MIS 6 and 16. • Glacial ice was grounded in Hatton Basin and on the upper slope to 700 m over MIS 1-3. • Lack of a systematic difference between H1–H3 and H4–H5 events raises the question about the deglaciation hypothesis during MIS 3. [ABSTRACT FROM AUTHOR]

Antarctic fjords and coastal bays are excellent traps for sediment and represent key areas for high-resolution investigation of past environmental conditions. Robertson Bay is an understudied coastal area located at the confluence of the Ross Sea and the Southern Ocean. Recently obtained seafloor morphology data indicate the presence of a cross-shelf elongated valley, composed of three minor basins separated by sills and seabed ridges with an arcuate shape. Several cores were collected within the basins, and investigated using a multiproxy approach including sedimentological, chemical, geochemical, and micropaleontological characterization to reconstruct the paleoenvironmental evolution from the last glacial period to present. The ages of two of these cores are constrained using ramped pyrolysis oxidation radiocarbon dating. Four sedimentary facies were recognised from which we developed a sedimentary model covering the last 21,000 years (21 ka BP). Our record provide evidence for a covering ice shelf cover from 21 to 16.5 ka BP, which gradually receded between 16,5 and 11 ka BP due to the progressive intrusion of modified Circumpolar Deep Water, thereby promoting the formation of Ice Shelf Water and High Salinity Shelf Water. From 11 to 5,8 ka BP, the ice shelf continued shrinking and nutrient-rich of modified Circumpolar Deep Water penetration onto the continental shelf progressively favoured diatom blooms and a general increase in primary productivity until 5.8 ka BP. The Late Holocene is characterised by an alternation of prolonged sea ice cover with stratified water column and strong bottom current with prolonged sea-ice free season with the intrusion of modified Circumpolar Deep Water and very slow energy bottom current. • First paleoenvironmental study from the LGM to the present in Robertson Bay. • Strong impact of regional ice sheet recession on environmental conditions and productivity. • Multiproxy approach constrained by Ramped Pyrolysis based age model. • The coastal bay area was studied by sediment cores and geophysical data. [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]

The repeated cut-and-fill process induced by the late Quaternary glacial damming and catastrophic outburst events in the Yarlung Tsangpo Gorge (YTG) in the eastern Himalaya may reflect the interaction between rock uplift, climate change and river incision in the southeastern Tibetan Plateau. Here we provide the detailed reconstruction of the cut-and-fill history recorded at the entrance of the YTG, based on geomorphological, sedimentological and chronological analyses. The results reveal a catastrophic glacial-dam breach during the last deglaciation (∼18 ka), and the outburst flood eroded a ∼30–45 km long valley floor filled with glacial diamicton and glaciofluvial deposits, which was later further incised to form terrace T 2 with a height of ∼350 m. The second dam failure occurred at ∼5 ka, producing a spillway, forming terrace T 1 with a height of ∼100 m. The vertical incision and horizontal migration rate of the knickpoint at the glacier dams were estimated as 0.02 m/yr, and 2.5 m/yr since the last deglaciation, based on the age of the terraces and distance of the knickpoints. We consider the glacial dams to be effective in impeding headward river erosion during glacial periods. This, along with rapid river headward erosion during the last interglacial period, results in two knickpoints on the longitudinal profile due to the differences in erosion resistance. The fluvial reaches corresponding to the repeated cut-and-fill processes are confined to the center of the Namche Barwa massif, suggesting that rapid rock uplift counteracted fluvial headward erosion and maintained the stability of the bedrock knickpoint. Therefore, in comparison to glacial dams, tectonic uplift is the most important component in plateau margin stabilization. • Two primary terraces have developed in the Yarlung Tsangpo Gorge since the last glacial period. • Vertical and horizontal migration rate of the knickpoint were estimated as 0.02 m/yr, and 2.5 m/yr. • Glacial dams have impeded erosion of bedrock channels, resulting in two knickpoints on the profile. • Maintaining stability of knickpoints over millions of years requires long-term continuing rock uplift. [ABSTRACT FROM AUTHOR]

