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Palaeo–hydrological and sedimentary investigations were carried out in the Longmenxia Gorge of the middle Yihe River. Five bedsets of flood slackwater deposits (SWD) were found interbedded into Holocene aeolian loess–soil profiles in the river bank at the Longmenxia site. They were identified as the deposits of the suspended sediment load during the extreme flood events of the Holocene. The minimum flood peak discharges were estimated to be 12, 300–15, 300 m 3 /s using the slope–area method. These are about twice the largest gauged record (7180 m 3 /s) that has occurred since 1937. These flood events occurred at 3100–3000 a B.P., 1800–1700 a B.P., 700–550 a B.P. and 350–250 a B.P., as dated by optically stimulated luminescence (OSL) in combination with stratigraphic correlation, to which may be added the recorded events of the 223 and 1761 CE floods. These were associated with Holocene monsoonal shifts and abrupt climatic events. This research not only provides palaeoflood discharge estimates on the middle Yihe River, but also provides important data for understanding interactions between regional hydro–climatic systems and global climate change in humid and semi–humid monsoonal regions, such as China. [ABSTRACT FROM AUTHOR]

Climate change, sea level fluctuations, and tectonic uplift play key roles in the evolution of sedimentary systems on continental margins. In the Arabian Sea, the Makran continental margin is suitable for studying these processes during the Holocene due to its high sedimentation rate and continuous sequence of Holocene sediments. Here, high‐resolution clay mineral and grain size analyses have been conducted to better understand the sedimentary process and controlling factors over the past 13,000 yr. The results show that the influence of Indus‐derived sediments on the Makran continent margin is negligible. Holocene relative sea level fluctuations can strongly control the shelf accommodation space due to the narrow shelf, which in turn affects the deposition process at the Makran continental margin. The sediment records at the central Makran continental margin are more suitable for studying ancient earthquakes or tsunamis. Plain Language Summary: Deciphering sediment records is challenging because linking the sedimentary process with related major influencing factors is not always straightforward. Although previous studies have shown that climate is an important influencing factor in the sedimentary history of the Makran continental margin, the roles of other influencing factors remain poorly understood. The findings of this study provide new insights into the sedimentary process on the Makran continental margin over the past 13,000 yr based on high‐resolution clay mineral and grain size analyses. Our clay mineralogy data provide further evidence that the Indus River is unimportant to the sedimentary process on the Makran continental margin. Combined with the results of previous studies, this work demonstrates that the relative sea level fluctuations since the Holocene have played an important role in the sedimentary process at the Makran continental margin. In the central continental margin, river sediments, wave‐erode sediments, and eolian dust are all important source materials, suitable for studying event deposition related to earthquakes and tsunami due to the limited role of rivers. Key Points: Climate change is not the only decisive factor controlling the sedimentary processIndus‐derived sediments are unimportant on the Makran continental marginRelatively low sea levels seem to have played a major role in the early Holocene [ABSTRACT FROM AUTHOR]

This paper presents a reconstruction of the history of development of the ecosystems in the lower reaches of the Knevichanka River over the past 5350 cal BP based on the biostratigraphic analysis of the sediments of the first terrace above the floodplain. Differences were identified and characteristics were determined in the vegetation structure during the final phase of the Holocene climate optimum and multidirectional climatic fluctuations in the Late Holocene. It has been found that in the final phase of the Holocene broad-leaved plants were more widespread on the mountain slopes than at present. The alluvial plains predominantly contained grassy meadows with small-leaved plant communities. Mixed forests prevailed in the vegetation on the slopes of the Knevichanka River valley with a dominance of Korean pine, Japanese red pine, oak, elm, Amur cork tree, linden, lilac, Manchurian walnut, and other species. In the lower reaches of the Knevichanka River, in the place of the marshy plains and water areas of Lakes Krolevetskoe and Orlovskoe, an extensive shallow sea bay existed, which was connected to the Ussuri Bay via a narrow strait. A cooling period that began at the end of the Middle Holocene and continued into the beginning of the Late Holocene led to a reduction of broad-leaved plants in vegetation and more widespread occurrence of small-leaved plants. At that time, the formation of the soil layer of the first terrace above floodplain began in the lower reaches of the river. In the course of the marine regression, the coastal lowlands became free from seawater, and the upper part of the shallow bay was detached from the sea. A lagoon occurred at the location of the marine gulf. The lagoon became gradually freshened, shallow, and connected to the sea by the channels of the Knevichanka and Artemovka rivers. However, during the syzygial tides and wind-induced surges, seawater still intruded regularly. At the end of the Late Holocene, the valley of the Knevichanka River developed natural conditions, thus giving rise to the recent structure of vegetation. Desalination occurred in lakes Krolevetskoe and Orlovskoe, while they acquired their recent outlines. [ABSTRACT FROM AUTHOR]

The Hunshandake Sandy Land in the northern part of China is the northern sand barrier of China's key ecological functional zone. The climate change in the Holocene in this area provides a scientific basis for controlling the sandstorm sources affecting Beijing and Tianjin. Currently, there is no consensus on the changes in humidity that occurred during the early Holocene. Based on optically stimulated luminescence (OSL) and AMS 14C dating of two aeolian sections, combined with magnetic susceptibility, grain size, colour parameters and geochemical element climatic proxies, we reconstructed Holocene climatic changes in the Hunshandake Sandy Land. Optimum climatic conditions occurred during 8.4–4.2 ka, when the monsoon precipitation was the strongest. After ∼4.2 ka, the climate was dominantly semi-humid to arid. By reviewing the aeolian and lake records from the other Hunshandake Sandy Land records, we suggest that the early Holocene was characterized by shallow lakes or rivers in low-lying areas, suggesting increased snowmelt driven by high solar radiation and increased surface runoff where surface vegetation is sparse. We observed a sudden shift in the layers from river/lake sands to palaeosols, along with abrupt changes in multiple indicators, corresponding to sedimentation linked to the 8.2 ka and 4.2 ka events. By comparing the East Asian summer monsoon precipitation, Northern Hemisphere summer insolation, and ice volume area, we suggest that the evolution of the Holocene East Asian monsoon was influenced by a combination of changes in the Northern Hemisphere ice sheet and solar radiation, which drove climate change in the Hunshandake Sandy Land. • Two aeolian sections in Hunshandake reveal an optimum climate during 8.4–4.2 ka. • The early Holocene was characterized by shallow lakes or rivers in low-lying areas. • The observable lithologies and indicators changed abruptly at the 8.2 ka and 4.2 ka climate events. [ABSTRACT FROM AUTHOR]

Rivers are the main water source for the oases, and rivers are essential for the wellbeing of the human inhabitants in the desert areas. The Keriya River flows through the south–central Taklimakan desert, the second largest mobile desert on Earth, in northwest China. The earliest archaeological site in the interior of the Taklimakan Desert together with the remains of several ancient cities are located along the Keriya River. Accurately dating the dry watercourses and ancient sites in this region is critical for understanding the changes in fluvial hydrology and their relationship with human activities in desert areas. Specially, the interactions between the hydrological processes of the Keriya River, and human activities are poorly understood due to the lack of a reliable chronology for this river associated with these ancient sites. In this study, we collected 18 samples from 12 fluvial and lacustrine sedimentary sequences for optically stimulated luminescence (OSL) dating, and we also, reviewed 23 dating results from previous studies to reconstruct the hydrological processes of the Keriya River since the early Holocene. Additionally, we also tested 28 14C dates from three ancient sites, combined with 33 14C dates from previous studies to reconstruct a timeline of human migration within the desert. The results show that the Keriya River retreated continuously from the early Holocene onward, due to the decreased supply of glacial meltwater and precipitation in the surrounding mountains, and this process triggered human migrations from north to south in the Taklimakan Desert after ∼3.5 ka. Overall, our findings reveal that variations in fluvial hydrological processes can trigger human migration in desert areas under the background of the global climate change. • We established the hydrological processes and human migration history along the Keriya River since the early Holocene. • The retreat of the river was synchronized with the human migration to the southern Taklimakan Desert. • The decreased supply of glacial meltwater and precipitation in the Kunlun Mountains triggered the river retreat. • The hydrological status and human settlements in the desert/arid area were sensitive to climate changes. [ABSTRACT FROM AUTHOR]

