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Large paleochannels with sizes far greater than the modern ones are widespread on the floodplains and low terraces of rivers in the Volga basin. These are indicators of higher values of river runoff in the end of the latest glacial epoch. The assessment of the time interval of the epoch of abundant runoff requires the determination of the age of large paleochannels. With this in view, drilling of large paleochannels has been carried out all over the Volga basin. Radiocarbon dating of the channel alluvium was carried out. The majority of dates lied within the time interval 14.5–17.0 thousand years ago, which suggests the conclusion that the epoch of abundant river flow approximately coincides in time with the early Khvalynian transgression of the Caspian Sea. [ABSTRACT FROM AUTHOR]

Determining how gas hydrate distribution evolved along continental margins in the past is essential to understanding its evolution in the future. Moreover, hydrate decomposition has been linked to several catastrophic events, including some of the largest submarine landslides on Earth and the massive release of greenhouse gases into the ocean. Offshore Romania, the presence of a second bottom‐simulating reflector (BSR) provides an opportunity to gain valuable insights into hydrate dynamics since the Last Glacial Period (LGP). We conducted transient modeling of hydrate thermodynamic stability by merging in‐situ observations with indirect assessments of sea‐bottom temperature, thermal conductivity, salinity, sedimentation rate, and sea‐level variations. We reveal a strong correlation between the BSRs and the base of the Gas Hydrate Stability Zone (GHSZ) during both the present and LGP periods. The gradual evolution of the GHSZ over the past 34 ka presented here supports a conceptual model that excludes catastrophic environmental scenarios. Plain Language Summary: Methane hydrate is an ice‐like compound composed of a cage of water molecules enclosing a methane molecule. Hydrates can form in marine sediments along continental margins where water and methane are present under high pressure and low temperatures. As a result of climate change, hydrate melting has been linked to catastrophic events, including submarine landslides and the release of greenhouse gases into the ocean. Offshore Romania, the presence of a relic of the base of the hydrate layers formed in sediments during past glacial conditions, reveals the evolution of the hydrate stability zone since the last glacial period. The 2D modeling results have enabled us to define the area where hydrates alternately melt and reform in response to environmental changes such as rising temperatures and sea levels. Our results show that the evolution of gas‐hydrate accumulations generates multiple, slow chain reactions, preventing the system from disastrous destabilization, sequentially provoking catastrophic events. Key Points: A 2D modeling reveals the observed deeper secondary BSR is mostly consistent with a paleo‐BSR developed during the last glacial periodA paleo‐BSR can only be preserved in sediments if the period of stagnation of the base of hydrate layers is sufficient to trap enough gasAlthough rapid environmental changes, the hydrate‐free gas system reacts much more slowly preventing catastrophic submarine destabilization [ABSTRACT FROM AUTHOR]

[Objective] The Upper Pleistocene eolian loess accumulation in islands of the East China Sea is an important expansion for loess in China in the eastern Yangtze River delta and its extended sea area. The better study of the eolian loess provenance and its evolution in this region is particularly important for understanding regional paleoenvironmental changes. [Methods] Based on the analyses of optically stimulated luminescence (OSL) dating and magnetic susceptibility, parametric end-member analysis was used to clarify the grain size data for Shengshan Island loess and its paleoenvironmental effect. [Results and Conclusions] Three end-members (EM1-EM3) were identified: EM1 is the clay component transported by the westerly circulation; EM2 is the fine silt component trans-ported over long distances, suspended in the form of floating dust that was deposited when the wind force weakened; and EM3 is the coarse silt component carried by winter winds for short distances and deposited near the land surface. It was inferred from the analysis that EM1 and EM2 were the main sources of dust in the loess profile on Shengshan Island. Combined with the optically stimulated luminescence (OSL) results, the variations of frequency susceptibility, median particle size, Rb/Sr values and the fluctuations of the end-members in the loess profile revealed that the Shengshan Island loess accumulated in marine isotope stage MIS2 experienced paleoclimatic fluctuations from warm and humid to cold and dry, and then to warm and humid in MIS3. The end-member properties also responded to the paleoenvironmental changes during the last glacial maximum and deglaciation period of the MIS2 stage. Climatic fluctuations recorded by the loess deposits also correspond to the trends of deep-sea oxygen isotopes and ancient sea-level changes. Thus the environmental evolution in the shelf areas of the East China Sea were closely related to global paleoclimatic variations. [ABSTRACT FROM AUTHOR]

Abstract Determining how gas hydrate distribution evolved along continental margins in the past is essential to understanding its evolution in the future. Moreover, hydrate decomposition has been linked to several catastrophic events, including some of the largest submarine landslides on Earth and the massive release of greenhouse gases into the ocean. Offshore Romania, the presence of a second bottom‐simulating reflector (BSR) provides an opportunity to gain valuable insights into hydrate dynamics since the Last Glacial Period (LGP). We conducted transient modeling of hydrate thermodynamic stability by merging in‐situ observations with indirect assessments of sea‐bottom temperature, thermal conductivity, salinity, sedimentation rate, and sea‐level variations. We reveal a strong correlation between the BSRs and the base of the Gas Hydrate Stability Zone (GHSZ) during both the present and LGP periods. The gradual evolution of the GHSZ over the past 34 ka presented here supports a conceptual model that excludes catastrophic environmental scenarios.

The White River Badlands (WRB) of South Dakota record eolian activity spanning the late Pleistocene through the latest Holocene (21 ka to modern), reflecting the effects of the last glacial period and Holocene climate fluctuations (Holocene Thermal Maximum, Medieval Climate Anomaly, and Little Ice Age). The WRB dune fields are important paleoclimate indicators in an area of the Great Plains with few climate proxies. The goal of this study is to use 1 m/pixel-resolution digital elevation models from drone imagery to distinguish Early to Middle Holocene parabolic dunes from Late Holocene parabolic dunes. Results indicate that relative ages of dunes are distinguished by slope and roughness (terrain ruggedness index). Morphological differences are attributed to postdepositional wind erosion, soil formation, and mass wasting. Early to Middle Holocene and Late Holocene paleowind directions, 324°± 13.1° (N = 7) and 323° ± 3.0° (N = 19), respectively, are similar to the modern wind regime. Results suggest significant landscape resilience to wind erosion, which resulted in preservation of a mosaic of Early and Late Holocene parabolic dunes. Quantification of dune characteristics will help refine the chronology of eolian activity in the WRB, provide insight into drought-driven landscape evolution, and integrate WRB eolian activity in a regional paleoenvironmental context. [ABSTRACT FROM AUTHOR]

