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The seasonality of the East Asian monsoon is characterized by the coexistence of warm and humid summers and cold and dry winters. However, the current understanding of when and why the seasonality of the East Asian monsoon occurs is poor. Hydroxy-interlayered vermiculite (HIV), which is formed under conditions of low soil organic matter content, pH values between 4.6 and 5.8, and oxidizing states with frequent wetting‒drying cycles, may serve as a potential indicator of monsoon seasonality variation. In this study, we present detailed mineralogical and micromorphological investigations of HIV collected from an eolian sequence on the Chinese Loess Plateau (CLP) to explore the evolution of East Asian monsoon seasonality. The mineralogical results deduced from X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy show that a transition from chlorite to HIV occurred at ∼1.8 Ma. Moreover, the authigenic origin of HIV, as indicated by the presence of many neatly arranged flakes in the SEM images and the presence of irregularly interstratified chlorite-HIV observed via transmission electron microscopy (TEM), collectively imply that HIV is the weathering product of chlorite. This transition from chlorite to HIV generally reflects an increase in monsoon seasonality on the CLP since ∼1.8 Ma, which may be caused by the contemporaneous uplift of the northeastern Tibetan Plateau, or global cooling in combination with La Niña-like sea-air interactions. Our study suggests that the HIV serves as an effective index for monsoon seasonality reconstruction, thus providing a new insight into Asian monsoon dynamics. • Hydroxy-interlayered vermiculite (HIV) formed with frequent wetting–drying cycles. • HIV is a potential indicator of seasonal variation in the East Asian monsoon. • A transition from chlorite to HIV commenced at ∼1.8 Ma on the Chinese Loess Plateau. • Enhanced East Asian monsoon seasonality has prevailed since 1.8 Ma. [ABSTRACT FROM AUTHOR]

The Plio-Pleistocene transition (1.5–3 million years ago, Ma) is marked by a ⁓140 ppm drop in atmospheric CO 2 levels, leading to a long-term global cooling. Excess production of organic carbon (OC) from terrestrial vegetation, followed by transport and burial, is responsible for the CO 2 decline. The role of wildfire triggering uptake of atmospheric CO 2 is proposed for the first time as a viable mechanism to explain vegetational shift, erosion, and burial of OC. Here, we quantified the impact of Fire-Induced Effects (FIE) on the OC burial rates both in the regional and global scales during the interval 4 to 1.5 Ma. A survey of record from Nicobar Fan serves as an ideal burial ground for terrestrial carbon storage due to the deposition of OC derived from wildfire events occurring over the South Asian region. The multi-proxy approach reveals a notable intensification of wildfire activity during the Plio-Pleistocene transition, accompanied by respective 2.9 and 2.4-fold rises in the rate of continental erosion and OC burial fluxes compared to the early Pliocene. On a global scale, we constructed a global wildfire stack using 19 wildfire proxy records sourced from continental and marine sediments. We calculated the global OC burial rate using sediment OC content and Mass Accumulation Rate data from 23 ODP/IODP sites worldwide. Our global data also indicate a 4.8-fold surge in wildfire activity and a 1.5-fold increase in global OC burial rates, from 2.29 ± 0.48 Mt C a−1 in the early Pliocene to 3.52 ± 0.80 Mt C a−1 at the Plio-Pleistocene transition. Our research underscores the pivotal role of FIE in atmospheric CO 2 drawdown, which has been seldom discussed in previous studies. • Enhanced wildfire activity over South Asia during the Plio-Pleistocene transition. • Intensified wildfires and organic carbon burial occurred on a global scale. • Fire-Induced Effect (FIE) played a key role in the drawdown of atmospheric CO 2. [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]

The future impact of global warming on tropical arid regions is unclear due to uncertainties about the correlation between rising temperatures and changes in precipitation patterns. A critical factor is the reliability of the sedimentary chronologies. Hence, to better understand the potential long-term consequences of climatic warming or cooling for tropical arid regions we compared a pollen record from the annually-laminated sediments of a crater lake in Myanmar with ice core records of the Siberian High, both of which have an annual resolution. Our findings reveal that over the past 8000 years, the Myanmar region experienced six significant drought events, three of which coincided precisely with intensifications of the Siberian High-pressure system. Furthermore, five out of these six events were synchronous with the North Atlantic Bond events within the limit of the dating uncertainties. Conversely, warm periods were associated with increased precipitation along with relatively short-lived drought events. Our findings suggest that regardless of the El Niño intensity, a cooling trend in the Northern Hemisphere may result in persistent extreme drought conditions in arid tropical regions. Therefore, as well as the environmental implications of global warming, it is also important to address the potential hazards associated with cooling, especially in arid tropical regions. To facilitate effective disaster management and to develop strategies for climate change mitigation, it is crucial to better understand the complex relationship between temperature fluctuations and drought. Overall, our findings are a reminder of the importance of not ignoring the potential disasters that may arise from cooling trends while focusing exclusively on warming. • Six drought events have been identified using pollen from annually laminated sediment records. • A comparison between droughts and cooling events from annually laminated records is conducted. • Three out of the six drought events align precisely with cooling events over the last 8000 years. • Cooling-induced droughts may pose a greater threat compared to those caused by warming. • The exact relationship between drought and El Niño events remains challenging to determine. [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]