Aim. We use ecological niche models and environmental stratification of palaeoclimate to reconstruct the changing range of the lion (Panthera leo) during the late Pleistocene and Holocene. Location. The modern (early 21st century) range of the lion extends from southern Africa to the western Indian Subcontinent, yet through the 20th century this range has been drastically reduced in extent and become increasingly fragmented as a result of human impacts. Methods. We use Global Environmental Stratification with MaxEnt ecological niche models to map environmental suitability of the lion under current and palaeoclimatic scenarios. By examining modelled lion range in terms of categorical environmental strata, we characterise suitable bioclimatic conditions for the lion in a descriptive manner. Results. Wefind that lion habitat suitability has reduced throughout the Holocene, controlled by pluvial/interpluvial cycles. The aridification of the Sahara 6ka dramatically reduced lion range throughout North Africa. The association of Saharan aridification with the development of pastoralism and the growth of sedentary communities, who practised animal husbandry, would have placed additional and lasting anthropogenic pressures on the lion. Main Conclusions. This research highlights the need to integrate the full effects of the fluctuating vegetation and desiccation of the Sahara into palaeoclimatic models, and provides a starting point for further continental-scale analyses of shifting faunal ranges through North Africa and the Near East during the Holocene. This scale of ecological niche modelling does not explain the current pattern of genetic variation in the lion, and we conclude that narrow but substantial physical barriers, such as rivers, have likely played a major role in population vicariance throughout the Late Pleistocene. [ABSTRACT FROM AUTHOR]

We determined the sequence of formation of deposits on the first terrace above the Tarbagataika river floodplain, and a change of the sedimentation and soil-formation stages for the last 7 kyr. We reconstructed the accumulation dynamics of the sediment layer and calculated the mean sediment accumulation rates for different time intervals. The phases of intensification of erosion-accumulation and aeolian processes were recorded. The study revealed the main stratigraphic boundaries reflecting the fundamental changes of the settings of sedimentation: 7 cal. kyr BP, a change of riverbed sedimentation for floodplain sedimentation; 5.4 cal. kyr BP, intensification of erosion-accumulation processes due to climate aridization on the Atlantic-Subboreal boundary, and active input of erosion products to the floodplain; 4 cal. kyr BP, active filling of the river valley with horizontally layered polygenetic fine-grained sands and sandy loams containing intercalations of humic warps in conditions of the overlapped (built-up) floodplain with an increase in humidification in the middle of the Subboreal period and, as a consequence, an increase in the height of floods; 3.4 cal. kyr, the layer under investigation leaves the floodplain regime of sedimentation and accumulation of aeolian-deluvial deposits, and 1 cal. kyr, intensification of erosion-accumulation processes due to climatic and anthropogenic changes. We reconstructed the chronology and specific features of the pedogenesis stages which record the phases of temporal cessation of floodplain and slope sedimentation on the study territory. The results obtained are in good agreement with data on the hydraulicity of rivers, the stages of soil formation and on the manifestation of exogenous processes on the territories of Russia and Mongolia. [ABSTRACT FROM AUTHOR]

In the eastern United States, existing paleo-reconstructions in fluvial environments consist primarily of site-specific investigations of climate and human impacts on riverine processes. This paper presents the first meta-analysis of fluvial reconstructions focused on regional watersheds of the eastern United States, including the Lower Mississippi, Tennessee, South Atlantic–Gulf Coast, Ohio, Mid-Atlantic, and New England regional watersheds. Chronologies of fluvial activity (i.e. alluvial deposition) and stability (i.e. landscape stability) were developed by synthesizing data from existing, published, and site-specific fluvial reconstruction studies conducted across the eastern United States. Overall, regional watersheds show variable patterns of synchronicity across watersheds and did not demonstrate cyclic behavior through the Holocene. During the last millennium, only the Lower Mississippi and Ohio regional watersheds exhibit high rates of fluvial activity active during the 'Medieval Climate Anomaly' (650–1050 yr BP), while nearly all other regional watersheds in the eastern United States were active during the 'Little Ice Age' (100–500 yr BP). These findings imply that fluvial activity may be more spatially restricted during warmer/drier climatic conditions than during cooler/wetter periods. We find an increase in fluvial activity during the era of Euro-American colonization (400 yr BP to present) in the southeastern United States but not the northeastern United States, implying a heterogeneous response of fluvial systems to human activities in the eastern United States related to climatic, cultural, and/or physiographic variability. These new insights gained from fluvial chronologies in the eastern United States demonstrate the utility of regionally synthesized paleo-records to understand large-scale climate variation effect on rivers. [ABSTRACT FROM AUTHOR]

Seven main periods of soil formation can be distinguished in the floodplain of the Moskva (Moscow) River, with the oldest paleosols dated to the Allerød age. We analyzed paleosols buried under alluvial deposits, colluvial sediments, and archaeological deposits within the catchment area of the Moskva River. Paleopedological reconstructions were correlated with the results of the pedoanthracological and palynological analyses. Series of radiocarbon (14C) dates were obtained on humic acids and dispersed macro-charcoal from paleosols and archaeological features. Wide time frames of the floodplain paleosol formation were determined at a 95% probability as 14,600–12,600 cal BP for Soil 7; 9500–7000 cal BP for Soils 6 and 5; 6700–5500 cal BP for Soil 4; 5000–4400 cal BP for Soil 3b; 4100–2700 cal BP for Soil 3a; and 2000–700 cal BP for Soil 2. The dates were compared with the age of archaeological sites from the same areas. The comparison revealed a close correspondence between the ages of the soil charcoal and the timing of archaeological occupations. That allowed us to conclude that the fire occurrence on a regional level was associated mainly with the human occupation. The fire record is especially pronounced in floodplain paleosols, due to both the role of rivers as human migration corridors, and the integral accumulation of combustion products from the entire catchment area in these paleosols. [ABSTRACT FROM AUTHOR]

Palaeochannels of lowland rivers provide a means of investigating the sensitivity of river response to climate-driven hydrologic change. About 80 palaeochannels of the lower Macquarie River of southeastern Australia record the evolution of this distributive fluvial system. Six Macquarie palaeochannels were dated by single-grain optically stimulated luminescence. The largest of the palaeochannels (Quombothoo, median age 54 ka) was on average 284 m wide, 12 times wider than the modern river (24 m) and with 21 times greater meander wavelength. Palaeo-discharge then declined, resulting in a younger, narrower, group of palaeochannels, Bibbijibbery (125 m wide, 34 ka), Billybingbone (92 m, 20 ka), Milmiland (112 m, 22 ka), and Mundadoo (86 m, 5.6 ka). Yet these channels were still much larger than the modern river and were continuous downstream to the confluence with the Barwon-Darling River. At 5.5 ka, a further decrease in river discharge led to the formation of the narrow modern river, the ecologically important Macquarie Marshes, and Marra Creek palaeochannel (31 m, 2.1 ka) and diminished sediment delivery to the Barwon-Darling River as palaeo-discharge fell further. The hydrologic changes suggest precipitation was a driving forcing on catchment discharge in addition to a temperature-driven runoff response. [ABSTRACT FROM AUTHOR]

