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In this paper, a new decadal resolution stalagmite δ18O record covering 10.4–6.5 ka BP from Kulishu cave in Beijing, north China is presented in combination with the published stalagmite δ18O record covering 10.4–14.0 ka BP in the same cave. Five significant monsoon collapses were identified around 11.5, 11.0, 10.0, 9.4, and 8.2 ka BP as well as three smaller ones around 10.3, 9.0, and 8.6 ka BP. The weak monsoon episodes around 8.6 and 8.2 ka BP form the two-step structure of the 8.2 ka event. All monsoon collapses, coeval with the cooling in northern high-latitude records, are correlated with Lakes Agassiz-Ojibway outbursts. Thus, our data support the idea of freshwater forcing of abrupt climate anomalies during the early Holocene. Nevertheless, the decreased irradiance together with freshwater outburst may account for the 9.2/9.3 ka event, which is expressed more significantly in low-latitude records. [ABSTRACT FROM AUTHOR]

The vast Dongting Lake in the middle Yangtze River basin, China, was occupied by Chinese Neolithic settlements starting 10 000 years ago, and rice cultivation there is probably the earliest in the world. The numerous Neolithic settlements identified by previous archaeological surveys represent the five major Neolithic cultural stages, i.e. the Pengtoushan (9000–7900 cal. yr BP), Zaoshixiaceng (7900–6800 cal. yr BP), Daxi (6800–5500 cal. yr BP), Qujialing (5500–5000 cal. yr BP), and Shijiahe (5000–4000 cal. yr BP). Using sedimentological and geoarchaeological approaches, this paper analyses the drivers of basin-scale settlement relocation in relation to lake-level fluctuations and monsoon climate variations in the Holocene. The relocation of Neolithic sites around the lake shoreline and on the adjacent floodplain, together with radiocarbon-dated stratigraphy, clearly indicates that the shape of the lake basin was an incised and elongated valley occupied by a lake in the early Holocene, which became a broader and shallower depression in the mid to late Holocene. The established lowest habitable base of the settlements positioned on the lake shore assists reconstruction of the change in lake level from 22 m at 9000 cal. yr BP to 26 m at 5500–4000 cal. yr BP, although higher and lower lake levels occurred during the intervening cultural stages. The pollen spectra reveal a warming trend throughout the Holocene with at least four major temperature cycles, driven by monsoon variations between temperate- and warm-humid conditions. In the early Holocene the climate changed from cool-dry to warm-humid, and this played a key role in developing the earliest Pengtoushan culture in the region. Subsequent climate fluctuations fit well with the advance and retreat of the lake shore, also coevally with Neolithic site movements in the lake region. In this study we show how geoarchaeological evidence can be used in environmental reconstruction during the Holocene. [ABSTRACT FROM AUTHOR]

This paper reconstructs the evolutionary history of the Pearl River delta over the last 9000 years and investigates land-sea interaction in a large deltaic complex which formed under the influence of Asian monsoon climate. Specifically, this research examines the delta evolution in the context of three driving mechanisms: (1) rising sea level that influences the available accommodation space, (2) fluvial discharge as influenced by monsoon climate and (3) human activities that alter sedimentation within the deltaic system. Results reveal that the formation of deltaic sequences was initiated as a consequence of rapid sea-level rise between 9000 and 7000 cal. yr BP. The rate of sea-level rise slowed down markedly around 7000 cal. yr BP and sedimentation switched from transgressive to regressive. Initially, both the progradation of the delta plains near the apex and aggradation of delta front sedimentation in the central and lower parts of the receiving basin were fast owing to strong monsoonal-driven runoff. The progradation rate gradually slowed down between 6800 and 2000 cal. yr BP as monsoonal-driven runoff weakened. Rapid shoreline advances during the last 2000 years were the result of significantly increased human activities, a practice that trapped sediments in the encircled tidal flats along the front of delta plains. The evolutionary history of the Pearl River delta demonstrates the interplay between the three driving mechanisms. [ABSTRACT FROM AUTHOR]

The paper explores the use of Resilience Theory to provide an improved theoretical framework for the analysis of socio-ecological interactions over decadal—millennial timescales. It identifies landscape system behaviour through analysis of proxy records for land use, erosion and monsoon intensity over the past 3000 years in the Erhai lake-catchment system, Yunnan, SW China. Analysis of the records shows the possibility of alternative steady states in the landscape, as expressed by the relationship between land use and erosion. In particular, a period of agricultural expansion ~1400 cal. yr BP triggered rapid gully erosion that led to the formation of an eroded landscape state that has existed since ~800 cal. yr BP to the present day. Comparison of detrended time-series data suggests that over 3000 years erosion and land use should be considered 'slow' processes relative to the 'faster' monsoon intensity and flooding. In the past, the effects of high monsoon variance on flooding have been suppressed by paddy farming and the maintenance of terraced field systems. Mapping the Adaptive Cycle on to the millennial record of land use and erosion suggests that the modern landscape may be approaching a 'conservation' phase characterized by minimum resilience. Such 'historical profiling' of modern landscapes offers a new dimension for hypothesis testing, for the development and testing of simulation models and for the creation of appropriate management strategies. [ABSTRACT FROM AUTHOR]