Biological pump processes generated by diatom production in the surface water of the Southern Ocean play an important role in exchanging CO2 gas between the atmosphere and ocean. In this study, the biogenic opal content of the sediments was measured to elucidate the variation in the primary production of diatoms in the surface water of the Southern Ocean since the last glacial period. A piston core (COR-1bPC) was collected from the Conrad Rise, which is located in the Indian sector of the Southern Ocean. The sediments were mainly composed of siliceous ooze, and sediment lightness increased and magnetic susceptibility decreased in an upward direction. The biogenic opal content was low (38.9%) during the last glacial period and high (73.4%) during the Holocene, showing a similar variation to that of Antarctic ice core ΔT and CO2 concentration. In addition, the variation of biogenic opal content in core COR-1bPC is consistent with previous results reported in the Antarctic Zone, south of the Antarctic Polar Front, in the Southern Ocean. The glacial-interglacial biogenic opal production was influenced by the extent of sea ice coverage and degree of water column stability. During the last glacial period, the diatom production was reduced due to the penetration of light being limited in the euphotic zone by the extended sea ice coverage caused by the lowered seawater temperature. In addition, the formation of a strong thermocline in more extensive areas of sea ice coverage led to stronger water column stability, resulting in reduced diatom production due to the reduction in the supply of nutrient-rich subsurface water caused by a decrease in upwelling intensity. Under such environmental circumstances, diatom productivity decreased in the Antarctic Zone during the last glacial period, but the biogenic opal content increased rapidly under warming conditions with the onset of deglaciation. [ABSTRACT FROM AUTHOR]

Studies with climate model data, which is one of the methods used to understand the climatic conditions of the past, are increasing, while the studies of balancing and validating which of these studies better demonstrate the reality remain more limited. In this study, glacier areas in the Holdridge biomes were produced from the datasets of 7 different climate model escapades with enhanced resolution, and these areas were compared with the paleo glacier areas in Turkey. In the study, 1 km resolution data sets were used, and the similarities and differences between the glacier and cold desert areas obtained and Turkey's Last Glacial Maximum glacier areas produced using different sources were evaluated. For the evaluation, Turkey's paleo glacier areas were divided into regions, thus it was revealed which climate model gave less inaccurate results in which region. As a result, it was seen that the MPI-ESM-P and CCSM4 models gave consistent results for larger areas in Turkey, while the FGOALS2, IPSL-CM5A-LR, MRI-CGCM3 models gave significant results on a regional basis. On the other hand, it has been revealed that MICRO-ESM and CNRM-CM5 models need to be improved in order to represent the LGM climate conditions in Turkey.

Taxonomic decisions made by palaeontologists are often based on a few morphological features preserved in the fossil material. This practice may sometimes lead to the description of new species based on single specimens, which are, in fact, extreme or aberrant morphological variants of known taxa. Ancient DNA (aDNA) analysis of the Late Pleistocene specimens from the archaeological site Petits Guinards (Creuzier-la-Vieux, Allier, France), described as a new vole Microtus (Sumeriomys) bifrons, did not confirm the species distinctness of the studied population. The genetically examined specimens belonged to Stenocranius anglicus and/or Microtus arvalis, the dominant species at the site. Our findings show that it is risky to describe new fossil taxa on the basis of phenotypic outliers or morphologically aberrant, rare specimens that do not fall within the previously known population variability. We also highlight the importance of ancient DNA in resolving taxonomic and nomenclature problems and classifying fossil mammals of the Late Pleistocene age. [ABSTRACT FROM AUTHOR]

Paleoclimate changes during the last glacial in the arid central Asia are not as well understood as the monsoon-dominated areas of Asia. Here we report a 75-m-long sediment core over past 120 kyr based on astronomical tuning combined with the optically stimulated luminescence (OSL) dating in the Kashi depression of the western Tarim Basin, Northwest China. Analysis of grain size and highresolution gamma ray (GR) logs from the KT11 borehole across the last glacial period yields a climate history for the Tarim Basin which reflects the variations of its temperature and the hydrological cycles. Comparison of these records with north hemisphere summer insolation, the Greenland ice core temperature, stalagmites and the loess from the nearby region indicates that the deposits in the fluvio-lacustrine system of the Kashi depression responded to climate change at the Younger Dryas (YD), six Heinrich cooling events and the Dansgaard-Oeschger cycles. Our work indicates that the alternations between warm-humid and cold-dry climates were prevalent in the western Tarim Basin during the last glacial period, showing an in-phase pattern with the climate variations of the East Asian Monsoon, controlled ultimately by precession and North Atlantic Ocean climate variability on orbital-millennial time scales. [ABSTRACT FROM AUTHOR]

Clues of climate change on the Alashan Plateau since the last glacial period (40 ka) are important for revealing the mechanism of desertification of middle-latitude deserts in the Northern Hemisphere (NH). Studies are still rare for the understanding of the specific relationship of climate changes between the Alashan Plateau and the global. Based on a systematic and comparative analysis of the existing research in China and the international academic community, this paper reviews the environmental evolution history of the Alashan Plateau since the last glacial period from the records of paleo-environment and geomorphological characteristics in different deserts of the plateau (e.g., Badanjilin, Tenggeli, and Wulanbuhe). From about 40 ka to the end of the last glacial maximum, the climate on the plateau was wetter than it is today, and to the end of the Pleistocene, the climate was generally dry and the aeolian activities were enhanced. However, the climate was arid during the whole last glacial period in the Wulanbuhe Desert, evidently different from the overall pattern of the plateau. The Tenggeli Desert was characterized by an arid climate in the early Holocene. The most controversial events for the Alashan Plateau are the drought events in the middle Holocene in the Badanjilin Desert. The role and impact of the westerlies and the East Asian Summer Monsoon (EASM) systems on the climate change of the desert and even the whole plateau is a vexed question that brings different views in different periods. There is still a lack of definite evidence representing the events of global environmental change that occurred on the plateau during the discussed period. The distinctive morphology of dune mountains and the distribution of sand dunes are mutually indicative of the direction and energy of wind systems on the plateau. It is suggested that appropriate wind energy is the significant key to the desertification in these middle-latitude deserts on the plateau. From a global-scale review of climate change, the desertification of the modern-scale sandy desert landscapes on the Alashan Plateau is generally related to the global glacial period and the cold and dry climate during the past 40 ka. [ABSTRACT FROM AUTHOR]