Mountain regions such as the Lesser Caucasus are a focus of ongoing environmental changes. To understand their future evolution, information about their former geomorphic and environmental dynamics is required. The former fluvial dynamics derived from fluvial sediment archives can offer such insights. However, the fluvial dynamics of the Lesser Caucasus since the Eemian interglacial have not been systematically investigated so far. Thus, we have studied late Pleistocene and Holocene sediments of several rivers originating from the central Lesser Caucasus. The studied rivers show a mostly coherent record of fluvial dynamics: Minor aggradation occurred during early Marine Isotope Stage (MIS) 5, incision during late MIS 5 or early MIS 4, intensive silty aggradation at least during late MIS 3, incision during early MIS 2, coarse-grained aggradation probably during some millenia until ca. 19 ka, and aggradation ca. 14-13 ka. Following incision around the Pleistocene/Holocene transition, aggradation resumed around 6.0, 3.4 – 2.0 and 0.5 – 0.15 cal. ka BP. Generally, periods of aggradation, incision and stability could be linked with regional climatic or anthropogenic influences on regional landscape stability and water availability. The fluvial dynamics of the central Lesser Caucasus mostly differed even between neighbouring regions, and only in cases of significant hemispheric climatic fluctuations as around 20 ka, during the Pleistocene/Holocene transition or the Little Ice Age, were similar over-regional fluvial patterns observed. This demonstrates the individual character of river systems especially in mountain regions such as the southern Caucasus with strong geoecological gradients. Thus, to understand the former landscape dynamics of mountain landscapes, investigations of fluvial sediment archives on a regional to sub-regional scale are necessary. [ABSTRACT FROM AUTHOR]

During the Holocene, the upper and middle reaches of the Yellow River valley in China were pivotal areas for agricultural development. Quantitatively reconstructing the spatiotemporal changes in prehistoric human land use is essential for understanding, from a long-term perspective, the interactions among evolutions of climate, agriculture, and human activities. Based on 327 archaeological sites and the PLUM (prehistoric land use model), we quantitatively reconstructed human land use changes from 6 to 3 ka BP (thousands of years before the present) in the Tao River valley, the second-largest tributary in the upper reach of the Yellow River valley. The results indicated that regional land use areas increased from 571 km2 to 1468 km2, with spatial expansion from the lower reach to the upper–middle reach of the Tao River valley. A comparison of the five areas distributed across the upper and middle reaches of the Yellow River valley revealed two different trends of increasing land use from 8 to 3 ka BP within these areas. The first group (the Wei River and Yiluo River valleys) exhibited rapid and substantial growth before 5 ka BP, while the second group (the Huangshui River and Tao River valleys, and the Yunlin district) showed a much slower and less significant increase before 5 ka BP, but a more obvious increase thereafter. The asynchronous increases in these areas indicate an expansion of land use from the southeastern part of the upper and middle reaches of the Yellow River Valley to across the entire region between 8 and 3 ka BP, which was primarily driven by agricultural development and cultural communication. [ABSTRACT FROM AUTHOR]

Central Asia (CA) is one of the world's most significant arid regions, which is markedly impacted by global warming. A better understanding of the dynamical processes governing its Holocene climate variability is critical for a better understanding of possible future impacts of climate change in the region. To date, most of the existing CA paleoclimate records are from the summer precipitation-dominated eastern CA (ECA), with few records from the winter precipitation-dominated western CA (WCA). Here, we present a precisely dated (~6‰) and highly resolved (<4-y) record of hydroclimatic variations from the WCA covering the period between 7,774 and 656 y BP. Utilizing multiple proxies (δ18O, δ13C, and Sr/Ca) derived from a stalagmite from the Fergana Valley, Kyrgyzstan, we reveal a long-term drying trend in WCA, which is in contrast with the wetting trend in ECA. We propose that different responses of winter and summer westerly jets to seasonal solar insolation over the past 8,000 y may have resulted in an antiphased precipitation relationship between the WCA and ECA. Our data contain dominant quasiperiodicities of 1,400, 50 to 70, and 20 to 30 y, indicating close connections between the WCA climate and the North Atlantic. We further identified a series of droughts and pluvials on centennial-to-decadal timescales, which may have influenced regional societies and trans-Eurasian culture exchanges during historical and prehistorical times. [ABSTRACT FROM AUTHOR]

The Indian summer monsoon (ISM), one of the dramatic illustrations of seasonal hydrological variability in the climate system, affects billions of lives. The ISM dominantly controls the northern Indian Ocean sea-surface salinity, mostly in the Bay of Bengal and the Andaman Sea, by the Ganga-Brahmaputra-Meghna and Irrawaddy-Salween rivers outflow and direct rainfall. In the past decade, numerous studies have used radiogenic neodymium (εNd) isotopes of seawater to link Indian subcontinent erosion and the ensuing increase in discharge that results in changes in the north Indian Ocean sea surface. Here we synthesized the state of the ISM and ocean circulation using the neodymium and hafnium isotopes from north Indian Ocean deep-sea sediments. Our data suggest that the Bay of Bengal and north Indian Ocean sea-surface conditions were most likely modulated by changes in the ISM strength during the last glacial-interglacial cycle. These findings contrast to the hypothesis that suggests that the bottom water neodymium isotopes of the northern Indian Ocean were modulated by switching between two distant sources, namely North Atlantic Deep Water and Antarctic bottom water. Furthermore, the consistency between the neodymium and hafnium isotopes during the last glacial maximum and Holocene suggests a weak and dry ISM and strong and wet conditions, respectively. These data also indicate that the primary source of these isotopes was the Himalayas. Our results support the previously published paleo-proxy records, indicating weak and strong monsoons for the same periods. Moreover, our data further support the hypothesis that the northern Indian Ocean neodymium isotopes were decoupled from the global ocean neodymium budget due to the greater regional influence by the great Ganga-Brahmaputra-Meghna and Irrawaddy-Salween discharge draining the Indian subcontinent to the Bay of Bengal and the Andaman Sea. [ABSTRACT FROM AUTHOR]

The main objective of the study was to reconstruct palaeoenvironmental changes recorded in lake and peatland sediments from the peatland located in the western part of Lublin Polesie, where no former palaeoecological research had been conducted, and to compare findings to changes reconstructed for other sites in the eastern part of this region. Climate changes were considered, as well as the effects of human impact, which intensified particularly after the Middle Ages. In recent times the trajectory of change of the Mytycze ecosystem was exceptional because in the 1960s this area was included in the Wieprz-Krzna Canal System, and then renaturated after the discontinued use of hydraulic engineering structures. This is the largest canal in Poland and runs in the immediate vicinity of the watershed supplied by two large rivers: the Bug and the Wieprz. The presented study mainly relied on the following proxies: pollen, testate amoebae and other non-pollen palynomorphs, and peat decomposition. Data from the Archaeological Picture of Poland (AZP) allowed for a detailed reconstruction of chronological changes in the palaeoenvironment. An important aspect of this study was also the first ever use of testate amoebae remains in the reconstruction of the Lublin Polesie environment. Findings from research on the Mytycze site for the first time confirmed that the beginning of the formation of the lake basin was similar to that reconstructed for all other lakes in the Lublin Polesie region investigated previously with multidisciplinary methods, and dates to the end of the late glacial of the Vistulian. The early phase of the peatland formation resulting from the shallowing of the lake was very long and lasted from the Subboreal period to the 15th century. The youngest phases with records of human impact are characterised by increased human pressure (intensified cultivation of cereals, buckwheat, legumes and brassica crops) after the Wieprz-Krzna Canal System was put into use, and intensified grazing in the vicinity of Lake Mytycze. This phase, dated to the 1970s, is followed by a marked increase in the water level, which was probably related to the supply of water to the dammed Lake Mytycze from Wieprz-Krzna Canal via Lake Dratów. Records in the upper part of the core indicate the return of Sphagnum spp., most likely due to the cessation of the use of hydraulic engineering structures and the renaturation of the lake and peatland ecosystem, which led to the appearance of valuable species of plants and birds. [ABSTRACT FROM AUTHOR]