A comprehensive and integrative view of East Asian monsoon evolution during the Holocene is still under debate, and additional high-resolution proxy records from climatically sensitive locations are requisite to solve this complex issue. In this paper, we present three well-dated mud/peat cores from a paleo-pingo depression in the Sanjiang Plain, a climatically sensitive region to monsoon variation, to reveal the paleoenvironmental history of the wetland and discuss the regional impacts from monsoon evolution. A paleolake developed in the study area before 5.5 ka BP, and a peatland initiated thereafter consequent upon the gradual shrinking of the paleolake. This transition lasted until 4.5 ka BP, when the paleolake changed entirely to a wetland. Considering the prevalent monsoon climate in the Sanjiang Plain, we suggest that the lake-to-wetland transition from 5.5 to 4.5 ka BP indicates a rapid decline of the East Asian summer monsoon in addition to autogenic basin infilling processes. Such a remarkable monsoon weakening event has been documented across northern China, and we associate this with ocean–atmosphere interactions throughout low-latitude regions. [ABSTRACT FROM AUTHOR]

The Northeastern China involves complex interactions between the East Asian summer monsoon (EASM) circulation and the polar climate system, and plays a significant role as the bridge communicating low- and high-latitude climatic processes. High-resolution multi-proxy analysis of a robust accelerator mass spectrometry (AMS) 14C dated lacustrine sediment core recovered from Jingpo Lake in Northeastern China provides a detailed history of EASM variability and vegetation changes since ~5100 cal. yr BP. The period from ~5100 to 3600 cal. yr BP was characterized by the highest pollen percentages of Quercus, Ulmus, Juglans and Corylopsis; low Md (median grain size diameter); and high δ13Corg values, reflecting a relatively warm and humid period. The period between ~3600 and 2100 cal. yr BP is characterized by high Md and low δ13Corg values, and a rapid increase in pollen percentages of herbs, indicating cool and dry climatic conditions. From ~2100 to 150 cal. yr BP, a gradual increase in δ13Corg values and low Md values, and a rapid increase in Carpinus, Juglans and Corylopsis pollen percentages was observed, indicating climate change towards warmer and wetter conditions. After ~150 cal. yr BP, the highest values of total organic carbon mass accumulation rate (TOC-MAR), total nitrogen mass accumulation rate (TN-MAR) and magnetic susceptibility suggesting that the Jingpo Lake region has been severely affected by human activities. The EASM variability in Northeastern China during the mid- to late Holocene shows trends similar to EASM records in China. Furthermore, our findings indicate that the variability of the EASM during the mid- to late Holocene on the multi-decadal to centennial scale was forced by changes in both solar output and oceanic–atmospheric circulation interaction. [ABSTRACT FROM PUBLISHER]

The last glacial–interglacial climate transition in East Asia was characterized by an intensified monsoon, but knowledge about hydrological responses at a regional scale during this transitional period is limited. Here we provide a novel lipid-based paleohydrological record for this period from the Dajiuhu peat deposit, central China. High water levels and persistent wet conditions during the Younger Dryas (12.5–11.6 ka) and the early Holocene (10.5–9.9 ka) were inferred on the basis of enrichments of sterenes, a group of unstable intermediate diagenetic products derived from biogenic sterols that are most likely preserved under a waterlogged peatland surface. These two wet intervals were accompanied by temperature decreases indicated by an increase in pollen abundance from cold favoring conifer trees and a decrease in total hardwood tree pollen. This cold and wet climate pattern, which is different from the concordant cold-dry pattern documented in north China, was probably caused by the regional influence of the western Pacific subtropical high on the residence time of the Meiyu rainband in the middle and lower reaches of the Yangtze River Valley. [ABSTRACT FROM AUTHOR]

It has been suggested that late-Holocene human activities caused the increase in atmospheric methane (CH4) concentration that otherwise would have been a naturally decreasing trend. As one of the places where rice farming originated, China has been considered to play a significant role in pre-industrial changes in atmospheric CH4 concentrations. To establish the climatic context since the first rice cultivation and to evaluate the relative roles of monsoon climate and rice cultivation on late Holocene CH4 rise, we synthesized climate data from China to examine the Holocene trends in monsoon precipitation. The results show high monsoon rainfall from 10,000 to 7000 years ago, and declining precipitation in the late Holocene as shown by most reconstructions. The decreasing trend in monsoon precipitation is consistent with that in other north tropical monsoon regions, and is opposite to the trend in CH4 concentrations. After ruling out several other natural factors and estimating CH4 emissions from early rice farming, we conclude that the late-Holocene methane increase has been significantly influenced by the expansion of early rice paddy fields during the period of declining monsoon precipitation. [ABSTRACT FROM AUTHOR]