Discussing the development and shrinkage process of glaciers is of great significance for the in–depth comprehension of regional environmental evolution and predicting global changes. However, there is little understanding of the developmental and retreat processes of mountain glaciers during the Late Quaternary (150 ka) in the East Asian Monsoon region. Using the latest chronological glacial data from eastern China, Taiwan, the Russian Far East, and the Japanese islands of Hokkaido and Honshu, which are all regions impacted by the East Asian Monsoon, we screened reliable glacial age data. This study compiled and compared the age sequences of the different mountain glaciations (dating techniques included optically–stimulated luminescence (OSL), thermoluminescence (TL), electron spin resonance (ESR), U–series (U), cosmogenic nuclides (10Be/CRN), carbon–14 (14C) and potassium–argon (K–Ar), etc.). Based on the evolutionary features of the glaciations in these mountains, by comparison with the marine isotope stage (MIS) environment, the influence of monsoonal circulation patterns on the regional development of glaciers was analyzed. This study determined that Japanese mountain glacial stages since 150 ka are the most complete in the East Asian Monsoon region, having developed during MIS 6–1. Taiwanese mountain glaciers developed during MIS 4–1, but glacial stages in continental East Asia were relatively short, with glaciers first developing only during MIS 3b–1. The reason for this this phenomenon is that the tectonic uplift in different subregions was significantly different; on the other hand, it is also related to the difference of precipitation between land and sea in monsoon climate. By comparing the glacial glaciations in the East Asian Monsoon region with western China, we found that there were significant differences between the extent, onset time, and length of glacial periods. Since the Last Glacial Period, precipitation levels have become transitional and concentrated during the summer months, and temperatures have been continuously changing as a result of the many periodic changes in the East Asian Monsoon. From the Early Last Glacial Period (MIS 4) to the Middle Last Glacial Period (MIS 3b) to the Last Glacial Period (MIS 2/LGM–YD), climatic conditions increasingly restricted the development of glaciers; the regional environment continued to warm until glaciers completely disappeared during the Late Holocene. [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]

During the last glacial period, the tropical hydrological cycle exhibited large variability across orbital and millennial timescales. However, the response of the Indian summer monsoon (ISM), its related impact on terrestrial ecosystems, and associated forcing mechanisms remain controversial. Here we present a marine record of pollen‐inferred vegetation changes suggesting that eastern India shifted from woody‐savanna mosaics during Marine Isotopic Stage 3 to grasslands during the Last Glacial Maximum resulting from large‐scale drying. Our data shows that ISM maximum is in phase with obliquity and precession maxima suggesting a dominant role of the Indian Ocean interhemispheric temperature gradient on glacial ISM variability. Persistent and abrupt dryland expansions of varying magnitude suggest rapid‐scale onset of aridity during Heinrich Stadial events and during the Toba eruption. We propose that the amplitude of ISM drought events are initiated by high latitude and volcanic forcings, although modulated by precession. Plain Language Summary: Climatic mechanisms controlling variations in the monsoon rainfalls in India remain unclear even though there is a consensus on the strong vulnerability of this region to the ongoing climate change. Based on the reconstruction of the vegetation in eastern India during the last glacial, our study reveals that very low monsoon rainfall, as indicated by a drastic reduction in trees, occurred when the global ice volume reached its maximum by affecting the global and Indian wind circulations. Conversely, the moistest conditions, as reported by the development of a wooded savannah, are recorded during a period characterized by a specific insolation configuration, which reinforces the temperature contrast over the Indian ocean, and thus the humidity supplied to India. Intense droughts are also documented by the abrupt increases of arid vegetation in response to massive iceberg discharges in the North Atlantic and a major tropical volcanic eruption. We suggest that a low seasonal thermic contrast in the tropical region amplifies the dryness associated with these catastrophic events in India. Key Points: Savannah expansion records the highest glacial rainfall in response to an obliquity maximum strengthening of the interhemispheric gradientDuring the last glacial maximum, an open savannah shows low humidy related to large‐scale atmospheric reorganizationSevere droughts occurred in India during the Heinrich Stadials and in response to the Toba eruption, likely amplified by precession [ABSTRACT FROM AUTHOR]

Geranium erianthum is an alpine plant growing in dry habitats, which is distributed from East Asia to northern coastal regions of the northern Pacific. The ice-free area around the current Bering Strait (i.e., Beringia) had played an important role in range expansion into neighboring regions such as East Asia and North America for some alpine plants. However, recent studies suggest that some alpine plants in snowbed environment spread from East Asia to northern coastal regions of the northern Pacific. In this study, we investigated phylogenetic relationships and genetic differentiations among populations of G. erianthum and the related species using the chloroplast genome and single-nucleotide polymorphisms, to evaluate the alternative biogeographic hypotheses in which region of Beringia, British Columbia or East Asia is probable for its distributional origin. Range reconstruction based on phylogenetic tree of chloroplast genome indicated G. erianthum and related species originated in East Asia, from where G. erianthum migrated eastward into Beringia and British Columbia. In addition, nuclear genome-wide SNPs indicated that no significant genetic differentiation was detected between Japanese and Beringian populations. The lack of genetic differentiation suggests that the current range of G. erianthum resulted from rapid range expansion during the latter period of the last glacial era. Overall, the East Asian refugium hypothesis was applicable to the alpine plant G. erianthum in dry habitat, indicating that range expansion pattern from East Asia into the northern Pacific may be more common rather than limited for snowbed species. [ABSTRACT FROM AUTHOR]

Taxonomic decisions made by palaeontologists are often based on a few morphological features preserved in the fossil material. This practice may sometimes lead to the description of new species based on single specimens, which are, in fact, extreme or aberrant morphological variants of known taxa. Ancient DNA (aDNA) analysis of the Late Pleistocene specimens from the archaeological site Petits Guinards (Creuzier-la-Vieux, Allier, France), described as a new vole Microtus (Sumeriomys) bifrons, did not confirm the species distinctness of the studied population. The genetically examined specimens belonged to Stenocranius anglicus and/or Microtus arvalis, the dominant species at the site. Our findings show that it is risky to describe new fossil taxa on the basis of phenotypic outliers or morphologically aberrant, rare specimens that do not fall within the previously known population variability. We also highlight the importance of ancient DNA in resolving taxonomic and nomenclature problems and classifying fossil mammals of the Late Pleistocene age.