Holocene streamflow was reconstructed for two rivers on Vancouver Island, British Columbia, Canada in 500-yr intervals. The San Juan River watershed is located on the wetter western side of the island, whereas the Koksilah River watershed is positioned on the drier eastern side. Both watersheds are forested. To reconstruct streamflow, temporal changes in precipitation (estimated using a pollen-based transfer function) and evapotranspiration were established for each watershed and integrated into a water balance model, calibrated using modern data. While seasonal streamflow variability was maintained throughout the Holocene, with greater flow in the winter relative to the summer, the amount of discharge has changed markedly through time. Lowest simulated flow occurred in the earliest Holocene, with low-flow conditions beginning earlier in the year and extending later into the fall. Such conditions may have inhibited salmon from using many of the smaller rivers in the region. Streamflow steadily increased throughout the early Holocene so that by ca. 6500 cal yr before present near-modern flow regimes were established. As climate changes in the future, the San Juan and Koksilah watersheds are expected to remain as pluvial hydroclimatic regimes, though with an extended season of low flow similar to conditions during the early Holocene. [ABSTRACT FROM AUTHOR]

Holocene slackwater deposits along the river channels were used to study the magnitude and frequency of the palaeofloods that occurred prior to gauged and historical data sets all over the world. Palaeohydrological investigations along the Shanxi-Shaanxi Gorge of the middle Yellow River, China, identified palaeoflood slackwater deposits (SWDs) at several sites along the cliffs bordering the river channel. The SWDs are intercalated within Holocene eolian loess-soil profiles and clastic slope deposits. The palaeoflood SWDs were differentiated from eolian loess and soil by the sedimentary criteria and analytical results including magnetic susceptibility and particle-size distribution, similar to the flood SWDs in 2012, which indicated that these well-sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. They have recorded the extraordinary palaeoflood events which occurred between 3200 and 3000 a BP as dated by the optically stimulated luminescence method in combination with pedostratigraphic correlations with the previously studied Holocene pedo-stratigraphy in the Yellow River drainage basin. Manning slope-area calculations estimate the peak discharged for these palaeoflood events to range from 43,290 to 49,830 m/s. The drainage area of the study site is 489,900 km. It is 2.0-2.5 times the largest gauged flood (21,000 m/s) that has ever occurred since 1934. These events also occurred on Yellow River tributaries, including the Weihe, Jinghe and Qishuihe Rivers. These flood events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climatic instability. This study provides important data in understanding the interactions between regional hydro-climatic systems and global change in semiarid and subhumid regions. [ABSTRACT FROM AUTHOR]

The processes and mechanisms of fluvial landform evolution, especially in the transitional zones between mountains and plains, are of great significance for predicting future regional sustainability and ecosystem stability in the basin. As a region of significant cultural and ecological importance, the transitional area between Taihang Mountain and North China Plain still has a limited understanding of the fluvial landform evolution. With detailed field surveys and 39 optically stimulated luminescence (OSL) ages of 14 sections, we reconstruct fluvial landform evolution in the southern piedmont of the Taihang Mountain since the late Pleistocene. The results show that two major fluvial processes occurred during 18–10 ka BP and 9–3 ka BP. Meanwhile, the late Pleistocene-Holocene can be divided into 5 intervals in the alluvial fan and floodplain areas, with corresponding ages of 3 ka BP, 9–3 ka BP, 10–9 ka BP, 18–10 ka BP, and before 20 ka BP, respectively. The results also indicate that the regional fluvial processes primarily result from climate change and tectonic activities, and secondarily result from sea level fluctuation. Additionally, the prehistoric settlement pattern was also shaped by the evolution of regional rivers. Our research is significant for understanding the evolution and mechanisms of fluvial landforms in transitional zones. • Holocene fluvial landscape evolution were reconstructed in southern Taihang. • Mechanism of fluvial landscape evolution in transitional area was revealed firstly. • Fluvial evolution was response to climate and structure activity, less associated with sea level. [ABSTRACT FROM AUTHOR]

The Nihewan-Huliu Basin was located in environmental transition zone, where was an important multicultural intersection in North China. The geographical and ecological transition was revealed by large scale vegetation changes, and the climatic changes had been estimated during the Holocene based on comprehensive comparison and analysis of the paleoenvironmental records surrounding the study area. Meanwhile, multicultural exchanges were represented based on the spatial distributions of archaeological sites in the Neolithic and Bronze Age. It is proposed that repeated multicultural exchanges and integration were inferential responses to the complex spatial-temporal evolution of the climate, ecology and geography near the Nihewan-Huliu Basin, especially, diverse cultures converged here from different directions after the abrupt cold events or serious climate changes in the mid-Holocene; the spatial connectivity with intermontane rivers and basins provided potential pathways for sustainable multicultural exchanges among mountains; the North-South movement of the forest boundary compelled the formation of steppe-forest and farming-pastoral ecotone here, and finally formed an active multicultural core region with integrated human civilization in North China. [ABSTRACT FROM AUTHOR]

Coastal evolution is influenced by past sea-level changes and resultant shifts from fluvial- to marine-dominant environments and the accompanying significant geochemical and isotopic changes in the water mass and sediments. We investigated the elemental and isotopic features of coastal sedimentary cores (27 m in length) from a small paleo-bay located on the southern coast of Korea to determine such geochemical variability and specify past changes in the bay environment and anoxic conditions and possible links to past climate changes. We analyzed total organic carbon (TOC), total sulfur (TS), their isotopes (δ13CTOC and δ34STS), and pyrite. The δ13CTOC values ranging from −25 to −19‰ (a proxy for terrestrial influence) were lower than average (−22.5‰) before 8300 cal yr BP and since 500 cal yr BP, while the intervening Early to Late Holocene showed higher δ13CTOC values, indicating a shallow coastal environment. The δ34STS values fluctuating between −35 and +5‰ resembled sedimentation rate change. Based on the changes in the ratios of TOC to TS (C/S ratios), sedimentation rate, and δ34STS, we found five possible periods with higher salinity and intensified anoxic conditions at millennial timescales: 8900–8200, 7950–6500, 5200–4300, 3500–2600, and 2000–1100 cal yr BP. These intensified anoxic conditions seem to have been influenced by increased air temperature and sea-surface temperature conditions, which could have intensified the intensity of thermal stratification (less ventilation and mixing) between surface and bottom waters and resultant anoxic conditions. [ABSTRACT FROM AUTHOR]

During the Early and Mid-Holocene significant changes in the ecology and socio-cultural spheres occurred around the Baltic Sea. Because of the underlying climatic changes and thus environmental alterations, the area was the scene for various cultural developments during the period under investigation. In the course of the melting of the glaciers at the end of the last Ice Age, isostatic and eustatic movements caused continual changes to the Baltic Sea basin. Changes in water level, however, affected not only the Early and Mid-Holocene coastlines, but also the whole Baltic Sea drainage system, including large lakes, rivers and watersheds in the hinterland were also dramatically impacted by these ecological changes. Prehistoric people were thus affected by changes in resource availability and reduction or enlargement of their territories, respectively. In order to evaluate the impact of changes in the water and land networks on the environment, resource availability, and human behaviour, and to reconstruct human responses to these changes, we pursue an interdisciplinary approach connecting environmental and archaeological research highlighted through different case studies. [ABSTRACT FROM AUTHOR]

The rock shelter of Tan Zoumaitek, Tassili-n-Ajjer, Central Sahara, Algeria, famous for its paintings of humans and mammals, is found to contain as well several pictures of objects that are most likely medusae. Ii is argued that these can be identified as the afrotropical Limnocnida tanganjicae GUNTHER. The duration of their isolation, after the end of the early Holocene humid period, may be contemporaneous (c. 8000 years) with that of the extant relicts of that species in Mauretania and Chad. These figures are the oldest images of a cnidarian currently known. [ABSTRACT FROM AUTHOR]