We present a detailed analysis of the craniomandibular and dental remains of Mesotherium cristatum , the quaternary mesotheriid typotherid notoungulate, from Corralito, Santa María Department, Cordoba Province. This population represents the final lineage of Typotheria during middle Pleistocene, Post-Ensenadan Age (>220 ± 13 ka). We compared these new craniomandibular and postcranial samples from Corralito with those from Toscas del Río de La Plata, as well as other localities in the province of Buenos Aires dating to the Ensenadan Age 1.98–0.4 Ma). Our investigation reveals a substantial decline in the size and body mass of the last known population of M. cristatum during the Bonaeran Age period, before its extinction. This occurrence, hitherto unrecorded in any prior South American Land Mammal Age leading up to extinction, might be attributed to the climatic and abiotic changes of the Pleistocene. These changes notably caused a marked reduction in the paleobiogeographical distribution area of M. cristatum during the Middle Pleistocene. This size and body mass reduction, possibly an outcome of compelled reproductive isolation, is situated against the context of global cooling and heightened predatory pressures. Moreover, our analysis unveiled distinctive taxonomic attributes specific to this taxon, we compare dental size and find a preliminary evidence of an accelerated tooth replacement pattern. Furthermore, we have effectively updated the faunal composition information of the Corralito deposit, elucidating previous biostratigraphic inferences that had led to the belief of Corralito being an Ensenadan Age site. This adjustment impacts the first appearance datum (FAD) of the Neolicaphrium recens proterotheriid litoptern, younger than previously estimated and revised Bonaerian-Lujanian. Finally, this study provides insights into the biological analysis of the iconic species M. cristatum , prevalent in the South American quaternary of the Pampean region. It unreveils new faunal features specific to the Pampean region, shedding light particularly on the lesser-explored western area. These findinngs provide crucial insight into the ever-evolving ecosystem dynamics during the Middle Pleistocene. • The Mesotherium cristatum population from Corralito (Middle Pleistocene) present lower body mass than younger Lower Pleistocene (Ensenadan) populations. • The size and morphological variation during ontogeny of M. cristatum is greater than expected. • Mesotherium cristatum has a different nasal conformation than other members of the mesotheriidae family. • Mesotherium cristatum is the most abundant species over >50 kg of all the species present in Corralito site. • Ruling out the Ensenadan Age in Corralito sediments, Neolicaphrium recens (Litopterna) is not present in the Ensenadan sediments as was traditionally considered, but Bonaeran-Lujanian temporal range. [ABSTRACT FROM AUTHOR]

To explore the relationship between the global cooling, westerlies, and central Asian aridity, we report ∼1.1 Ma local sedimentary environment changes according to physical-chemical parameters from an 800-m core (KT11) from the Kashgar region in the western Tarim Basin, China. Grain size end-member (EM) modelling is employed to quantify the processes of sediment transport and deposition. Four end members with modal values of 272 μm, 144 μm, 45.6 μm and 12.7 μm were extracted and explained 97.9% of the variance in the grain size data, corresponding aeolian dynamics, river energies, delta development and pedogenesis/long-term suspension components transported by wind or water, respectively. Four dominant sedimentation types, including lacustrine facies, delta facies, fluvial facies, and aeolian dunes, were identified through lithology and grain size frequency curves. The 1.1 Ma sedimentary successions experienced delta deposits interbedded with fluvial and aeolian deposits and lacustrines (1.1–0.6 Ma), alternating fluvial and aeolian facies with the occurrence of deltas and lacustrines (0.6–0.15 Ma), and aeolian facies interbedded with deltas and fluvial facies (0.15 Ma-present). Stepwise drying sedimentary conditions and enhanced desertification indicated by increasing rubidium/strontium ratios and proportion of aeolian sands, and decreasing total organic carbon since the past 1.1 Ma, implied intensified westerlies, likely resulted from ice volume expansion and ongoing global cooling according to geological record comparison and simulations during the Last Glacial Maximum compared to preindustrial conditions, which may have controlled the expansion of the permanent deserts in inland Asia. These persistent drying trends and intensified westerly circulation in arid regions during glacial periods after the mid-Pleistocene Transition indicated by larger amplitudes of aeolian sand proportion than prior to 0.6 Ma are similar to those in the interior monsoonal Asia, where the larger-amplitude of median grain size indicated enhanced Asian winter monsoon intensity and drier glacials. • Dominant sedimentation types are identified. • Westerly aridity is reconstructed since mid-Pleistocene. • Concurrently enhanced westerlies and winter monsoon is proposed. • Records and simulations show westerly aridity driven by global cooling. [ABSTRACT FROM AUTHOR]