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Ice margin remains are of great significance for reconstructing climatic conditions in certain areas and time periods and in delineating permafrost boundaries. In the middle and upper reaches of the Qingshui River in Ningxia (36°22′5"N~36°25′53"N), a group of ice margin remnants of the highest glacial period of the last glacial period were found, including ancient ice wedges and thaw folds. Among them, 4 ancient ice wedges were found in the section of Tangbao Village, which were wedge-shaped in shape, wide above and narrow below; The wedge wall is not straight, and the fissures formed before the collapse of the strata around the wedge; The wedge is filled with fragments of the surrounding formation and brownish-red silt. Two layers of continuous thaw folds were found in the section of Sanchahe Village, and the axial surface of the folds tended to be productionally chaotic and had no uniform orientation; There is no significant thickening or thinning of the fold shaft, no interlayer sliding occurs in the wing part, and the top of the fold layer is not developed and truncated; Interlayer folds are not developed interstitial backflush or positive rupture. Dating and measuring according to photoreflection14C dating results showed that paleogyne wedges formed at 14.06-11.45 ka B.P. and thaw folds formed at 13 500-11 570 a B.P. Affected by the Neo-Nymph event, the Qingshui River Basin developed a large area of permafrost at the peak of the last glacial period, with a distribution range of at least 36°22′5"N south. Since the last glacial period of northern China, the western section of the southern boundary of the permafrost can be pushed southward at least about 52′ (radial distance of about 97 km). This finding provides new evidence for the demarcation of the southern boundary of permafrost in northern China during the last glacial period [ABSTRACT FROM AUTHOR]

Abstract In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ18O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ18O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ18O profile of this stalagmite may imply millennial-scale changes, and high δ18O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ18O values; the mean δ18O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ18O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ18O for the last glacial period in Fukugaguchi Cave most likely resulted from 18O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ18O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of 18O depletion in Japan Sea surface water during the last glacial period.

During the last deglaciation and middle Holocene, rapid climatic changes occurred repeatedly. Previous research has primarily focused on investigating these periods in East Asia's coastal and inland regions of the Eurasian continent. In contrast, a limited number of studies have reported on climate change and its environmental impacts in island areas near the Pacific Ocean. This study aims to reconstruct paleosol drainage conditions and lake water level fluctuations in the Suwa Basin, an inland basin in central Japan, after the last deglaciation. We utilize the identification of paleosols and the geochemistry of lacustrine sediments to discuss climate change and its impacts on terrestrial environments in the East Asian coastal region. During the Last Glacial Maximum, the basin experienced a lowstand period; meandering fluvial systems led to the development of dry and well-drained paleosols. The lacustrine environment expanded between ca. 16 cal kyr BP and 5 cal kyr BP during a transgressive period. Short-term lake-level fluctuations were reconstructed by examining repeated paleosol development and changes in the bulk SiO 2 content originating from biogenic silica in lacustrine sediments. Our data suggest that the lake's water level fell at ca. 12 cal kyr BP, 8 cal kyr BP, and 7 cal kyr BP. After 5 cal kyr BP, thin paleosols repeatedly formed during short exposure times due to the rapid sedimentation rate in the delta system, which corresponds to the highstand period. Short-term fluctuations between 16 kyr BP and 5 kyr BP, in the lake water level in the inland basin of the Japanese Islands was influenced by drying and cooling trends in the East Asian coastal region, as well as declines in sea surface temperatures in the western tropical Pacific Ocean. These fluctuations roughly synchronize with the Younger Dryas stadial and an 8.2 ka cooling event. Changes in precipitation, which responded to fluctuations in the East Asian summer monsoon intensity and tropical depressions, likely regulated the lake water level. These findings imply the predominant influence of paleoclimate fluctuations over thousands of years on the hydrological regime of lake systems across the island area of the East Asia. • Changes in lake water levels in central Japan in last 16 kyr were clarified. • 1000-yrs scale lake level changes occurred after the last deglaciation. • The lake level declines coincided with the Younger Dryas and an 8.2 ka event. • It shows effect of high latitude climate changes on lake systems in coastal East Asia. [ABSTRACT FROM AUTHOR]

Widely distributed wetlands in China play an important role in the global carbon cycle. However, the long-term response of wetland evolution and carbon storage in tropical southern China to climate change remains unclear. Here, we present a sediment core record from the Tiaoshu Wetland in the northern Leizhou Peninsula and multiple proxy indicators are investigated, with the aim of better understanding past vegetation and environmental changes. The following conclusions were drawn: (i) The organic matter deposited in the Tiaoshu Wetland was mainly derived from terrestrial C3 plants and aquatic plants growing in and/or around the catchment. The temporal variability in the relative proportions of organic matter contributed by various sources revealed paleoenvironmental changes in the study area, generally consistent with regional and global climate records. (ii) The peat formation pattern in the Tiaoshu Wetland is in contrast to some individual sites reported in subtropical China, suggesting that there may be different peat formation patterns in the tropical and subtropical regions of China, which may be closely related to specific hydrothermal conditions in different regions. In addition, by comparison with atmospheric CH 4 concentrations, our results suggest potential relationships between the evolution of wetlands in tropical China and global atmospheric CH 4 cycles. • Alternation between terrestrial and aquatic plants dominated the organic matter sources in the Tiaoshu Wetland. • Variations in organic matter sources reveal vegetation succession and a response to climate changes. • Peat formation patterns may differ between tropical and subtropical regions of China. [ABSTRACT FROM AUTHOR]

The recent geological history of the Northern Andes is characterized by the interaction of dynamic surface processes such as volcanic activity, fluvial erosion, mass movements, etc. that have shaped landscapes for millennia. Despite its great geological and biological importance, the long-term ecological history of middle-elevation tropical habitats (between 1000 and 2500 m.a.s.l.) is unknown, due to the scarcity of suitable paleo archives preserving the paleoecological signal, leading to a critical data gap. This manuscript reports well-preserved subfossil woods of the Pleistocene volcanoclastic deposits from the Central Cordillera of Colombia. Four wood specimens are described and identified as Terminalioxylon gumminae sp.nov., Andesanthus risaraldense sp.nov., Anacardium quindiuense sp.nov., and Chrysochlamys colombiana. This report demonstrates the potential of volcanic deposits in the Northern Andes as paleo archives, and contributes to the fossil record of the tropical Andes, as it contains elements of mid-altitude vegetation preserved in association with the Pleistocene volcanic activity of the Central Cordillera. The environments where these subfossil species lived resemble present environmental conditions. This is a baseline for future paleobotanical exploration and paleoenvironmental analyses. • We investigated four subfossil woods from the late Pleistocene of the Northern Andes. • Novel species of Anacardium, Andesanthus, and Terminalioxylon described. • One specimen was identified as Chrysochlamys colombiana. • This is a baseline for future paleobotanical and paleoenvironmental studies. [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]