Human migration in response to past climate change has been recorded globally. The pastoralist Todas are believed to have colonised the higher elevations (>2000 m asl) of the Nilgiris, Western Ghats, India, after ∼2000 cal. yr BP. During the late Quaternary, climate-induced vegetation shifts in tropical montane forest-grassland mosaic of the Nilgiris have been well-documented using stable carbon isotopes and pollen, but there have been no corresponding investigations of human activity. We used several proxies to infer the human ecology of this region. Radiocarbon-dated (∼22,000 cal. yr BP to the present) peat from Sandynallah (2200 m asl) was used to reconstruct fire history, animal abundance, and human presence since the Last Glacial Maximum (LGM). While macro-charcoal records fires at the LGM, macro- and micro-charcoal indicate intense fire at ∼3500 cal. yr BP, coprophilous fungal spores indicate abundant herbivorous mammals, n-alkane signatures point to arid grassland vegetation, and steroid biomarkers show human faecal remains for the first time. We infer that a pastoralist people, most likely the Todas, migrated to the montane Nilgiris along with their buffaloes in response to prolonged or abrupt climate change in peninsular India ∼3500 cal yr BP or ~1500 years prior to what historical accounts assume. [ABSTRACT FROM AUTHOR]

The influence of sea-level and climate changes on the evolution of coastal floodplains is an important problem in fluvial geomorphology and geology. However, few studies have constructed detailed chronologies of floodplain evolution, and the influence of sea-level and climate changes at submillennial time scales is not clear. This study investigated the Holocene evolution of the floodplain in the Shiribeshi-Toshibetsu River lowland, Hokkaido, northern Japan, based on 13 auger cores, 15 radiocarbon ages, and 2 cross sections made using existing columnar sections. In the study area, peat beds 3–6 m thick in the uppermost Holocene sediments are underlain by fluvial sediment that mainly consists of sand beds resulting from crevassing or progradational avulsion. Age–elevation plots of the bases of these peat beds suggest that fluvial aggradation was continuous until peat formation began, which in turn suggests that peat beds began to form with the cessation of fluvial deposition. The chronology of floodplain sediments based on radiocarbon ages indicates that peatlands began to develop locally before ca. 6500 cal BP and became moderately widespread before 5600 cal BP. Peatlands then became more extensive after two periods of rapid expansion during ca. 5300–5000 and 4100–3900 cal BP. Comparison with sea-level and regional climate changes suggests that the initiation of these peat beds before 5600 cal BP was associated with the deceleration of sea-level rise at ca. 7000 cal BP. The two later periods of peatland expansion may have been strongly influenced by reduced fluvial activity due to decreased precipitation from a weakened East Asian summer monsoon. This interpretation suggests that floodplain evolution was controlled by sea-level and climate changes and that the response to climate change occurred at submillennial time scales. A comparison with the Ishikari lowland on Hokkaido showed that the two floodplains have slightly different histories, possibly because of differences in internal characteristics of the fluvial systems such as the number and size of tributary rivers, water discharge, and sediment supply, although their responses to sea-level and climate changes were similar. The fluvial response to sea-level and climate changes revealed in this study has implications for studies of the Holocene evolution of other coastal floodplains. [ABSTRACT FROM AUTHOR]

Extreme floods, with multi-century to millennia recurrence intervals, arise from a combination of antecedent watershed characteristics and unusual or rare atmospheric circulations that occur too infrequently to discern drivers from instrumental records. Few stream gauge records in the United States contain 100 years or more of annual peak flow data, meaning rare extreme floods are underrepresented in the peak flow population. We synthesized approximately 8,000 years of paleoflood hydrologic data from multiple studies and various landforms (floodplains, rock shelters, and caves) conducted in the Tennessee River Valley between Chattanooga, Tennessee, and Florence, Alabama, to examine Holocene flood variability. Extreme floods (>11,000 m3/s) clustered around ∼7,900, 6,000–4,900, and ∼1,000–80 cal yrs BP. More moderate floods occurred between 4,800 and 2,000 cal yrs BP. We compared flood variability in the Tennessee Valley to Holocene paleorecords available in North America. All periods of extreme flooding occurred during large-scale, abrupt climate transitions that lacked a distinct directionality of temperature change (i.e., warm to cool or cool to warm). Our findings indicate that extreme floods clustered in times when (1) warm-season precipitation increased, (2) abrupt increases in precipitation followed episodes of drought, and (3) the rate of change in the hydroclimate regimes was greater than the rate of morphological change in response to increased moisture, thus, exceeded geomorphic thresholds. Internal river basin factors such as drought-induced watershed changes and river morphological changes are key flood drivers that set the stage for flood response to changes in precipitation. Our findings suggest that anticipated changes to drought and precipitation intensity due to modern climate change may increase extreme floods, particularly for urban and regulated rivers not given the space for adjusting to higher precipitation variability. • Tennessee River extreme floods occurred ∼7,900, 6000–5,000, and ∼1000–80 cal yrs BP. • Extreme floods (≥Q 100) occurred during abrupt climate change (ACC) events. • We review hydrometeorological drivers of extreme floods during ACC. • Antecedent drought and increased summer rainfall drive extreme flood response. • Findings highlight the importance of geomorphic thresholds in flood risk management. [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]

Mollusk fauna is an important component of the Caspian Sea ecosystem alongside ostracods and diatoms. These faunal proxies are essential indicators of hydrological shifts reflecting global and regional climate changes. Adding lithological, geochemical, and geochronological (radiocarbon) data, we revealed paleogeographic events of different scales recorded in the sequence of the Rybachya core from the North Caspian Sea. Here, we present the reconstruction of Mangyshlak paleovalley sediments during the Holocene multi-stage Neocaspian transgression, reflecting global and regional climate changes varying in scale and direction. The determined age of paleovalley-fill sediments, 8070 ± 110 cal yr BP and 7020 ± 140 cal yr BP, suggests that sedimentation processes with extended warming and humidification started later and lasted longer than was assumed earlier. Biological proxies indicate quasi-cyclic variability and shifts from brackish to freshwater conditions throughout the studied interval. Rybachya core was obtained from the early Khvalynian deposits. The Mangyshlak flow formed the depression and eroded the late Khvalynian deposits, which we did not observe in the core structure. It possibly collapsed into paleodepression and acted as a host material for the freshwater lentic faunal association. During the Holocene, we detected a transition from a tranquil water regime to a more dynamic one during the paleovalley gradual filling, followed by marine conditions typical for the modern Caspian Sea. [ABSTRACT FROM AUTHOR]

Introduction: For future vegetation projections and conservation planning in grassland ecosystems, accurate estimates of past plant cover changes in grassland composition and their responses to the various driving factors are essential. This study quantitatively reconstructs the past regional plant cover in the Songnen grasslands (northeastern China) and explores the relative importance of climate, fire, and human activity on vegetation dynamics. Methods: For this purpose, the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model is applied to three pollen records from two areas, two in the center of the Songnen grasslands and one located in an area marginal to the grasslands. Results: Results from the most reliable REVEALS scenarios show that from the mid-Holocene, steppe (mean cover 40.6%) and dry steppe (mean cover 54.2%) alternately dominated the central part of the Songnen grasslands while the marginal grasslands were mainly characterized by alternating broadleaved forests (mean cover 26.3%), coniferous forests (mean cover 41.9%) and dry steppes (mean cover 30.1%). Discussion: By comparing the plant cover results with previous published regional climate, fire and human activity records, the results show that long term vegetation dynamics were mainly driven by East Asia Summer Monsoon (EASM) and the related precipitation variations, but was also affected by fire frequency and human activity. Moreover, vegetation evolution was sensitive to abrupt cooling events including the 4.2 ka BP and stacked ice-rafted debris (IRD) events; the change from steppe to dry steppe, for example, was driven by these abrupt climate changes. Fire events can alter the original vegetation stability allowing the vegetation to respond rapidly to climate changes while human activity merely has limited influence on vegetation changes. [ABSTRACT FROM AUTHOR]