Reconstructing mountainous landscape evolution throughout the Quaternary is challenging because of the poor long-term preservation of geomorphic records in a context of rapid surface dynamics and topographic rejuvenation. The Quaternary geomorphic evolution of the western European Alps has been strongly controlled by climatic oscillations between glacial and interglacial periods. Significant erosion and sediment remobilization during these glacial/interglacial cycles have left very few sedimentary archives to quantify the surface dynamics and paleo-environmental conditions within the mountain belt over the last hundreds of thousands of years. Alpine valleys within the periglacial zone are potential candidates to target long-term geological archives, since they may contain alluvial deposits that have been preserved from subsequent glaciations. In the Drac valley (French western Alps), three generations of paleo-valleys are preserved, each of which was filled with alluvial and lacustrine sediments in response to glacial damming downstream. The valleys were incised during subsequent times of glacial retreat, leading to the formation of epigenetic valleys. Detailed 3D mapping of the paleo-valleys was carried out using photogrammetric models to constrain their geometry. Mapping was combined with luminescence dating of alluvial deposits to reconstruct the temporal evolution of the Drac valley. This chronological framework, together with additional data from the literature, allowed us to quantitatively constrain the complex alluvial dynamics along the Drac river during the last ca. 230 ka. Poly-phased alluvial deposition occurred in the most recent paleo-valley between ca. 90 and 20 ka (i.e., from late MIS 5 to MIS 2) in a context of global climate cooling and major Alpine glaciation. Sediment infilling of the intermediate paleo-valley is dated at around 130 ka; i.e., during the late-glacial phase of the penultimate glaciation, at the abrupt warming transition between MIS 6 and MIS 5. Finally, the oldest paleo-valley was filled around 230 ka (during a sub-stage of MIS 7) probably in a cooling and glacial context. The overall alluviation pattern and chronology of the study area highlight the asynchronous and partially contrasting glacial dynamics between the different glacier systems (i.e., Drac, Bonne and Romanche/Isère glaciers) within the Ecrins-Pelvoux massif of the French western Alps. • Record of Pleistocene epigenic paleo-valley evolution in the French western Alps. • Alluvial sediment aggradation recorded during early, pleni & late-glacial periods. • Diachronous response of local Alpine glaciers to Pleistocene climate forcing. • Long-term estimate of fluvial incision rate (0.6–0.8 mm/yr) over the last 250 ka. [ABSTRACT FROM AUTHOR]

The formation and evolution of the cryosphere on the Tibetan Plateau is of great significance in understanding the Earth's carbon and climatic system. Periglacial loess deposits in southeastern Tibet offer a means to constrain this history as they contain critical information on glacial grinding and frost shattering processes in high-altitude mountain regions through time, which yield lithogenic fractions of largely loess silts and sands. Based on combined analyses of lithogenic magnetic properties and mineralogical composition, here we find that increasing high mountain production and supply of fresh detrital components since the mid-Pleistocene climate transition (MPT, 1.2–0.7 Ma) led to a substantial increase of the lithogenic susceptibility and decrease in chemical weathering intensity of periglacial loess in southeastern Tibet. The agreement of these findings with similar results from eolian loess on the northern margins of the Tibetan Plateau suggests a plateau-wide glacier expansion during the MPT. Enhanced glacial erosion and freeze-thaw activities occurred in the high-altitude mountain regions of the plateau during the MPT, thereby providing vast amounts of fresh detritus for the formation of loess deposits. High and constant values of lithogenic magnetic parameters in the loess deposits after 0.7–0.6 Ma further indicate that the Middle Pleistocene is a critical period for the establishment of modern-like glacial and periglacial landforms on the Tibetan Plateau. Our results further suggest that enhanced Quaternary glaciation in SE Tibet occurred earlier than in the north, which we attribute to climate cooling combined with regional seasonal snowline lowering. As such, a close relationship exists between global climate changes, development of pan-Tibetan glaciations, and large-scale dust emission. • Lithogenic magnetic enhancement of periglacial loess in SE Tibet occurred during the middle Pleistocene. • Increased supply of fresh detritus due to enhanced glacial erosion caused the lithogenic magnetic enhancement. • Onset of Quaternary glaciations in the SE Tibet earlier than in the northern Tibetan Plateau. • Middle Pleistocene is a critical period for the evolution of the cryosphere in the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