The mid-Holocene environmental transition was characterised by global cooling and the abrupt weakening of the Northern Hemisphere monsoon systems. It is generally considered the key driver of the collapse of several mid-Holocene agricultural societies, on a global scale. However, only a few previous studies have tried to verify the climatic origin of the collapse of these societies, using the compilation of spatiotemporal data at a large scale. Especially, the nature of mid-Holocene human-environment interactions in the climatically-sensitive margin of the East Asian summer monsoon front remains to be thoroughly understood. However, a systematic compilation of archaeological data at a regional scale can be used to verify the role the mid-Holocene environmental transition played in the collapse of late Neolithic cultures in China. Here, we present a regional compilation of Holocene records from sub-aerial sedimentary deposits, lake sediments, and archaeological sites in the deserts of NE China and the adjacent regions to explore human-environment interactions during the mid-Holocene. Comparison of the records of Holocene climate change with the evolution of archaeological sites reveals that the mid-Holocene environmental transition resulted in ecosystem degradation in the deserts of NE China, rendering these areas much less habitable. Faced with substantially increased environmental pressures, the late Neolithic inhabitants used several subsistence strategies to adapt to the environmental transition, including change in agricultural practices and ultimately migration. Overall, our results support the view that a widespread mid-Holocene drought destroyed the rain-fed agricultural and/or plant-based subsistence economies, ultimately contributing to the collapse of late Neolithic cultures in NE China. [ABSTRACT FROM AUTHOR]

Palynomorphs, including pollen and dinoflagellate cysts from marine sediments, can provide a history of paleoclimate and paleoceanography. We present new palynological profiles based on a core from the Integrated Ocean Drilling Program Site U1430, which was drilled in the Ulleung Plateau East Sea. This core covers the past 2 Ma and spans the Mid-Pleistocene Transition (MPT, 1.2–0.8 Ma) and Mid-Brunhes Event (MBE, ∼0.43 Ma). Terrestrial and marine palynomorph records indicate orbital-scale variations in paleoclimate and paleoceanography, reflecting changes in the interconnections between vegetation, climate, and the ocean. Before the MPT, the high pollen taxa ratio and abundant temperate pollen suggest a relatively warm temperature associated with astronomical forcing-induced insolation changes. At ca. 1.3 Ma, boreal coniferous pollen increased, suggesting intensification of the East Asian winter monsoon (EAWM). The long-term trend of boreal coniferous pollen concentration was similar to that of benthic δ18O. This orbital scale boreal conifer pollen assemblage variation indicates Quaternary EAWM evolution controlled by changes in global ice volume and climatic cooling. The marine palynological data reflect the ocean circulation history of the study area, where sea level fluctuations and tectonic activity played important roles around the marginal sea. The abundance of warm-water dinoflagellate species after ca. 1.9 Ma, including Tuberculodinium vancampoae , indicates Tsushima Warm Current intrusion related to the expansion of the Korea (Tsushima) Strait. Nematosphaeropsis labyrinthus and other cold-water species increased markedly during the MPT, suggesting a low sea surface temperature and weakened vertical mixing of the East Sea due to the cooled climate and sea ice during the MPT. The marked sea level fluctuation associated with the glacial–interglacial cycling after the MBE resulted in an assemblage composition shift from cold to warm water species. Tsuga and Betula thrived during mild winters, primarily influenced by winter insolation. These genera were particularly prosperous in the early Pleistocene, coinciding with a strong intrusion of the Tsushima Warm Current (TWC). Our findings should be considered in developing a comprehensive understanding of the paleoclimate and paleoceanographic history of northern East Asia across the major climate transitions of the Pleistocene. • Palynological records of Site U1430 reflect paleoenvironmental history over the 2 Ma. • Pollen records imply insolation forced paleotemperature changes prior to the MPT. • Boreal conifer pollen records indicate that the EAWM intensified at ca. 1.3 Ma. • Intrusion of the TWC intensified following the expansion of the KS at ca. 1.9 Ma. • Our results allow a direct comparison between climate-vegetation-marine conditions. [ABSTRACT FROM AUTHOR]