Mangroves are among the world's most threatened ecosystems. Understanding how these ecosystems responded to past natural and anthropogenic drivers of ecological change is essential not only for understanding how extant mangroves have been shaped but also for informing their conservation. This paper reviews the available paleoecological evidence for Pleistocene and Holocene responses of Caribbean mangroves to climatic, eustatic, and anthropogenic drivers. The first records date from the Last Interglacial, when global average temperatures and sea levels were slightly higher than present and mangroves grew in locations and conditions similar to today. During the Last Glaciation, temperatures and sea levels were significantly lower, and Caribbean mangroves grew far from their present locations on presently submerged sites. The current mangrove configuration was progressively attained after Early Holocene warming and sea level rise in the absence of anthropogenic pressure. Human influence began to be important in the Mid-Late Holocene, especially during the Archaic and Ceramic cultural periods, when sea levels were close to their present position and climatic and human drivers were the most influential factors. During the last millennium, the most relevant drivers of ecological change have been the episodic droughts linked to the Little Ice Age and the historical developments of the last centuries. [ABSTRACT FROM AUTHOR]

The southeastern Tibetan Plateau is an important area of monsoonal maritime glaciation, and it serves as a watershed for several major Asian rivers, including the Brahmaputra River and the Lantsang River. Glacial activity is sensitive to climate change in this area. However, due to high annual ablation and accumulation in this region, ice cores over long time scales are difficult to retrieve. In addition, reconstructed glacial activity from moraine dates is usually discontinuous. Here, we use a sediment core retrieved from Laigu Lake, which is a proglacial lake located in the headwaters of the Parlung Zangbo River, the largest tributary of the Brahmaputra River, to reflect glacial activities over the last ~ 8000 years in this area. Samples of the sediment core were analyzed for magnetic susceptibility, XRF (X-ray florescence) scanned elemental concentration and grain size. The results indicated that the magnetic susceptibility and CPS (peak area counts per second) of strontium (Sr) could be used as proxies for glacial activity. The CPS of Sr and the magnetic susceptibility were lower and the glacial activity was weak before 4.3 cal ka BP. Expansion of the glaciers in this area began from 4.3 cal ka BP and continued to develop after ~ 3.3 cal ka BP. From 2.2 cal ka BP to 1.6 cal ka BP, the glaciers retreated substantially, followed by another development period until the onset of modern global warming. Based on our findings and other climate records, we concluded that glacial activity in the southeastern Tibetan Plateau areas was mainly influenced by Northern Hemisphere temperatures and summer insolation over a sub-orbital time scale, but did not respond to the Indian monsoon. [ABSTRACT FROM AUTHOR]

Carbonate minerals that precipitate from open-basin lakes can provide archives of past variations in the oxygen isotopic composition of precipitation (δ 18 O ppt ). Holocene δ 18 O ppt records from the circum- North Atlantic region exhibit large fluctuations during times of rapid ice sheet deglaciation, followed by more stable conditions when interglacial boundary conditions were achieved. However, the timing, magnitude, and climatic controls on century to millennial-scale variations in δ 18 O ppt in northeastern North America are unclear principally because of a dearth of paleo-proxy data. Here we present a lacustrine sediment oxygen isotope (δ 18 O) record spanning 10,200 to 1200 calendar years before present (cal yr BP) from Cheeseman Lake, a small, alkaline, hydrologically open lake basin located in west-central Newfoundland, Canada. Stable isotope data from regional lakes, rivers, and precipitation indicate that Cheeseman Lake water δ 18 O values are consistent with the isotopic composition of inflowing meteoric water. In light of the open-basin hydrology and relatively short water residence time of the lake, we interpret down-core variations in calcite oxygen isotope (δ 18 O cal ) values to primarily reflect changes in δ 18 O ppt and atmospheric temperature, although other factors such as changes in the seasonality of precipitation may be a minor influence. We conducted a series of climate sensitivity simulations with a lake hydrologic and isotope mass balance model to investigate theoretical lake water δ 18 O responses to climate change. Results from these experiments suggest that Cheeseman Lake δ 18 O values are primarily controlled by temperature and to a much lesser extent, the seasonality of precipitation. Increasing and more positive δ 18 O cal values between 10,200 and 8000 cal yr BP are interpreted to reflect the waning influence of the Laurentide Ice Sheet on atmospheric circulation, warming temperatures, and rapidly changing surface ocean δ 18 O from the input of glacial meltwater into the western North Atlantic Ocean. The increasing trend is interrupted by abrupt negative δ 18 O cal anomalies at 9700 cal yr BP, associated with a transition to colder sea surface temperatures (SSTs) in the Labrador Sea and renewed Laurentide Ice Sheet retreat, and at 8500 cal yr BP that coincides with a well-established cooling event in the circum-North Atlantic region. After 8000 cal yr BP, δ 18 O cal values gradually decrease until 4300 cal yr BP, which reflects a cooling trend related to declining Boreal summer insolation and lower sea surface temperatures in the western North Atlantic Ocean. δ 18 O cal becomes slightly more positive from 4300 to 2500 cal yr BP and thereafter declines to the most negative values of the late Holocene by 1200 cal yr BP. The middle to late-Holocene transition at ~ 4300 cal yr BP corresponds with a shift to wetter conditions in Newfoundland that is also seen in other paleo-proxy records from the region. The discordance between the Cheeseman Lake δ 18 O cal record and declining insolation could in part reflect warmer temperatures or an increase (decrease) in warm (cold) season precipitation. Considering evidence from other paleo-records in Newfoundland, we suggest this transition resulted from a change in synoptic scale atmospheric circulation to a configuration similar to the positive mean state phase of the Pacific-North American pattern. Proxy evidence from Cheeseman Lake therefore supports the idea that a substantial climatic change occurred during the middle to late-Holocene transition (between ~ 5000 to ~ 4000 cal yr BP) in northeastern North America. [ABSTRACT FROM AUTHOR]

Despite the importance of ancient DNA for understanding human prehistoric dispersals, poor survival means that data remain sparse for many areas in the tropics, including in Africa. In such instances, analysis of contemporary genomes remains invaluable. One promising approach is founder analysis, which identifies and dates migration events in non-recombining systems. However, it has yet to be fully exploited as its application remains controversial. Here, we test the approach by evaluating the age of sub-Saharan mitogenome lineages sampled outside Africa. The analysis confirms that such lineages in the Americas date to recent centuries—the time of the Atlantic slave trade—thereby validating the approach. By contrast, in North Africa, Southwestern Asia and Europe, roughly half of the dispersal signal dates to the early Holocene, during the "greening" of the Sahara. We elaborate these results by showing that the main source regions for the two main dispersal episodes are distinct. For the recent dispersal, the major source was West Africa, but with two exceptions: South America, where the fraction from Southern Africa was greater, and Southwest Asia, where Eastern Africa was the primary source. These observations show the potential of founder analysis as both a supplement and complement to ancient DNA studies. [ABSTRACT FROM AUTHOR]

Mediterranean fluvial hydrology is characterised by decadal-to-multi-centennial length wet and dry episodes with abrupt transitions related to changes in atmospheric circulation. Since the mid-1990s site-based flood chronologies from slackwater deposits in bedrock rivers and regionally aggregated flood histories from alluvial deposits have developed increasingly higher resolution chronological frameworks, although regional coverage is still uneven. This paper analyses the spatial and temporal distribution of extreme Holocene hydrological events recorded in fluvial stratigraphy in the Iberian Peninsula (Spain and Portugal), southern France, southern Italy, Northern Africa (Morocco and Tunisia) and eastern Mediterranean (Greece, Crete, Turkey, Cyprus and Israel). This study constitutes the most comprehensive investigation of Holocene river flooding ever undertaken in the Mediterranean and is based on the analysis of 515 14 C and 53 OSL dates. It reveals that flood periods in different regions cluster into distinct time intervals, although region-wide flooding episodes can be identified at 7400–7150, 4800–4600, 4100–3700, 3300–3200, 2850–2750, 2300–2100, 1700–1600, 1500–1400, 950–800, ca. 300, 200–100 cal. BP. Periods with more frequent floods in the western Iberian region coincide with transitions to cool and wetter conditions and persistent negative NAO mode. In Northern Africa increased flood frequency coincides with periods of generally drier climate, while in the eastern Mediterranean there is a higher incidence of extreme flood events under wetter conditions. Our meta-data analysis identifies an out-of-phase pattern of extreme events across the Mediterranean over multi-centennial timescales, which is particularly evident between the western Iberian and eastern Mediterranean regions. This centennial-to-multi-centennial see-saw pattern in flooding indicates that bipolar hydroclimatic conditions existed in the Mediterranean during the Holocene. [ABSTRACT FROM AUTHOR]