To reconstruct the interaction between Antarctic Bottom Water (AABW) and global climate change, extracting information about past AABW formation from the sedimentary record is crucial. The Prydz Bay region, East Antarctica, has high glacier outflow and is a region of vigorous formation of AABW associated with sea ice formation. The Cape Darnley Bottom Water (CDBW), a primary AABW precursor, flows into Wild Canyon west of Prydz Bay. Thus, the sedimentary record of Wild Canyon can serve as an archive for CDBW flow. In this study, to identify the sedimentary processes and mineral compositions characteristic of CDBW flow, we evaluate deep-sea camera imagery, X-ray computed tomography images, grain-size data, and optical and chemical mineralogical analyses. Heavy minerals in the surface sediments are characterized by pyrope-rich almandine garnets (up to 80% of the heavy-mineral assemblage, 0.2%–3.7% of the dry bulk sediment by weight) typical of nearshore sediment derived from Mac. Robertson Land. In addition, ripples on the channel floor indicate sediment transport occurred as tractional bedload, whereas settling of suspended sediment prevailed on the canyon levee. We propose that modern CDBW flow is the dominant process of sediment reworking through sustained high flow velocities, distinctly different from turbidity currents triggered by ice sheet expansion and rapid retreat. Our results further suggest that fine-grained sediments are transported to the canyon levee as CDBW flows through the submarine canyon. These findings will be a key for reconstructing past AABW formation, which is crucial for understanding the response of AABW to future climate change. • Ripples formed by Cape Darnley Bottom Water are identified in Wild Canyon. • Antarctic Bottom Water flow triggers the reworking of pre-existing sediments. • Sedimentary processes are different during AABW active/inactive periods. [ABSTRACT FROM AUTHOR]

Clues of climate change on the Alashan Plateau since the last glacial period (40 ka) are important for revealing the mechanism of desertification of middle-latitude deserts in the Northern Hemisphere (NH). Studies are still rare for the understanding of the specific relationship of climate changes between the Alashan Plateau and the global. Based on a systematic and comparative analysis of the existing research in China and the international academic community, this paper reviews the environmental evolution history of the Alashan Plateau since the last glacial period from the records of paleo-environment and geomorphological characteristics in different deserts of the plateau (e.g., Badanjilin, Tenggeli, and Wulanbuhe). From about 40 ka to the end of the last glacial maximum, the climate on the plateau was wetter than it is today, and to the end of the Pleistocene, the climate was generally dry and the aeolian activities were enhanced. However, the climate was arid during the whole last glacial period in the Wulanbuhe Desert, evidently different from the overall pattern of the plateau. The Tenggeli Desert was characterized by an arid climate in the early Holocene. The most controversial events for the Alashan Plateau are the drought events in the middle Holocene in the Badanjilin Desert. The role and impact of the westerlies and the East Asian Summer Monsoon (EASM) systems on the climate change of the desert and even the whole plateau is a vexed question that brings different views in different periods. There is still a lack of definite evidence representing the events of global environmental change that occurred on the plateau during the discussed period. The distinctive morphology of dune mountains and the distribution of sand dunes are mutually indicative of the direction and energy of wind systems on the plateau. It is suggested that appropriate wind energy is the significant key to the desertification in these middle-latitude deserts on the plateau. From a global-scale review of climate change, the desertification of the modern-scale sandy desert landscapes on the Alashan Plateau is generally related to the global glacial period and the cold and dry climate during the past 40 ka.

Discussing the development and shrinkage process of glaciers is of great significance for the in–depth comprehension of regional environmental evolution and predicting global changes. However, there is little understanding of the developmental and retreat processes of mountain glaciers during the Late Quaternary (150 ka) in the East Asian Monsoon region. Using the latest chronological glacial data from eastern China, Taiwan, the Russian Far East, and the Japanese islands of Hokkaido and Honshu, which are all regions impacted by the East Asian Monsoon, we screened reliable glacial age data. This study compiled and compared the age sequences of the different mountain glaciations (dating techniques included optically–stimulated luminescence (OSL), thermoluminescence (TL), electron spin resonance (ESR), U–series (U), cosmogenic nuclides (10Be/CRN), carbon–14 (14C) and potassium–argon (K–Ar), etc.). Based on the evolutionary features of the glaciations in these mountains, by comparison with the marine isotope stage (MIS) environment, the influence of monsoonal circulation patterns on the regional development of glaciers was analyzed. This study determined that Japanese mountain glacial stages since 150 ka are the most complete in the East Asian Monsoon region, having developed during MIS 6–1. Taiwanese mountain glaciers developed during MIS 4–1, but glacial stages in continental East Asia were relatively short, with glaciers first developing only during MIS 3b–1. The reason for this this phenomenon is that the tectonic uplift in different subregions was significantly different; on the other hand, it is also related to the difference of precipitation between land and sea in monsoon climate. By comparing the glacial glaciations in the East Asian Monsoon region with western China, we found that there were significant differences between the extent, onset time, and length of glacial periods. Since the Last Glacial Period, precipitation levels have become transitional and concentrated during the summer months, and temperatures have been continuously changing as a result of the many periodic changes in the East Asian Monsoon. From the Early Last Glacial Period (MIS 4) to the Middle Last Glacial Period (MIS 3b) to the Last Glacial Period (MIS 2/LGM–YD), climatic conditions increasingly restricted the development of glaciers; the regional environment continued to warm until glaciers completely disappeared during the Late Holocene.

We consider the sea level, air–sea heat flux, and wind stresses and use an ocean model to investigate the evolution of the Kuroshio path and intensity during the last 35,000 years. Relative to the present, the Kuroshio during the last glacial period traveled the same path albeit with higher surface velocity in the East China Sea, while it migrated northward south of Japan and southward at the Kuroshio Extension (KE). The southward migrations of the KE axis were closely related to the positions of zero wind‐stress curl. To a certain extent, stronger glacial trade winds enhanced the North Equatorial Current. Consequently, Kuroshio transport increased in the southern and middle Okinawa Trough. Regarding Kuroshio strength, we suggest that the horizontal gradient of the subsurface temperature would be a better indicator than the upper‐ocean vertical thermal gradient, which is a commonly used index in paleoceanography. Plain Language Summary: The last glacial age was characterized by millennial‐scale climate variations and sea‐level changes. Although the path and intensity of the Kuroshio during the last glacial age have been studied extensively, the evolution of the Kuroshio is still poorly understood because of limited observations and incomplete model configurations. Using an improved ocean model and paleoclimate air–sea forcing field, we simulated the changes in the Kuroshio and Kuroshio Extension (KE) from 35,000 years ago to the present. Compared to the present, the North Pacific subtropical gyre including its southern and northern boundaries (i.e., North Equatorial Current and KE) shifted southward during the glacial age, which was associated with the changes in the wind‐stress curl over the North Pacific. The North Equatorial Current and its northern branch (i.e., Kuroshio) was enhanced during the last glacial period. Consequently, the Kuroshio transport increased with a higher surface velocity in the southern and middle East China Sea. With sea level lowering and climatic variations at glacial times, the Kuroshio path south of Japan shifted northward. The KE shifted southward with a range of 0.5–3.5°, which depended on the longitudes. The Kuroshio Current at 6 ka became similar to that of modern day. Key Points: Ocean modeling suggests that, due to an enhanced North Equatorial Current, Kuroshio was stronger during last glacial period than at presentSouthward migration of the Kuroshio Extension during the last glacial period was between 0.5 and 3.5° depending on the longitudesModel results indicate that the vertical thermal gradient in the upper ocean is not a suitable indicator of the Kuroshio intensity [ABSTRACT FROM AUTHOR]