This study focuses on the sedimentological and stratigraphic description and chronology of Pleistocene coastal deposits on the Pityusic Islands (Balearic Islands, Spain). These deposits show evidence of interference between processes characteristic of alluvial, marine, and aeolian environments. Optically stimulated luminescence dating of aeolian levels indicates that deposition took place from the Lower to Upper Pleistocene. The sedimentological and chronological analysis of these deposits allows reconstruction of coastal Pleistocene environmental history from MIS 22 to MIS 2. The results show that changes in the average wind direction over time, modulated by the interaction with coastal relief orientation, were the main controls on the Lower to Upper Pleistocene coastal landscape evolution on the Pityusic Islands. The main episodes of aeolian activity identified in the Western Mediterranean, can be linked to periods of low sea level. The study's findings the presence of two dominant environments, coastal aeolian and alluvial, each characterized by distinct geological processes. Interestingly, these processes have led to the formation of deposits that exhibit a combination of characteristics from both environments. Moreover, these deposits retain elements inherited from each environment in terms of sedimentary supply, precipitation, runoff or aeolian transport. These results corroborated by OSL dating provide a useful indicator of the geomorphological processes and changes that occurred during the Pleistocene, unraveling the environmental evolution, and contributing to the growing knowledge on western Mediterranean aeolian or aeolian-alluvial interacting environments during the last 1000 ka. • The influence of glacioeustatic sea level variation on coastal landscape evolution in the Mediterranean basin. • Optically stimulated luminescence dating of the Pleistocene deposits of Pityusic Islands (MIS 22 to 2). • Arid and cold stages (glacial stages-lowstand periods) are represented by the development of the dune system. [ABSTRACT FROM AUTHOR]

The sparsity of high-resolution 10Be chronologies in the Northern Hemisphere makes it difficult to determine whether the global fluctuations in glacier extent during the last glacial occurred simultaneously. This limits our understanding of the past mechanisms driving global climate changes. We compiled and reanalyzed 476 10Be exposure ages from the southern Tibetan Plateau for the last glacial and compared them with coeval 10Be ages from the Southern Alps. The results indicate an anti-phase relationship between the glacier expansions in these two regions on the millennial-scale during the last glacial period. Comparison with a glacier-derived temperature reconstruction suggests that maintaining a stable glacier state in both regions required a similar cooling magnitude. We speculate that variability of the Atlantic Meridional Overturning Circulation, which induced poleward/equatorward shifts in atmospheric and oceanic circulation, was the primary driving mechanism of this anti-phase relationship. Our findings provide glacial geological evidence to support the bipolar seesaw hypothesis. • Anti-Phase glacier expansion on the millennial-scale between the two regions. • Glacier-derived temperature reconstruction reveals a similar cooling magnitude. • Atlantic Meridional Overturning Circulation change may be the principal cause. [ABSTRACT FROM AUTHOR]