Seabird population size is intimately linked to the physical, chemical, and biological processes of the oceans. Yet, the overall effects of long-term changes in ocean dynamics on seabird colonies are difficult to quantify. Here, we used dated lake sediments to reconstruct ~10,000-years of seabird dynamics in the Northwest Atlantic to determine the influences of Holocene-scale climatic oscillations on colony size. On Baccalieu Island (Newfoundland and Labrador, Canada)--where the world's largest colony of Leach's storm-petrel (Hydrobates leucorhous Vieillot 1818) currently breeds--our data track seabird colony growth in response to warming during the Holocene Thermal Maximum (ca. 9000 to 6000 BP). From ca. 5200 BP to the onset of the Little Ice Age (ca. 550 BP), changes in colony size were correlated to variations in the North Atlantic Oscillation (NAO). By contrasting the seabird trends from Baccalieu Island to millennial-scale changes of storm-petrel populations from Grand Colombier Island (an island in the Northwest Atlantic that is subjected a to different ocean climate), we infer that changes in NAO influenced the ocean circulation, which translated into, among many things, changes in pycnocline depth across the Northwest Atlantic basin where the storm-petrels feed. We hypothesize that the depth of the pycnocline is likely a strong bottom-up control on surface-feeding storm-petrels through its influence on prey accessibility. Since the Little Ice Age (LIA), the effects of ocean dynamics on seabird colony size have been altered by anthropogenic impacts. Subsequently, the colony on Baccalieu Island grew at an unprecedented rate to become the world's largest resulting from favorable conditions linked to climate warming, increased vegetation (thereby nesting habitat), and attraction of recruits from other colonies that are now in decline. We show that although ocean dynamics were an important driver of seabird colony dynamics, its recent influence has been modified by human interference. [ABSTRACT FROM AUTHOR]

Degradation of coastal environments is an issue that many areas in Europe are facing. In the present work, an ancient coastal lake wetland is investigated, the so-called Lake Lerna in NE Peloponnese, Greece. The area hosted early agricultural populations of modern Greece that started modifying their environment as early as the early–middle Neolithic. Two drill cores in the area of the ancient lake were analysed to establish the sedimentological succession and the depositional environments using sub-fossil assemblages (molluscs and ostracods). Three lithological and faunal units were recovered, the latter being confirmed by the statistical ordination method (non-metric multidimensional scaling). The usage of sub-fossil mollusc species for the first time in the region enriched the dataset and contributed significantly to the delimitation of the faunas. These consist of environments characterised by various levels of humidity (from stagnant waters to freshwater lake) and salinity, with ephemeral intrusions of salt water to the lake, documented by mollusc and ostracod populations. We conclude that the lake and its included fauna and flora were mostly affected by climatic fluctuations rather than human intervention in the area. [ABSTRACT FROM AUTHOR]

We investigated the population dynamics of a highly clonal marine angiosperm, Cymodocea nodosa, in the eastern Mediterranean Sea, to identify the historical dynamics, demography, and connectivity of the species in the area. Eighteen microsatellite loci were used in conjunction with coalescent methods to investigate the genetic structure and demographic history of C. nodosa meadows. Approximate Bayesian computation (ABC) modeling was used to examine the pattern of divergence over time in the context of environmental change over the course of the Quaternary period. ABC analysis revealed an initial split of the C. nodosa populations between the north‐western, northern, and north‐eastern Aegean Sea during the Pleistocene epoch, followed by a more recent divergence of the north‐western population and the central‐western part of the Aegean Sea. According to the results, the most parsimonious historical scenario is that of a pervasive genetic signature of the effects of the drop in sea level during the Pleistocene epoch. This scenario supports the isolation of the north‐western, north, and north‐eastern area, and the subsequent recolonization after post‐glaciation sea level rise that may explain the north‐western differentiation as well present‐day detected dispersion of C. nodosa. [ABSTRACT FROM AUTHOR]

Holocene changes in fine-grained sediment supplies to the East China Sea outer shelf were uncovered, through the mineralogical and geochemical analysis of Core B3 in the East China Sea Distal Mud (ECSDM). Based on the lithology, accelerator mass spectrometry (AMS) 14C dating, and sea-level change, Core B3 can be divided into two major units: transgressive stage (Unit 1: 12.5–6.8 kyr) and highstand stage (Unit 2: 6.8–0 kyr). Significant discrepancy of dolomite/calcite ratio in the fine fractions (<16 µm) of Changjiang (dolomite/calcite = 3:1) and Huanghe (dolomite/calcite = 1:22) sediments was used as a new uniqueness provenance tracer to distinguish these two riverine sources. Both of the dolomite/calcite ratio and rare earth elements fractionation parameters in the fine-grained sediment indicated distinct provenance shifts of Core B3 during the Holocene. Unit 1 of Core 3 (12.5–6.8 kyr) mainly consists of the reworked and resuspension sediments of the East China Sea shelf during the Holocene transgression, while Unit 2 sediments (6.8–0 kyr) are most likely sourced from the Changjiang and Huanghe. Moreover, mixing curves of dolomite/calcite ratio reveal that the ECSDM continuously received the Changjiang sediment since 6.1 kyr with notable fluctuations, whereas the Huanghe sediment supply began in 6.8 kyr but abruptly stopped during 4.2–0.8 kyr and then appeared again since 0.8 kyr. Temporal changes of the Changjiang and Huanghe fine-grained sediment contribution to the ECSDM are closely related to the formation of modern oceanic circulation system since 6.8 kyr (shelf sea-level change), the ‘4.2 kyr’ climate event, and the followed transition to cold and dry climate condition in the northeastern China (global climate change), as well as the artificial shift of lower Huanghe course in ad 1128 in the war against invasion of the northern nomadic nation (human activities). [ABSTRACT FROM AUTHOR]

We present new high‐resolution pollen records combined with palaeoceanographic proxies from the same samples in deep‐sea cores SHAK06‐5K and MD01‐2444 on the southwestern Iberian Margin, documenting regional vegetation responses to orbital and millennial‐scale climate changes over the last 28 ka. The chronology of these records is based on high‐resolution radiocarbon dates of monospecific samples of the planktonic foraminifera Globigerina bulloides, measured from SHAK06‐5K and MD01‐2444 and aligned using an automated stratigraphical alignment method. Changes in temperate and steppe vegetation during Marine Isotope Stage 2 are closely coupled with sea surface temperature (SST) and global ice‐volume changes. The peak expansion of thermophilous woodland between ~10.1 and 8.4 cal ka bp lags behind the boreal summer insolation maximum by ~2 ka, possibly arising from residual high‐latitude ice‐sheets into the Holocene. Rapid changes in pollen percentages are coeval with abrupt transitions in SSTs, precipitation and winter temperature at the onset and end of Heinrich Stadial 2, the ice‐rafted debris event and end of Heinrich Stadial 1, and the onset of the Younger Dryas, suggesting extrinsically forced southwestern Iberian ecosystem changes by abrupt North Atlantic climate events. In contrast, the abrupt decline in thermophilous elements at ~7.8 cal ka bp indicates an intrinsically mediated abrupt vegetation response to the gradually declining boreal insolation, potentially resulting from the crossing of a seasonality of precipitation threshold. [ABSTRACT FROM AUTHOR]