The last glacial period was marked by interhemispheric coupling of abrupt climate changes in the northern and the southern high latitude regions through the "bipolar seesaw" mechanism. However, the spatial footprint of the bipolar seesaw in the mid‐latitude Indian sector of the Southern Ocean and its likely transmission into the tropical region is not well understood. Here, we have reconstructed the first multi‐centennial record of past SST variability in the Indian sector of the Southern Ocean spanning parts of MIS‐3, the last deglaciation, and the early to mid‐Holocene period using Mg/Ca of G. bulloides. We find that SST increased by around 4°C between the last glacial period and the early Holocene at the study site. Using this paleotemperature reconstruction and an independently available paleo‐simulation, we show that the mid‐latitude climate evolution in the Indian sector had signatures of both local‐scale changes and those emanating from the coupled bipolar influence. We further show that most of the millennial variance in Indian monsoon records during the period was linked to mid‐latitude SST variability in the Indian sector. Plain Language Summary: The impact of polar and high‐latitude climate variability on the tropical climate systems is an active area of research. While the variability of the Indian summer monsoon is relatively well understood on both very short (modern era) and very long (orbital) timescales, factors governing its sub‐orbital variability are not well constrained. Using simulated climate data and through our reconstruction of past quantitative climate data, we show that the temperatures of the mid‐latitudes of the Indian sector of the Southern Ocean governed the sub‐orbital variability of Indian summer monsoon, causing a series of abrupt changes in monsoon intensity on millennial‐scale during the last glacial period. Key Points: First high‐resolution quantitative climate (SST) reconstruction in the Indian sector of the Southern OceanThe multi‐centennial SST record reveals a cooling trend during the Holocene and an Antarctic‐type deglacial riseSouthern mid‐latitude SST acts as a control on the Indian Summer Monsoon during the last glacial period [ABSTRACT FROM AUTHOR]

The climate in central Europe during the last 60 ka is characterized by rapid temperature and moisture changes and strong cold periods (Heinrich events). All these variations are preserved in sediments of marine and also some terrestrial archives. Here we present a continuous, terrestrial sediment record with almost all Greenland stadials and Heinrich events between 60 and 13 ka visible from carbonate roundness of the Eifel Laminated Sediment Archive Dust Stack-20 and CaCO3 data for central Europe. The carbonate roundness data show almost all stadials between 60 and 13 ka. CaCO3 data show a general transport system change with the beginning of Heinrich event 3. Since there are no carbonates west of the Auel Maar, we conclude that the eolian-transported grains were not transported by westerly but easterly winds. These postulated easterly winds during the last glacial maximum are supported by similar findings of previous works. [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]

The upper branch of the Atlantic meridional overturning circulation (AMOC) plays a critical role in ocean circulation and climate change, yet its variability during the last glacial period is poorly documented. Here, we investigate the northward‐flowing Glacial Eastern Boundary Current (GEBC) in the North Atlantic, known today as the European Slope Current, and representing the easternmost portion of the upper branch of the AMOC. Based on flow speed and isotopic records, we show that Dansgaard‐Oeschger (D‐O) interstadials (stadials) correspond to a faster (weaker) GEBC during the ∼50–15 ka period. This, by analogy to present‐day conditions, suggests enhanced (reduced) strength of the subpolar gyre and, by extension, of northern‐sourced water production and AMOC during D‐O interstadials (stadials). Concomitant fluctuations of both the GEBC and the European Ice Sheet between ∼30 and 17 ka suggest an active role of the upper branch of AMOC in the poleward transport of heat and freshwater to the northern North Atlantic, with direct impacts on deep water formation and AMOC strength. We explore these ice‐sheet—AMOC interactions and the associated abrupt climate changes over the last glacial period and the last deglaciation. Key Points: The strength of the upper branch of Atlantic meridional overturning circulation (AMOC) is reflected in variations of the Glacial Eastern Boundary Current along the European marginSedimentological data show a Dansgaard‐Oeschger interstadial/faster‐stadial/slower flow patternFaster upper AMOC in the east basin corresponds with increased deep return flow in the west [ABSTRACT FROM AUTHOR]

In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ18O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ18O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ18O profile of this stalagmite may imply millennial-scale changes, and high δ18O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ18O values; the mean δ18O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ18O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ18O for the last glacial period in Fukugaguchi Cave most likely resulted from 18O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ18O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of 18O depletion in Japan Sea surface water during the last glacial period. [ABSTRACT FROM AUTHOR]

The source of Maebashi volcanic mudflow deposits, major basement strata of Maebashi-Takasaki area in central Japan, has been elucidated to be Kurofu volcano, an initial stage volcanic edifice of Asama volcano located about 50km west of these cities. This conclusion is based on the Sr isotope analysis of large volcanic blocks within the mudflow deposits. 14C dates of buried wood blocks also indicate that major failure event occurred ca.27 ka cal BP, and older ages of more than 10 ka suggest that another failure may also have occurred before ca.27 ka cal BP, although its scale is unknown. In order to get some clues for the activity of the ancestral Asama volcano, we collected two wood blocks during the field survey in Naganohara Town in the upper reaches of the Agatsuma River to the north of Asama volcano. One sample collected from the outcrop on the left bank of the Agatsuma River at Kawarabata yielded 22.35 ± 0.09 ka BP. This result is identical with the 14C age data for major wood blocks from the Maebashi mudflow deposits, suggesting a deposition during the same event at ca.27 ka cal BP. However, another sample from the outcrop at the northern margin of Ookuwa area in the northern foot of Asama volcano, yielded no detected 14C, indicating an older age of more than ca.45 ka cal BP. This sample occurs in a chaotic deposit containing silt blocks of lake sediment cemented by volcanic materials. Thus, the volcanic deposits of these two sites appear to be different in origin and age. Detailed study on volcanic deposits in time and space in this source area of the Maebashi mudflow deposits is required for more understanding of failure events of the initial stage of Asama volcano. [ABSTRACT FROM AUTHOR]

The last glacial period (LGP) promoted a loss of genetic diversity in Paleolithic populations of modern humans from diverse regions of the world by range contractions and habitat fragmentation. However, this period also provided some currently submersed lands, such as the Sunda shelf in Southeast Asia (SEA), that could have favored the expansion of our species. Concerning the latter, still little is known about the influence of the lowering sea level on the genetic diversity of current SEA populations. Here, we applied approximate Bayesian computation, based on extensive spatially explicit computer simulations, to evaluate the fitting of mtDNA data from diverse SEA populations with alternative evolutionary scenarios that consider and ignore the LGP and migration through long-distance dispersal (LDD). We found that both the LGP and migration through LDD should be taken into consideration to explain the currently observed genetic diversity in these populations and supported a rapid expansion of first populations throughout SEA. We also found that temporarily available lands caused by the low sea level of the LGP provided additional resources and migration corridors that favored genetic diversity. We conclude that migration through LDD and temporarily available lands during the LGP should be considered to properly understand and model the first expansions of modern humans.