Understanding the mid-Holocene dynamics of the East Asian monsoon (EAM) is integral to improving models of the Holocene development of the global climate system. Here we reconstruct the mid-Holocene EAM history from the Pearl River estuary, southern China, using bulk organic carbon isotopes (δ13C), total carbon to total nitrogen (C/N) ratios and total organic carbon (TOC) concentration. Sedimentary δ13C, C/N and TOC are potentially good indicators of changes in monsoonal precipitation strength. Sediments buried during a period of high precipitation exhibit a high proportion of terrigenous material, and have low δ13C and high C/N, and vice versa during a period of low precipitation. Results suggest a general decreasing trend in monsoonal precipitation from 6650 to 2150 cal. yr BP because of the weakening Northern Hemisphere insolation most likely related to the current precession circle. Superimposed on this trend are apparent dry–wet oscillations at centennial to millennial timescales most likely in response to solar activity. Mismatches between our δ13C record and results from the Dongge Cave in southern China at millennial timescales may indicate that the δ13C from the Pearl River estuary reveals changes in precipitation over a broader area than the δ18O from Dongge Cave. [ABSTRACT FROM AUTHOR]

A high-resolution record of Holocene environmental and climatic change in the Balikun area was reconstructed from a sediment core from the Lake Balikun. Multiproxy data show that the climate was extremely arid during the early Holocene (before 8.6 cal. ka BP). Moisture began to increase after 8.6 cal. ka BP and the climate was humid between 7.9 and 4.3 cal. ka BP. A significant dry event occurred around 4.3–3.8 cal. ka BP. The climate became generally wet during the late Holocene (after 3.8 cal. ka BP). The Holocene pollen and geophysical records do not indicate a wet early Holocene, making it evident that there was no early-Holocene humid period associated with peak Asian monsoon strength. Regional comparisons indicate that this region has a different pattern of Holocene environmental and climatic change from the Asian monsoonal area and south Siberia. [ABSTRACT FROM AUTHOR]

A relatively cold period, the ‘Little Ice Age’ (LIA), just prior to the current warm period, has been documented from many regions of the globe. However, hydrological changes (wet/dry conditions) during the LIA appear to be very different across different climatic regimes, suggesting that the position, strength and/or pattern of atmospheric circulation could have changed significantly in the past. Therefore, paleohydrological studies may have some implications for potential future hydrological changes in an anticipated warming world. In this study, we investigated hydrological changes over the last ~800 years in the arid Tarim Basin, northwestern China. We used carbon isotopes of plant remains (mainly leaves) from a 10.5 m long aeolian sand sediment section to evaluate changes in dry/wet conditions. The average value of carbon isotopes of plant remains during the LIA period (~AD 1490 to 1890) is −26.0‰, ranging from −28.2‰ to −23.6‰, much lower than values before (average of −24.3‰, from −25.5‰ to −22.4‰) and after this period (average of −22.8‰, −24.6‰ to −21.6‰). Although other environmental factors could also affect carbon isotopes to some degree, such consistent, large negative isotopic excursions of up to 6‰ strongly suggest a wetter climatic condition in the study area at that time, which is also consistent with two silty clay layers, indicating a wet depositional environment, found around AD 1560 and AD 1625 during the LIA period. This inference is consistent with previous studies suggesting a relatively wet period during the LIA in the Tarim Basin and possibly extending to the western central Asia region, but appears to be opposite to hydrological changes in regions that are today dominated by Asian monsoon systems. This pattern of regional hydrological changes may be related to possible changes in the trajectory or strength of the westerlies and/or the orographic effect in this region, as previous studies suggested. [ABSTRACT FROM PUBLISHER]

High-resolution oxygen isotope (δ18O) profiles of six stalagmites from Sanbao Cave in Hubei province, central China, established with 1413 oxygen isotope data and 65 230Th ages, provide a continuous history of East Asian Summer Monsoon (EASM) intensity for the period from 13-0.2 thousand years before present (ky BP, relative to AD 1950). The δ18O record includes four distinct stages in the evolution of the EASM: (1) an abrupt transition (∼11.5 ky BP) into the Holocene; (2) a period of gradual increase in monsoon intensity (11.5-9.5 ky BP); (3) the maximum humid period (9.5-6.5 ky BP); and (4) a period of gradual decline in monsoon intensity (6.5-0.2 ky BP). Comparison of Sanbao with regional records of comparable resolution reveals that the timing of the beginning and end of the Holocene Optimum (as defined by the minimum in δ18O) was similar in the Indian and East Asian monsoon systems. This supports the idea that shifts in the monsoon tied to shifts in the mean position of the Inter-Tropical Convergence Zone (ITCZ) may control monsoon intensity throughout the entire low-latitude region of Asia on orbital timescales. This observation also supports the idea that the fluctuations in δ18O recorded across southern Asia reflect broad changes in the monsoon, as opposed to local meteoric precipitation. The EASM records from Sanbao largely follow orbital-scale insolation changes, yet exhibit similar variability to Greenland ice core δ18O on millennial to centennial scales during the early to middle Holocene (&#x03B3l = 0.94). [ABSTRACT FROM AUTHOR]