Greenock Swamp wetland complex is one of few remaining natural wetlands in the Great Lakes region and, at 89 km2 in areal extent, is currently the largest hardwood swamp in southern Ontario, Canada. We present here pollen and sediment records from a kettle hole (Schmidt Lake) and adjacent Thuja occidentalis swamp to reconstruct regional paleoclimate and vegetation history, and to assess the timing and development of the swamp ecosystem and associated carbon stocks. Pollen-inferred paleoclimate reconstructions show the expected warming in the Early Holocene, and indicate the Mid-Holocene initiation of lake-effect snow. This enhanced snowfall may have maintained high water tables in the adjacent wetland since ca. 8300 years ago, promoting the establishment of a swamp dominated by Thuja occidentalis. Carbon accumulation rates in a >2-m-long peat core collected from a Thuja occidentalis stand adjacent to Schmidt Lake are 30-40 g C/m2/yr, which is higher than the average of northern high-latitude peatlands. Using topographic and hydrological parameters, we estimated that mean swamp peat thicknesses could exceed 2m. Thus, this study encourages future investigations on temperate swamps from the perspective of hitherto underestimated Holocene carbon sinks and shows the importance of regional hydroclimate in supporting swamp ecosystems. [ABSTRACT FROM AUTHOR]

Climate variability has probably affected the frequency and distribution of debris flows and snow avalanches throughout the Holocene. In this paper, we reconstruct the Holocene history of debris flows and snow avalanches by investigating outcrops in colluvial fans surrounding lake Anestølsvatnet in western Norway and sediment cores penetrating the lake-floor deposits. We made a detailed map of the surface deposits around the lake. The formation of a large end moraine that dams the lake was radiocarbon dated to 10,200-10,800 cal. yr BP, and correlates to the Erdalen event, a Preboreal glacial oscillation. There are colluvial fans and debris-flow paths and snow-avalanche paths eroded on the steep slopes around the lake. On the western slopes, the fans are dominated by snow avalanches, and on the eastern slopes by debris-flow activity. Three of the lake cores were taken distal to the largest avalanche fan on the western slope, Storeskreda ('Storeskreda' means 'the big landslide'). Clasts > 2 mm in the lake sediments are interpreted as traces of snow avalanches and sorted sand layers as being derived from debris flows. Loss-on-ignition and magnetic susceptibility measurements document an increased silt content in the lake sediments after c. 6000 cal. yr BP, probably due to the reappearance of local glaciers in the area. Our combined data from the onshore outcrops/pits and lake sediments shows almost continuous snowavalanche activity and debris-flow activity throughout the last 10,000 years. However, there may have been an increase in the snow-avalanche activity over the last 5000 years. [ABSTRACT FROM AUTHOR]

Lake sediments are important archives of past climate variability and lake responses to climate. In order to accurately infer past climates, it is necessary to understand, and account for, the ecological processes that affect the record of indicators preserved in lake sediment. This is particularly the case with respect to the concentration of carbon and nitrogen (TOC, TN, and calculated C:N), and the stable isotope composition of organic matter preserved in lake sediments. These are common, yet ambiguous, tracers of environmental change. Ideally, palaeoenvironmental reconstructions using the concentration and isotope composition of organic matter should be grounded in a detailed understanding of the sources of the organic material. This study documents the history and evolution of Blue Lake, an environmentally and culturally important oligotrophic, groundwater window lake on North Stradbroke Island, Queensland, Australia. We utilise organic matter δ13C, TOC, TN, and C:N from a 2.4 m sediment core with a basal age of 7.5 cal kyr BP, to investigate changing organic matter sources as a measure of the climate sensitivity of Blue Lake. This interpretation is supported by data from contemporary algae, aquatic and terrestrial plants, and catchment soils. We show that lake nutrient dynamics drove an increase in algal biomass at 4.2 cal kyr BP. This change coincides with a widely documented intensification of the El Niño-Southern Oscillation, which we infer to have influenced lake nutrient concentrations by reducing groundwater throughflow. Climatic changes resulted in marked changes in lake primary productivity, despite relatively little turnover of the lake diatom flora and catchment vegetation. This suggests that south-east Queensland dune lakes are sensitive to climate changes and helps to refine past and future palaeoclimate research using sediments from these lakes. It also indicates that increased nutrient concentrations in Blue Lake may result from projected changes in 21st Century climate. [ABSTRACT FROM AUTHOR]

Lakes provide high-sensitivity and high-resolution documents and evidence, which are required for studying climatic changes and sedimentary environments at the global level. Furthermore, aeolian deposits in lacustrine environments, because of recording drought periods and dust storms, are valuable archives of paleoenvironmental conditions. In the present study, besides collecting the previous data, it was attempted to sample three intact sedimentary cores with the maximum depth of 7.3 m and total depth of above 20 m, from the sediments of the lakebed by auger. Sedimentary facies were separated based on their color, grain size; sedimentary composition, grain shape, and type of evaporate minerals. The existence of brown-colored coarse-grained pneumatic sand particles during the early to mid-Holocene period (8.2 ka BP) indicated the occurrence of intense storms in Sistan Basin. Sequence of the fine- and very fine-grained pneumatic sands at the depth of 2.5 m represented the presence of the winds similar to the current "120 day winds" in Sistan plain. Moreover, in this study, two major drought periods (8.2 and 4.5 ka BP) were identified in Holocene sediments of the lakebeds of Hamun-e-Helmand and Hamun-e-Sabari, which indicated drying and expansion of the aeolian sediments on Hamun's lakebed. [ABSTRACT FROM AUTHOR]

Stand-scale gap-phase dynamics is generally viewed as the main driver of development in mesic deciduous forests of the temperate biome. Soil charcoal of temperate forests in eastern North America are unnoticed in most surveys, thus explaining why fire is undervalued as a driver of forest succession. The extent to which gap-phase, fire, or other processes are responsible for the regeneration and maintenance of mesic deciduous forests is unknown because paleoecological evidence is lacking. We tested the fire-driven succession hypothesis on the development of this major forest type. Based on charcoal 14C dates of two sites, 44 and 55 fires occurred since early Holocene, with a mean interval of 170 to 215 years. The vegetation of both sites followed comparable post-glacial trajectories consisting of three distinct periods. Conifers dominated the two first periods during 5200–6000 years and were replaced by hardwoods–conifers over the last 3500 years. The first period was represented by boreal conifers, whereas the second period, dominated by white pine (Pinus strobus) forests, persisted during 3000–4300 years. The third period marked the development of hardwood (sugar maple, Acer saccharum) forests. Fires occurred continuously on the sites since early Holocene likely under dry conditions during the conifer periods and cooler and moister conditions during the hardwood–conifer period. Recurrent fires appear with climate as key drivers of the long-term dynamics of several temperate forests in eastern North America. Similar studies on other temperate forests should be pursued to test the hypothesis of climate–fire interactions influencing tree composition change. [ABSTRACT FROM AUTHOR]

Paleoperspectives of climate provide important information for understanding future climate, particularly in arid regions such as California, where water availability is uncertain from year to year. Here, we present a record from Barley Lake, California, focusing on the interval spanning the Younger Dryas (YD) to the early Holocene (EH), a period of acute and rapid global climate change. Twelve radiocarbon dates constrain the timing between 12.9 and 8.1 ka. We combine a variety of sediment analyses to infer changes in lake productivity, relative lake level, and runoff dynamics. In general, the lake is characterized by two states separated by a <200-year transition: (1) a variably deep, lower-productivity YD lake; and (2) a two-part variably shallow, higher-productivity EH lake. Inferred EH winter-precipitation runoff reveals dynamic multidecadal-to-centennial-scale variability, in agreement with the EH lake-level data. The Barley Lake archive captures both hemispheric and regional signals of climate change across the transition, suggesting a role for both ocean-atmosphere and insolation forcing. Our paleoperspective emphasizes California's sensitivity to climate change and how that change can generate abrupt shifts in limnological regimes. [ABSTRACT FROM AUTHOR]