The Last Glacial Maximum (LGM; ∼26–18 kyr ago) is a time interval of great climatic interest characterized by substantial global cooling driven by radiative forcings and feedbacks associated with orbital changes, lower atmospheric CO2, and large ice sheets. However, reliable proxies of continental paleotemperatures are scarce and often qualitative, which has limited our understanding of the spatial structure of past climate changes. Here, we present a quantitative noble gas temperature (NGT) record of the last ∼40 kyr from the Albian aquifer in Eastern Paris Basin (France, ∼48°N). Our NGT data indicate that the mean annual surface temperature was ∼5 °C during the Marine Isotope Stage 3 (MIS3; ∼40–30 kyr ago), before cooling to ∼2 °C during the LGM, and warming to ∼11 °C in the Holocene, which closely matches modern ground surface temperatures in Eastern France. Combined with water stable isotope analyses, NGT data indicate δD/NGT and δ18O/NGT transfer functions of +1.6 ± 0.4‰/°C and +0.18 ± 0.04‰/°C, respectively. Our noble-gas derived LGM cooling of ∼9 °C (relative to the Holocene) is consistent with previous studies of noble gas paleothermometry in European groundwaters but larger than the low-to-mid latitude estimate of 5.8 ± 0.6 °C derived from a compilation of noble gas records, which supports the notion that continental LGM cooling was more extreme at higher latitudes. While an LGM cooling of ∼9 °C in Eastern France appears compatible with recent data assimilation studies, this value is greater than most estimates from current-generation climate model simulations of the LGM. Comparing our estimate for the temperature in Eastern France during MIS3 (6.4 ± 0.5 °C) with GCM outputs presents a promising avenue to further evaluate climate model simulations and constrain European climate evolution over the last glacial cycle. • A ∼40 kyr-long noble gas temperature (NGT) record in Western Europe (Paris Basin). • Observed NGTs yield a Last Glacial Maximum (LGM) cooling of −9.1 ± 0.9 °C (∼25 kyr ago). • Average cooling during the Marine Isotope Stage 3 was −5.1 ± 0.5 °C. • Most PMIP4 GCM models give smaller LGM cooling (lower climate sensitivity) than NGT. • δD and δ18O correlate with NGT, yielding +1.6 ± 0.4‰ and +0.18 ± 0.04‰/°C, respectively. [ABSTRACT FROM AUTHOR]

Fire provides an important indicator of paleoclimatic change. However, little information relating to late Cenozoic fire history has been gathered in mid-latitude Asia (including Inner Asia and East Asia), a key region for understanding the development of the arid-monsoon climate system as well as the driving forces behind it. Here we first report the records of microcharcoal concentrations (MC) covering the Holocene (10–0 ka) and late Pleistocene (0.8–0 Ma), which we use to analyze the fire activity patterns at an orbital time scale; then we compile the late Cenozoic MC record to investigate the long-term fire history by analyzing four cores from the Yangtze River Delta (YRD) area, East Asia (representing 8–0 Ma) and three sites in Inner Asia (representing 18–2 Ma). The results show that the (i) MC remained higher during the relatively dry late Holocene/glacial stages than that during the humid middle Holocene/interglacial stages at individual sites; (ii) MC increased with time in both Inner Asia and East Asia after 18 and 8 Ma, respectively; and (iii) MC always remained higher in the dry Inner Asia than in the contemporaneous wet East Asia. All these characteristics imply that late Cenozoic fire occurrence in mid-latitude Asia experienced a gradual increasing trend along with the global temperature/ice volume change, and indicates a continuous aridification trend across mid-latitude Asia. The global cooling, rather than the Tibetan Plateau uplift, might have played a key role in this observed trend. [ABSTRACT FROM AUTHOR]

The impact of the uplifted Tibetan Plateau on the East Asian monsoon (EAM) evolution is not an uncontroversial topic. Disentangling complex paleoclimatic signals derived from solar insolation, global ice volume, and the rise of Tibetan Plateau in the EAM domain is challenging because of the paucity of continuous Quaternary sedimentary records shed from the Tibetan Plateau. The 260-m-thick Xining loess deposits in the northeastern Tibetan Plateau (NETP) with ultra-high average accumulation rate of ∼23 cm/ka during 0.2–1.3 Ma provide an excellent opportunity to delineate the long-term influence of the uplifted Tibetan Plateau on paleoclimatic variations in the western margin of the EAM. High-resolution grain size and mineral magnetic analyses for this unique record reveal a much more significant long-term increasing trend of the East Asian winter monsoon strength and aridification compared with those of typical loess records on the Chinese Loess Plateau, confirming that the uplifted Tibetan Plateau may play an important part in enhancing the EAM circulation and aridity of Asian interior under global cooling. It is further proposed that the negative correlation between physical erosion and chemical weathering in the NETP does not contradict the prevailing uplift-weathering hypothesis, but probably suggests a strong climate-silicate-weathering feedback in this tectonically active region. This result provides robust evidence that the existence of the NETP and adjacent topography exerts a profound impact on the irreversible intensification of Asian interior aridity. • High-resolution mineral magnetic and grain size record for the thickest loess in NETP. • A prominent long-term increasing trend of EAWM strength and aridity during 0.2–1.3 Ma. • NETP plays an important part in enhancing the EAM strength and Asian interior aridity. • The negative correlation between physical and chemical weathering in Asian interior. • Strong climate-silicate-weathering feedbacks in NETP facilitate irreversible cooling. [ABSTRACT FROM AUTHOR]

Reconstructing past variability of the Antarctic ice sheets is essential to understand their stability and to anticipate their contribution to sea level change as a result of future climate change. Recent studies have reported a significant decrease in thickness of the East Antarctic Ice Sheet (EAIS) during the last several million years. However, the geographical extent of this decrease and subsequent isostatic rebound remain uncertain. In this study, we reconstruct the magnitude and timing of ice sheet retreat at the Sør Rondane Mountains in Dronning Maud Land, East Antarctica, based on detailed geomorphological survey, cosmogenic exposure dating, and glacial isostatic adjustment modeling. Three distinct deglaciation phases are identified for this sector during the Quaternary, based on rock weathering and 10Be surface exposure data. We estimate that the ice sheet thinned by at least 500 m during the Pleistocene. This thinning is attributed to the reorganization of Southern Ocean circulation associated with global cooling into the Pleistocene, which reduced the transport of moisture from the Southern Ocean to the interior of EAIS. The data also show that since the Last Glacial Maximum the ice surface has lowered less than ca 50 m and that this lowering probably started after ca 14 ka. This suggests that the EAIS in Dronning Maud Land is unlikely to have been a major contributor to postglacial sea-level rise and Meltwater pulse 1A. [ABSTRACT FROM AUTHOR]