The lake state and chemistry are sensitive to climate change at short timescales, but it is unclear how lake hydrochemistry responds to monsoonal climate, especially over glacial-interglacial cycles, owing to lack of well-dated and continuous sedimentary records. The types and geochemical compositions of authigenic carbonates from lacustrine sediments can be used to reconstruct past hydrochemistry. Yet, little is known about the significance and influencing factors of the Mg/Ca and Sr/Ca ratios of authigenic carbonates over glacial-interglacial cycles. Here, trace-element data of a 666 m long sediment sequence from the Heqing basin, a paleo-lake situated at the southeastern margin of the Tibetan Plateau, provide detailed glacial-interglacial hydrochemical conditions and their association with Indian summer monsoon (ISM) evolution during the entire Pleistocene. In interglacials, variation in both Mg/Ca and Sr/Ca ratios can serve as proxies for salinity as a result of precipitation of low-Mg calcite, constrained by enhanced ISM intensity and catchment weathering product. Instead, in glacials, high Mg/Ca and Sr/Ca ratios reflect high-Mg calcite and aragonite precipitation under low lake level conditions. There is a nonlinear response of the Sr/Ca ratio of lacustrine sediment to salinity variation when high-Mg calcite and aragonite precipitate in a hydrologically closed and evaporative lake. Based upon the sedimentary Sr/Ca and Mg/Ca ratios in the Heqing paleo-lake, the lake hydrochemistry during the Pleistocene experienced obvious glacial-interglacial ISM cycles at the life span of the lake itself: (1) in the old interval (2640–1840 ka), the salinity was low with cycles at the early stage of lake development owing to strong ISM; (2) in the middle interval (1840–920 ka), the lake was at a balance state and its salinity was more constrained by weathering solute, rather than ISM; and (3) in the young interval (920–130 ka), the salinity fluctuated with large amplitude over glacial-interglacial cycles and subsequent increase paced the weakened ISM. This study highlights the sensitivity of the types of lacustrine authigenic carbonates and lake chemistry to ISM changes over glacial-interglacial cycles. • In the monsoon-impacted areas, sedimentary Mg/Ca and Sr/Ca ratios controlled by ISM intensity and catchment weathering. • Mg/Ca ratios of lacustrine sediment reflect the types of authigenic carbonates over glacial-interglacial cycles. • Sr/Ca ratios of lacustrine sediment record salinity linearly in the interglacials, but nonlinearly in the glacials • Through time, lake hydrochemistry response to catchment weathering gradually decreased. [ABSTRACT FROM AUTHOR]

During the last deglaciation, collapse of the saddle between the North American Cordilleran and Laurentide ice sheets led to rapid ice-sheet mass loss and separation, with meltwater discharge contributing to deglacial sea-level rise. We directly date ice-sheet separation at the end of the saddle collapse using 64 10Be exposure ages along an ∼1200-km transect of the ice-sheet suture zone. Collapse began in the south by 15.4 ± 0.4 ka and ended by 13.8 ± 0.1 ka at ∼56°N. Ice-sheet model simulations consistent with the 10Be ages find that the saddle collapse contributed 6.2–7.2 m to global mean sea-level rise from ∼15.5 ka to ∼14.0 ka, or approximately one third of global mean sea-level rise over this period. We determine 3.1–3.6 m of the saddle collapse meltwater was released during Meltwater Pulse 1A ∼14.6-14.3 ka, constituting 20–40% of this meltwater pulse's volume. Because the separation of the Cordilleran and Laurentide ice sheets occurred over 1–2 millennia, the associated release of meltwater during the saddle collapse supplied a smaller contribution to the magnitude of Meltwater Pulse 1A than has been recently proposed. • Cordilleran-Laurentide ice-sheet separation began before ∼15.5 ka. • Cordilleran-Laurentide ice-sheet separation ended by ∼13.8 ka. • The 1–2 kyr duration means separation had a modest impact on abrupt sea-level rise. [ABSTRACT FROM AUTHOR]