Reconstruction of the desert paleoclimate is important to understand the mechanisms that triggered and/or enhanced climate change. Through optically stimulated luminescence (OSL) dating, grain size, magnetic susceptibility, X-ray powder diffraction (XRD) and geochemical indicators, we provide a well-dated record of a sedimentary outcrop on the southeast margin of the Bardain Jaran Desert, Northwest China, during the last glacial period. Four Qz-OSL ages are obtained, 41.0±34 ka, 54.7±4.4 ka, 59.5±5.0 ka and 66.8±5.8 ka, corresponding to the depths of 35 cm, 70 cm, 150 cm and 200 cm respectively. Indicators like grain size, clay content, magnetic susceptibility, XRD and geochemical index (e.g. Sr, Ba, Sr/Ca) jointly indicate abrupt climate changes at the depth of 35 cm (age, ca. 41.0 ka) and 200 cm (age, ca. 67 ka). Namely, the 280 cm sedimentary outcrop perfectly records a warm wet climate stage, corresponding to the late Marine Isotope Stages (MIS) 4 to the early MIS 3. Besides, there is a trend of grain size increase after around 40 ka BP, which is most likely a signal of wind strength change. Our research supports that enhancing Siberian High pressure system during the late MIS 3 played a key role in NW East Asia climate evolution. [ABSTRACT FROM AUTHOR]

Obtaining accurate temperature reconstructions from the past is crucial in understanding the consequences of changes in external climate forcings, such as orbital-scale insolation or multidecadal to centennial-scale variability on the climate system and the environment. In addition, these reconstructions help in comprehending the amplitude of natural temperature changes in the past, which can assist in evaluating the amplitude and rate of recent anthropogenic global warming. Here we present the first detailed Holocene mean July air temperature reconstruction based on chironomid assemblages from sediments retrieved from Laguna de Río Seco, an alpine lake in Sierra Nevada, southern Spain. Coldest climate conditions are recorded during the last glacial maximum and the last deglaciation. Warming occurred in the Early Holocene and warmest summer temperature conditions and the Holocene thermal maximum (HTM) occurred in the interval roughly between 9000 and 7200 cal yr BP, concurrent with summer insolation maxima. Rapid cooling of ∼1.5 °C occurred after the warmest maximum and between ∼7200 and 6500 cal yr BP, and temperatures stabilized between ∼6500 and 3000 cal yr BP. A further cooling began ∼3000 cal yr BP and culminated with coldest summer conditions during the Dark Ages (DA) and Little Ice Age (LIA) at ∼1550 cal yr BP (∼400 CE) and ∼200 cal yr BP (∼1750 CE), respectively. This cooling temperature trend was interrupted by warmer conditions during the Iberian-Roman Humid Period (IRHP) ∼2000 cal yr BP and during the Medieval Climate Anomaly (MCA) at ∼1000 cal yr BP. Our reconstruction shows a greater than two-degree cooling during the Middle and Late Holocene, agreeing with global mean surface temperature (GMST) reconstructions. Modern climate warming (MCW) during summer exceeds the two-degree Celsius forecasted for the future due to anthropogenic greenhouse gases, suggesting that recent warming is amplified at high elevations. Alpine environments and the biodiversity contained there are thus in danger if the observed temperature trend continues in the next decades. • Coldest summer air temperatures occurred in the last glacial and the last deglaciation. • Warming happened during deglaciation and Early Holocene related to insolation. • Thermal maximum occurred in the interval between ∼9000 and 7200 cal yr BP. • Cooling occurred in the Middle and Late Holocene, • Modern climate warming during summer in Sierra Nevada exceeds 2 °C. [ABSTRACT FROM AUTHOR]

The sedimentary sequences superimposed by loess and paleosol are widely d:stributed in the northern of Shandong peninsula. Based on the field investigation and photoh iminescence dating, the grain size and the characteristics of fractal dimension of loess sediments from Zhifu island in Yantai area of Shandong were calculated by graphical method and power exponential function method . and Late Pleistocene climate environment and evolution in the northern of Shandong peninsula were studied. The results show that the formation age of Zhifu section is 62. 85- 124.90 ka B. P., corresponding to last glacial last inierglacial periods, and is composed of sandy loess, loess and paleosol; the sediment from Zhifu section has a good fractal structure . which can clearly distinguish the paleosol (the fractal dime sio is 2. 379) . loess (2. 191). a d sa dy loess loess (2. 157); the fractal dime sio has a sig ifica t positive correlation with the standard deviation. the correlation coefficient isO. 889 1; ii has a high po shive correlation with the average grain size and a lcjw correlation with the kurtosis and skewness; the fractal dimension of sediment from Zhif u section show remarkable variations in alternation of peaks and valleys vertically. which can be used as an indicator of sedimentary environment; the low fractal dimension reflects the dry and cold climate, and the winter wind is strong and loess accumulation accelerates, on the contrary. the climate is warm and humid, and the paleosol is developed. [ABSTRACT FROM AUTHOR]

The Earth has experienced large changes in global and regional climates over the past one million years. Understanding processes and feedbacks that control those past environmental changes is of great interest for better understanding the nature, direction and magnitude of current climate change, its effect on life, and on the physical, biological and chemical processes and ecosystem services important for human well-being. Microfossils from terrestrial plants – pollen, microcharcoal and phytoliths – preserved in terrestrial and marine sedimentary archives are particularly useful tools to document changes in vegetation, fire and land climate. They are well-preserved in a variety of depositional environments and provide quantitative reconstructions of past land cover and climate. Those microfossil data are widely available from public archives, and their spatial coverage includes almost all regions on Earth, including both high and low latitudes and altitudes. Here, we (i) review the laboratory procedures used to extract those microfossils from sediment for microscopic observations and the qualitative and quantitative information they provide, (ii) highlight the importance of regional and global databases for large-scale syntheses of environmental changes, and (iii) review the application of terrestrial plant microfossil records in palaeoclimatology and palaeoecology using key examples from specific regions and past periods. [ABSTRACT FROM AUTHOR]