Abstract: The Atlantic Meridional Overturning Circulation (AMOC) is a key feature of the climate system. However, its role during climate change is still poorly constrained particularly during an Interglacial to Glacial climate transition and the associated global cooling. We present here the first reconstruction of the evolution of the vertical structure of the rate of the AMOC from the Last Interglaciation to the subsequent glaciation (128,000–60,000 years ago) based on sedimentary (231Pa/230Th) records. We show a deep AMOC during the interglacial warmth Marine Isotope Stage (MIS) 5.5 and a shallower glacial one during glacial MIS 4. The change between these two patterns occurred mostly during the glacial inception, i.e. the transition from MIS 5.5 to MIS 5.4. Our data show that AMOC was enhanced during this latter transition as a consequence of a large increase of the overturning rate of the Intermediate Waters, above 2500 m. We suggest that this AMOC pattern required a reinforced Gulf Stream-North Atlantic Current system that ultimately supported ice-sheet growth by providing heat and moisture to the Northern high latitudes. From MIS 5.4 to MIS 5.1, the AMOC was broadly continuous below 2000m and supported periods of ice-sheet growth. As a result, a glacial AMOC is triggered at the beginning of MIS 4 due to the extension of ice-sheet and the subsequent reorganization of deep-water formation. This study highlights the role of intermediate waters as a major player during climate change. [Copyright &y& Elsevier]

The chronological framework for Neanderthal occupation and demise across Europe continues to be debated. In particular, there is still uncertainty regarding the nature, timing and regional expressions of the Middle to Upper Palaeolithic transition associated with the disappearance of Neanderthals and the broader expansion of modern human populations in Europe around 42–40 thousand years ago (ka). The geographical and chronological distribution of Neanderthal populations also remains difficult to evaluate owing to the practical challenges of directly dating human fossils at many sites, and the fact that a large proportion of Neanderthals sites lie close to, or well-beyond, the limits of radiocarbon dating. Cova del Gegant – one of the few sites in north-eastern Iberian Peninsula to yield Neanderthal fossil remains, associated Mousterian archaeological layers, and occupations related to the Middle and Upper Palaeolithic transition – is a key locality for informing these ongoing debates. Here we provide a comprehensive chronological framework for the Cova del Gegant site using multiple radiometric dating techniques (uranium-thorium (U–Th), radiocarbon and luminescence dating), sedimentological and micromorphological analyses, and Bayesian modelling. This integrated chronostratigraphic approach enables us to reliably reconstruct site formation processes and history, and undertake improved correlations with other sites regionally. The results allow us to sub-divide the Cova del Gegant sequence into three sections spanning ∼94 ka to ∼32 ka, namely: a Middle Palaeolithic sequence covering ∼94–59 ka, a Châtelperronian/Aurignacian section spanning ∼43–39 ka, and a Late Aurignacian/Gravettian section spanning ∼34–32 ka. The Neanderthal fossil remains accumulated in the cave between the end of Marine Isotope Stage (MIS) 5/MIS 4 and the beginning of MIS 3, during two different events dated to ∼72–67 ka and ∼60–52 ka. The chronological framework for Cova del Gegant is in accordance with that reported for other Middle and Upper Palaeolithic sites in north-eastern Iberian Peninsula, and reveals a record of successive human occupation coinciding with a period of progressive global cooling and lowering sea levels (end of MIS 5 through to MIS 2). Sedimentological evidence points to the emergence of a coastal platform in front of the cave and indicates that local palaeoenvironmental conditions likely benefited human displacements along the littoral margin, and favoured repeated occupation of the cave during the Late Pleistocene. • Middle–Upper Palaeolithic transition key to understanding Iberian human replacement. • Cova del Gegant is one of the few NE Iberian sites containing Neanderthal remains. • Chronostratigraphic model suggests three main occupations between 93 and 32 ka. • Sedimentological analysis points to emergence of a coastal platform during MIS 4–2. • Human displacement along littoral margin was important during the Upper Pleistocene. [ABSTRACT FROM AUTHOR]