The melting of the Greenland ice sheet (GrIS) is a major contributor to past and future global sea-level rise. Understanding the response of the GrIS to times in the past when temperatures were as warm or warmer than today offers insights into its current and future response to climate change. In the southwest sector, the GrIS retreated inland beyond its current margin during the (at least regionally) warmer-than-present mid-Holocene, before it readvanced to the historical maximum position during the Little Ice Age. This was then followed by a slight retreat to its current position. To investigate the timing and magnitude of southwest GrIS retreat and readvance in response to Holocene warmth, we model the response of the solid Earth and local relative sea level (RSL) to past ice sheet change. We test a suite of eleven ice sheet scenarios that are based on ICE-6G_C but are modified in the timing and magnitude of ice retreat and readvance and pair them with four different viscoelastic Earth structures. We compare model predictions to observations of paleo sea level, present-day sea-level change, and present-day vertical land motion (VLM) around Nuuk, Greenland. We find that the modeled timing and magnitude of the Holocene retreat and readvance have a significant impact on modern sea-level change and VLM in Nuuk. Models that assume a readvance approaching the southwest GrIS' historical maximum between 2 and 1 ka are most consistent with observations. The RSL response, however, is less sensitive to the timing of the minimum GrIS extent. Nonetheless, better data-model fits are generally obtained when the minimum ice sheet extent is reached between 5 and 3 ka, within the tested range of 6-3 ka. Comparing this timing to local and regional records of temperature and ice-sheet change suggest that the evolution of the southwestern GrIS presented here was in-phase with the likely evolution of southwestern GrIS mass balance through the Holocene. Our results have implications for future ice sheet modeling studies targeting southwestern Greenland by providing additional constraints and strengthening existing ones. Moreover, this work provides a deeper understanding of the interactions between the climate and the cryosphere and thus of future ice sheet change. • We constrain Holocene Greenland ice sheet behavior using GIA modeling and local data. • Southwest Greenland Holocene minimum extent likely occurred between 5 and 3 ka. • Southwest Greenland historical maximum extent was likely approached between 2 and 1 ka. • Holocene Greenland ice margin evolution was likely in-phase with regional temperature records. [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]

Understanding past changes in oceanic circulation and the corresponding heat, salt delivery variations are essential for assessing the climatic roles of ocean dynamic processes since the last glacial period. Unravelling salinity budget variation in the North Pacific and its controls is important to better understand the North Pacific Intermediate/Deep Water formation and associated climate impacts. The Tsushima Warm Current (TWC), the northernmost Kuroshio branch entering the semi-closed Japan Sea through the shallow strait, is regarded as a fundamental component for oceanographic changes in the Japan Sea. To obtain a comprehensive history of the Japan Sea salinity budget, this study reconstructed the evolution history of the TWC inflow by compiling paleo-hydrographic records in the Japan Sea. Following a persistent but weakened TWC inflow during Marine Isotope Stage 3, radiolarian assemblage data revealed that the TWC taxa disappeared since ∼30 thousand years ago (ka). The synchronous onset of the low salinity anomaly event was in response to the cutoff of saline TWC inflow due to the rapid fall in global sea level at 30 ka. Extreme restriction of seawater exchange caused a persistent freshening of the glacial Japan Sea and formed a low-salinity water mass in the upper ocean. The compiled paleodata confirmed that the Japan Sea accumulated excess freshwater during the glacial sea-level lowstands and the low-salinity pool extended downward to ∼900 m depths. Coinciding with the peak of the low salinity anomaly event, re-emerging TWC inflow after 19 ka reflected the reconnection of the open ocean to the Japan Sea. The persistent TWC inflow mainly drove the reduction in magnitude of the deep low-salinity pool during the last deglaciation. As a large and isolated freshwater sink for the glacial North Pacific, the deep low-salinity pool evolution could potentially have strong impacts on the North Pacific salinity budget and subsequent large-scale circulation. • Radiolarian reconstruction indicates a persistent but weakened influence of the TWC inflow in the Japan Sea during MIS 3. • The low-salinity pool extended downward to ∼900 m depths in the Japan Sea during the LGM. • The link between global sea-level change and deep low-salinity pool evolution is sought. [ABSTRACT FROM AUTHOR]