The thick ' Xiashu loess' in southern China is distributed not only in the Yangtze River valley, but also and most extensively in the region between the Qinling Mountains and the lower reaches of the Yangtze River. However, there are few studies of the provenance and climatic implications of the Xiashu loess in this latter region. Here we present the results of a provenance study of Last Glacial loess samples from twenty-two typical Xiashu loess sections, using the major and trace element composition as a provenance indicator. Seventeen of the sites are located to the north of the Yangtze River and our primary aim was to determine the provenance of the Xiashu loess within this region. Our results indicate that the alluvial plain located mainly in the present drainage area of the Huai River was the primary dust source for the Xiashu loess in this region. The occurrence of multiple local dust sources within this alluvial plain, suggested by their geochemical heterogeneity, indicates that the alluvial plain experienced intensified aridity which caused it to become a dust source for local loess deposits in northern subtropical China during the Last Glacial. Our study provides strong evidence to challenge the long-held view that the occurrence of Xiashu loess resulted from the southward incursion of the CLP loess deposits sourced from deserts of the Asian interior, and it confirms the substantial role of aridification of the present humid northern subtropical region for dust emission to the climate system during the Last Glacial. • Major and trace element composition of samples from 22 Xiashu loess sections. • The Xiashu loess was not primarily derived from the Asian interior deserts. • Geochemical heterogeneity indicates local dust sources in the alluvial plain. • Alluvial plain in northern subtropical China aridified during the Last Glacial. [ABSTRACT FROM AUTHOR]

Mineralogical compositions and grain-size distributions combined with 87Sr/86Sr and ε Nd values of the detrital fraction were studied on cores recovered from the Gulf of Aden (MD92-1002) and the Red Sea (MD92-1008) basins in order to document past changes in Indian monsoon and northwesterly winds during the last glacial-interglacial transition (the last 20 ka), encompassing the African Humid Period (AHP). The ε Nd vs. 87Sr/86Sr plot indicates that sediments result from the mixing of two main sedimentary sources corresponding to the Afar volcanic rocks in Ethiopia and to the Arabian-Nubian Shield. Variations of sediment isotopic and mineralogical composition point to a diminution of the volcanic source contribution during the last deglaciation. Changes of mineral-accumulation rates and grain-size distributions denote a decline in the aridity of the source regions during the Holocene, particularly of the Afar volcanic region. In this area, the reduction of detrital supply, from 15 cal ka BP, can be explained by an increase of precipitations during the AHP, which resulted in an expansion of the vegetation cover and lake extensions in East Africa. In the Arabian Peninsula, precipitations were confined to the south, allowing sediments to be transported even during the Holocene. Our data suggest that the southwest monsoon was not the main carrier of aeolian sediments to the Red Sea and Gulf of Aden basins, but the Northwesterlies. In the Red Sea, the isotopic and mineralogical tracers reveal a contribution from Saharan dust between 16 and 12 cal ka BP, transported from the Nile catchment after aridification during Heinrich event 1. [ABSTRACT FROM AUTHOR]

Abstract Aeolian dune field chronologies provide important information on drought history on the Great Plains. The White River Badlands (WRB) dunes are located approximately 60 km north of the Nebraska Sand Hills (NSH), in the western section of the northern Great Plains. Clifftop dunes, sand sheets, and stabilized northwest-southeast trending parabolic dunes are found on upland mesas and buttes, locally called tables. The result of this study is a dune stabilization history determined from samples collected from stratigraphic exposures and dune crests. Thirty-seven OSL ages, from this and previous investigations, show three periods of dune activity: 1) ∼21,000 years ago to 12,000 years ago (a), 2) ∼9 to 6 ka, and 3) post-700 a. Stratigraphic exposures and low-relief dune forms preserve evidence of late Pleistocene and middle Holocene dune development, while high-relief dune crests preserve evidence of late Holocene dune development. Results of 12 OSL ages from the most recent dune activation event indicate that Medieval Climate Anomaly (MCA) droughts and Little Ice Age (LIA) droughts caused dune reactivation on the tables. Dune reactivation was accompanied by other drought-driven geomorphological responses in the WRB, including fluvial incision of the prairie and formation of sod tables. Regional significance of the MCA and LIA droughts is supported by similarities in the aeolian chronologies of the NSH at 700–600 a and some western Great Plains dune fields at 420–210 a. Aerial photographs of the WRB show little activity during the Dust Bowl droughts of the 1930s. [ABSTRACT FROM AUTHOR]

Enhanced ocean carbon storage during the Pleistocene ice ages lowered atmospheric CO2 concentrations by 80 to 100 ppm relative to interglacial levels. Leading hypotheses to explain this phenomenon invoke a greater efficiency of the ocean's biological pump, in which case carbon storage in the deep sea would have been accompanied by a corresponding reduction in dissolved oxygen. We exploit the sensitivity of organic matter preservation in marine sediments to bottom water oxygen concentration to constrain the level of dissolved oxygen in the deep central equatorial Pacific Ocean during the last glacial period (18,000–28,000 years BP) to have been within the range of 20–50 μmol/kg, much less than the modern value of ~168 μmol/kg. We further demonstrate that reduced oxygen levels characterized the water column below a depth of ~1,000 m. Converting the ice age oxygen level to an equivalent concentration of respiratory CO2, and extrapolating globally, we estimate that deep‐sea CO2 storage during the last ice age exceeded modern values by as much as 850 Pg C, sufficient to balance the loss of carbon from the atmosphere (~200 Pg C) and from the terrestrial biosphere (~300–600 Pg C). In addition, recognizing the enhanced preservation of organic matter in ice age sediments of the deep Pacific Ocean helps reconcile previously unexplained inconsistencies among different geochemical and micropaleontological proxy records used to assess past changes in biological productivity of the ocean. Plain Language Summary: Carbon dioxide (CO2) in Earth's atmosphere was lower during cold glacial periods of the last 800,000 years than during warm interglacial periods, by an amount equivalent to about one third of the preindustrial CO2 content of the atmosphere. It is thought that the ocean absorbed the CO2 missing from the atmosphere, but determining where and how the CO2 was stored in the ocean has remained a challenge. Photosynthesis in the surface ocean converts CO2 to organic matter, a portion of which sinks into the deep sea, where it is subsequently converted back to CO2 by respiration of the organisms that consume the organic matter. Stimulation of the biological uptake of CO2 in surface water, inhibition of the physical processes that raise deep waters back to the surface where they exchange gases with the atmosphere, or any combination of the two would enhance the storage of CO2 in the deep ocean while also reducing the concentration there of dissolved oxygen. Here we show that the oxygen concentration in deep waters of the Pacific Ocean was much lower during the last glacial period than today. The difference is sufficient to accommodate the CO2 removed from the atmosphere during the ice ages. Key Points: Deep Pacific dissolved oxygen was much lower than today during the last glacial period (focusing on the interval 18,000–28,000 years BP)Ice age ocean storage of carbon was sufficient to explain low atmospheric CO2 levelsEnhanced preservation in sediments of organic compounds under low dissolved oxygen reconciles paleoproductivity proxies [ABSTRACT FROM AUTHOR]