The most recent maximum in global ice volume occurred around 23,000 to 19,000 years ago, during Marine Isotope Stage 2 (MIS 2; ∼29-14 ka) according to benthic δ18O and sea level records. However, evidence from cosmogenic surface exposure dating indicates that world-wide many glacier systems of different sizes as well as portions of some ice sheets were more extensive during MIS 4 (∼71-57 ka) and MIS 3 (∼57-29 ka) than they were during MIS 2. This discrepancy between global ice volume and ice extent must be explained in order to understand Earth's recent paleoclimate history. Here, we review MIS 4 moraine chronologies based on 10Be exposure dating, and we describe additional paleoclimate proxy records that indicate similar magnitudes of cooling during MIS 4 and MIS 2. While certain regions may have benefited from a wetter MIS 4 relative to MIS 2, it is unlikely that precipitation alone can explain more extensive glaciation on a global scale between 71 and 57 ka. Our review supports the hypothesis that the discrepancy between ice volume and ice extent during MIS 4 can be attributed to the growth of the North American ice sheets (and perhaps other northern ice sheets). Glaciers ultimately respond to changes in climate, however, large northern ice sheets also were affected by factors involving topography, isostacy, and glaciologic and mass balance dynamics. Given these feedbacks, the North American ice sheets' dominant role in global ice volume, sea level, and benthic δ18O signals might therefore result in a skewed picture of global climate. If maximum global ice volume during MIS 2 is mainly a function of North American ice sheet volume and not necessarily directly connected to global temperatures, then other records with extremes during MIS 2, such as dust and CO 2 , could be primarily reflecting ice volume change. • MIS 4 moraine chronologies in many locations suggest a possible collective advance of glaciers due to global cooling. • It is difficult to explain MIS 4 glacier extents if one assumes that global mean temperature followed a 'sawtooth' pattern. • Records displaying the 'sawtooth' pattern might be reflecting global ice volume rather than climate. • Obliquity causes symmetrical changes in insolation in both hemispheres and may still drive glacial climate. [ABSTRACT FROM AUTHOR]

The response of benthic foraminifera (BF) and radiolarian production in the central Okhotsk Sea (OS) to orbital and millennial changes of climate and environment over the last 136 kyr have been studied on the basis of the sediment core PC-7R, with available productivity, geochemical and lithological records and a modified age model. We used the calculated accumulation rate of microfossils (AR, fluxes) of the main ecological groups and species indicative of radiolarians and of BF as quantity responses in their production, which is related to environmental and hydrological changes of the water column and surface sediment in the central OS and to global and regional climate changes. The responses of the opportunistic BF Alabaminella weddellensis and the suboxic group during the last 136 kyr were mostly related to changes in organic fluxes from the surface, sea ice cover and surface sediment oxygenation at both orbital and millennial time scales. The AR of radiolarians from the surface, dichothermal and mesopelagic groups significantly differed from the AR of BF. The AR has a maximum during the middle and late Marine Isotope Stage 5e and lower values during the earlier Holocene, while the minimum happened during cold Marine Isotope Stages 6, 4 and 2 with maximal ventilation of OS intermediate water. Production of the mesopelagic radiolarian Cycladophora davisiana in the OS was mostly related to the lateral delivery of terrigenous material and OM into the water column from the northwestern shelf and/or from the western subarctic Pacific. Due to the sensitivity of marine organisms to environmental conditions, the production of radiolarians and BF sharply changed with the extinction of Amphimelissa setosa, since Heinrich Stadial 8 is related to the termination of global environment cooling and the hydrology changes of the early last glacial. • Benthic foraminifera and radiolarian responses in Okhotsk Sea to orbital and millennial climate changes over last 136 kyr. • Production of benthic foraminifera mainly changes in response to autochthonous organic fluxes to floor and sea ice cover. • Production of surface, dichothermal radiolarian and Amphimelissa setosa varied broadly synchronously with productivity. • Production of C. davisiana was responded to organic transport from subarctic western Pacific and northwestern Okhotsk Sea. • HS 8 in the Okhotsk Sea denotes the termination of the Northern Hemisphere climate cooling with extinction of A. setosa. [ABSTRACT FROM AUTHOR]

The regional paleoenvironmental record of Tokyo, central Japan, is required to enrich our understanding of climate change in East Asia and its impact on Japanese civilizations. Previous studies have generated paleotemperature records based on the analysis of shell mounds along the coast of Tokyo Bay and pollen from terrestrial borehole cores. However, a continuous, high time-resolution, quantitative paleotemperature record does not exist. A piston core was recovered from Tokyo Bay from which 22 mollusk shells were extracted. An age model for the core, determined via accelerator mass spectroscopy (AMS) 14C dating of the shells and a scoria layer from the Hoei eruption (1707 CE), showed that the core contains continuous record from ca. 2400 BCE. We analyzed the alkenone unsaturation ratios (UK' 37) to reconstruct the variations in the paleotemperature. The temperature during the Meghalayan was generally warmer than that at present exhibiting a declining trend, which roughly matches the changes in the orbital-forcing summer insolation and the millennial-scale latitudinal shift of the subarctic front in the northeastern Pacific Ocean. The largest cold period, which occurred ca. 2300 BCE and had a minimum temperature of 19.5 °C, interrupted the warm conditions. This cold period may correspond to the global cooling/drying "4.2 ka BP event," which marks the boundary between the Northgrippian and Meghalayan. Our results also revealed that several cold periods occurred, which may have been caused by decreases in solar activity or large volcanic eruptions. Particularly, large decadal to centennial-scale cold periods were observed ca. 440 BCE and 100 CE during the Yayoi era (ca. 900 BCE–300 CE). The coldest period after the establishment of a centralized system of government (ca. 300 CE–present) was recorded ca. 1050 CE, which may have been caused by the combination of a strong El-Niño mode and reduced solar activity. These climate change events can all be linked and, therefore, may be the potential causes of significant periods of famine and civil war in Japanese history, which eventually led to major shifts in Japanese social systems. • A well dated marine sedimentary core provided paleotemperature records of Tokyo. • The direct evidence of a sharp temperature drop around 4.2 ka BP was detected. • The decreases in solar activity and large volcanic eruptions caused the repeated cold climates. • The cold climates seem to coincide with the timing of social unrest in Japan. [ABSTRACT FROM AUTHOR]