The Piacenzian – Gelasian transition is a time of profound changes in the Earth's climatic regime, epitomized by the definitive establishment of large ice caps in the Northern Hemisphere and the beginning of the "ice ages" at ca. 2.6 Ma. This event is sharply documented in δ18O records globally by a prominent triplet of severe glacial events (MIS 100, 98 and 96) that approximate the base of the Gelasian Stage. We have reconstructed a multi-species planktic and benthic foraminiferal δ18O and δ13C record from the Monte San Nicola section (Sicily) across the Piacenzian/Gelasian boundary, with the purpose of better constraining in time the main marker criteria for recognition of the Gelasian GSSP (Global Boundary Stratotype Section and Point) and investigating in detail the paleoclimatic and paleoceanographic response of the central Mediterranean to the definitive onset of the Northern Hemisphere Glaciation. Our results confirm the reliability and usability of the criteria originally proposed for defining the Gelasian GSSP, and significantly improve their chronology and chronostratigraphic positioning. Beyond an obvious alternation of obliquity-driven glacial-interglacial cycles, our isotopic record unraveled a pervasive climate variability in the suborbital time domain, the origin of which is still ambiguous. Altogether data presented in this paper provide the first high resolution isotopic records shedding new light both on the stratigraphic and paleoclimatic evolution of the Central Mediterranean area at the beginning of the Northern Hemisphere Glaciation. • A multispecies d18O and d13C record was reconstructed from Monte San Nicola (Sicily). • First isotopic record ever across the base Gelasian, ca. 2.7 to 2.5 Ma (MIS G5 to MIS 99). • Stratigraphic position of the Gelasian GSSP and its proxies was confirmed, their age improved. • Suborbital variability was found in glacial MIS 104 and 100, probably driven by the N. Atlantic. • Suborbital signals also occur in interglacial MIS G1, with ambiguous origin. [ABSTRACT FROM AUTHOR]

The megaflooding caused by outbursts from Late Quaternary glacially-dammed lakes in the Yarlung Tsangpo Gorge (YTG) potentially shaped the fluvial landscape and controlled the geodynamic evolution of the Namche Barwa Syntaxis in the eastern Himalaya. However, the sedimentary evidence for such flooding in the narrow reaches of the Yarlung Tsangpo River (YTR) valley has been lacking. In this study we conducted geomorphological and sedimentological analyses of the Motuo stretch of the YTR downstream of the Yarlung Tsangpo Gorge and combined these with dating results to identify multistage high magnitude outburst paleofloods. One megaflood event was found to have occurred at ∼5 ka, with a minimum discharge of ∼1.1–4.4×106 m3/s. Our results suggest that this event exceeded 1000 km in range, and was consistent with the age of flood deposits downstream, where the YTR becomes the Siang-Brahmaputra River. Evidence of older and younger flood deposits was also obtained. The erosion caused by this megaflood was stronger in the steep river channel that flows through the uplift center of the Namche Barwa Massif. This may have been principally a response to the differential uplift caused by the main boundary faults. The megaflood event also gave rise to the headward erosion of the YTR's northern tributaries. The megaflood sediment zone is concentrated in the middle and lower reaches of the YTR where the valley widens. Here, the gradient of the river channel is shallower, potentially reflecting weaker tectonic activity accompanied by slower fluvial erosion. Furthermore, multistage catastrophic floods from the Yarlung Tsangpo Gorge may have significantly impacted any downstream prehistoric human settlements. • Multiple phases of last glacial paleoflood sediments found in downstream of Tsangpo Gorge. • Paleoflood event at ∼5 ka BP with maximum height of terrace ∼250 m above modern river level. • Erosion caused by outburst flooding is a response to differential uplift of the Namche Barwa massif. • Steep sides of Yarlung Tsangpo Gorge and its tributaries formed by paleoflood erosion. [ABSTRACT FROM AUTHOR]