Several studies have highlighted the importance of collecting well-dated records of palaeoenvironmental changes on desert margins, particularly in the semi-arid interior of southern Africa. Here we describe sediments at three sites in Kathu Pan, a pan complex overlying karstic bedrock at the southern edge of the Kalahari Basin. Sinkholes have exposed sedimentary sequences dating back to the Pleistocene, making it possible to document multiple palaeoenvironmental regimes in this landscape. Using a multi-analytical sedimentological approach, including micromorphology, energy dispersive X-ray spectrometry, electron microprobe, loss-on-ignition, laser diffractometry and luminescence dating, we demonstrate that the sediments at Kathu Pan represent an environment fluctuating among a number of thresholds for accumulation of different kinds of transported and authigenic sediments. Within the Pleistocene sands at the base of our studied sedimentary sequence, the presence of palygorskite, indicative of less extreme evaporative control, represents a semi-arid environment from 156 ± 11 ka to 32 ± 2 ka (Marine Isotope Stages 6–3). Increased moisture availability at 84 ± 4 ka and at 96 ± 5 ka (possibly during Marine Isotope Stages 5a and 5c, respectively) is reflected in the sands by the formation of palygorskite in concert with the deposition and oxidation of organic material. As the climate became increasingly arid, possibly in response to global cooling during the Last Glacial Maximum (21 ± 2 ka), Kathu Pan crossed a threshold, and deposition of CaCO 3 dominated over that of palygorskite. In the Holocene beds within our studied unit, alternating CaCO 3 - and organic-dominated deposits, sometimes in very fine laminae, reflect an increase in the amplitude of either seasonal or annual changes in water availability. • Palaeoenvironmental changes were reconstructed using sedimentological techniques. • Micromorphological evidence indicates a dry LGM and wetter conditions in MIS 5a & c. • Kathu Pan remained in a semi-arid climate with variable moisture availability. • Small pans are useful archives of regional palaeoenvironmental change in the Kalahari. [ABSTRACT FROM AUTHOR]

The South China Sea (SCS) is connected to the West Pacific through a deep channel in the Luzon Strait. Thus the SCS deep water is sensitive to the evolution of Pacific Ocean circulation, which significantly influences the global climate system. Geochemical data (Pb isotope and redox-sensitive elements data) and magnetic data were determined for a Fe–Mn nodule obtained from Jiaolong seamount in the central SCS. These records reflect interactions between changes in ice sheets, deep Pacific circulation, and weathering inputs to the deep SCS during the Pliocene and Quaternary. Our results show that the SCS deep-water environment can be divided into three major Stages (Stages 1–3). Stage 1 (∼4.8–1.4 Ma) was characterized by a well-oxygenated Pacific Deep Water (PDW) and lower dust inputs; then moderate stable deep-water ventilation and greater inputs of Asian dust occurred during Stage 2 (1.4–0.9 Ma). During Stage 3 (<0.9 Ma), a more isolated PDW was accompanied by sluggish Pacific overturning circulation, probably due to the weakened southern-sourced deep-water formation. In general, the progressive intensification of northern hemisphere ice-sheet play an active role in controlling the variation of the deep-water environment in the SCS. Interestingly, the variation in deep-water ventilation lagged behind weathering and erosion around the Middle Pleistocene Transition, which strongly indicates that the ocean and continent environments had different sensitivities to the global paleoclimatic changes at the glacial climate boundary. [ABSTRACT FROM AUTHOR]

Formed in the Southern Ocean, Antarctic Intermediate Water (AAIW) plays a fundamental role in the modern climate system as an important sink for atmospheric CO 2 , and as a mid-depth conduit supplying nutrient-rich waters to subtropical and tropical upwelling regions. During the transition from warm Pliocene 'greenhouse' conditions to Pleistocene 'icehouse' conditions around 3 Ma, model simulations suggest dramatic circulation changes in the Southern Ocean AAIW formation region due to cooling and expanded sea ice cover around Antarctica. However, the history and properties of AAIW over this time period are still poorly understood. Here, we trace AAIW source water provenance, temperature, and salinity changes over the last 4 Myr using Nd isotopes of Fe-Mn-oxyhydroxide encrusted foraminifera, benthic foraminiferal Mg/Ca, and stable isotopes from southwest Atlantic DSDP Site 516. Our results show that modern AAIW properties emerged gradually over the last 3 Myr, as evidenced by gradual cooling (6 °C) and freshening of intermediate waters. Over this same interval, εNd-values decrease and diverge away from those of Pacific-sourced waters and converge on values of present-day Circumpolar Deep Water (CDW). These observations are in accordance with model simulations indicating increased deep vertical mixing at the Polar Front associated with sea ice extension. These modified AAIW source waters penetrated increasingly northward into the Atlantic at intermediate depths, enhancing nutrient supply and contributing to surface cooling along subtropical coastal upwelling sites. These circulation changes may have facilitated ocean CO 2 storage, providing a positive feedback amplifying global cooling and intensification of Northern Hemisphere Glaciation. • Multi-proxy records from Site 516 (AAIW depths) during the Plio/Pleistocene. • During 3-0 Ma foraminiferal Nd isotopes decrease and merge towards a Circumpolar Deep Water source. • During the Quaternary benthic foraminiferal Mg/Ca derived temperatures/salinities cool and freshen by 8 °C. [ABSTRACT FROM AUTHOR]

Knowledge of variations of the sedimentary sources of the proximal deserts of the Chinese Loess Plateau (CLP) is important for understanding eolian processes linking environmental changes within provenance areas and the areas of deposition downwind. In addition, it may shed light on the history of the uplift of the Tibetan Plateau. However, the long-term variations in provenance of the proximal deserts of the CLP are still unknown. The Tengger Desert (TD) is one of the proximal deserts upwind of the CLP. It is located in a depression (also a plateau) on the northeastern margin of the Northern Tibetan Plateau (NTP) and to the south of the Gobi Altay Mountains (GAMs). Here, we present U-Pb age spectra of detrital zircon grains from 11 sand layers from core BJ14 which was drilled in the northwestern part of the TD. The ages of the sand layers range from 2.35 to 0.11 Ma. The results indicate that: (1) The GAMs and NTP were two competing provenance areas of sands in the TD. (2) The dominant provenance area of clastic materials in the TD area was GAMs during 2.35–1.80 and 1.2–0.6 Ma, and the NTP at ∼1.56 Ma and during 0.36–0.11 Ma. The shift in the dominant provenance area in the TD from the GAMs to the NTP was controlled by the phased uplift of the Tibetan Plateau against the background of global cooling. (3) The relative increase of the sedimentary contribution from the NTP was generally synchronous with increases in the accumulation rate and the enlargement of eolian sand/dust deposits downwind, but the increase began at a late stage in the phased uplift of the Tibetan Plateau. These findings indicate that the phased rapid uplift of the NTP was a trigger which dominated the variations in the provenance of the proximal deserts of the CLP and beyond. • The GAMs and NTP were two competing provenance areas of sand in the TD since 2.35 Ma. • Change of dominant provenance from GAMs to NTP was controlled by phased uplift of NTP at a background of global cooling. • The uplift of the NTP was a trigger in variations of provenance of the proximal deserts of the CLP. [ABSTRACT FROM AUTHOR]

Ilopango volcano (El Salvador) erupted violently during the Maya Classic Period (250–900 CE) in a densely-populated and intensively-cultivated region of the southern Maya realm, causing regional abandonment of an area covering more than 20,000 km2. However, neither the regional nor global impacts of the Tierra Blanca Joven (TBJ) eruption in Mesoamerica have been well appraised due to limitations in available volcanological, chronological, and archaeological observations. Here we present new evidence of the age, magnitude and sulfur release of the TBJ eruption, establishing it as one of the two hitherto unidentified volcanic triggers of a period of stratospheric aerosol loading that profoundly impacted Northern Hemisphere climate and society between circa 536 and 550 CE. Our chronology is derived from 100 new radiocarbon measurements performed on three subfossil tree trunks enveloped in proximal TBJ pyroclastic deposits. We also reassess the eruption magnitude using terrestrial (El Salvador, Guatemala, Honduras) and near-shore marine TBJ tephra deposit thickness measurements. Together, our new constraints on the age, eruption size (43.6 km3 Dense Rock Equivalent of magma, magnitude = 7.0) and sulfur yield (∼9–90 Tg), along with Ilopango's latitude (13.7° N), squarely frame the TBJ as the major climate-forcing eruption of 539 or 540 CE identified in bipolar ice cores and sourced to the tropics. In addition to deepening appreciation of the TBJ eruption's impacts in Mesoamerica, linking it to the major Northern Hemisphere climatic downturn of the mid-6th century CE offers another piece in the puzzle of understanding Eurasian history of the period. Image 1 • Major eruption of Ilopango volcano, El Salvador occurred in the first half of the 6th century. • Ilopango eruption is consistent with 'mystery' eruption of 540 CE that caused global cooling. • Magnitude 7 event ranks as one of the 10 largest on Earth in past 7000 years. • Impacts on the Maya of Central America were severe, including estimated 100,000 + fatalities. [ABSTRACT FROM AUTHOR]