A 700-year semi-quantitative history of diffuse groundwater recharge in the Badain Jaran Desert (Inner Mongolia) is proposed on the basis of solute data from multiple unsaturated zone groundwater profiles using mass balance of chloride to establish recharge rates and profile chronologies. Four relatively humid (1330-1430, 1500-1620, 1700-1780 and 1950-1990) and three relatively arid phases (1430-1500, 1620-1700 and 1900-1950) are discernable across the profiles. The recharge history broadly reflects multidecadal to centurial timescale precipitation changes in the northern Tibetan Plateau and suggests that variations in East Asian Summer Monsoon intensity affect desert recharge rates. Uncertainties in the records owing to assumptions about the Cl inputs are examined by comparing deterministic and stochastic Cl input scenarios. Such records are valuable for assessing spatial aspects of climate changes in the region, as well as for informing sustainable water resource management strategies for northwestern China's drylands. [ABSTRACT FROM AUTHOR]

A compilation of early-Holocene terrestrial records from lacustrine sediments, ice cores, peat bog, palaeosols, stalagmites and flood sediments from China indicates that the early-Holocene climate was unstable and characterized by at least one centennial-scale (500-200 years) cooling event between 9.0 and 7.6 ka BP. The cold period recorded in different settings has been previously linked to the 8.2 ka event suggested by δ18Oice from Greenland ice cores, but the differences in time duration and regional climate conditions have been attributed to monsoon systems, inadequate age control and sampling resolution, and complex topography in China. However, our compilation indicates that it is premature to attribute the cold periods recorded at different locations in China simply to the 8.2 ka event, let alone to attribute the cause of those anomalies to a freshening of the North Atlantic Ocean circulation. Whether there was one synchronous event or not in China, where the climate is mainly affected by the monsoons and the westerlies, is open to discussion, because most of the records lack sufficient dating control to define clearly the nature of the cooling event. If a cooling event did occur, more evidence is required in multiple dimensions to characterize the time duration, magnitude and cause of the event, so much work remains to be done. [ABSTRACT FROM AUTHOR]

A palaeohydrological reconstruction on decadal scale for the period 15 000–2000 cal. yr BP based on calculated net accumulation rates for biogenic silica (F-bSiO2) and additional proxies (sedimentological data, geochemical sediment characteristics and pollen) is derived from varved sediments of Lake Sihailongwan (SHL). In Lake SHL, F-bSiO2 is positively correlated with the inflow of nutrient-rich groundwater. Since groundwater inflow is mainly fed by seepage of summer monsoon rainfall, F-bSiO2 documents changes in summer monsoon strength. Summer monsoon rainfall was enhanced in the early Holocene around 9800 and 7800 cal. yr BP. Groundwater inflow during these periods did not reach the high level of the Lateglacial warm period (c. 14 300–12 500 cal. yr BP) when the vicinity of the lake was less densely covered with woody vegetation than in the Holocene. Aeolian influx of silt-sized debris was relatively higher during an overall drier period between 9500 and 8000 cal. yr BP. A mid-Holocene sedimentation interval with distinct century-scale variability in summer monsoon rainfall documents a positive correlation between rainfall and siliciclastic influx that reflects a more efficient removal of mineral aerosols for increased rainfall at an overall high dust concentration over the Asian continent. Summer monsoon rainfall reached minima around 6400, 4900, 3700 and 2200 cal. yr BP. Remarkably, aeolian siliciclastic influx peaked at the beginning and at the end of a dry interval between 4100 and 3600 cal. yr BP. Around 3600 cal. yr BP Lake SHL received substantial aeolian influx of different geochemical provenance. [ABSTRACT FROM AUTHOR]

This study employs a multiproxy approach in the reconstruction of Holocene monsoon history from sedimentary sequences obtained from the Pearl River Estuary, southern China. A set of modern surface sediment samples were collected within and outside the estuary, and a sediment core was obtained from the mouth of the estuary. A range of modern environmental variables were recorded including water salinity (summer, winter and annual average) and water depth. The diatom results show a good relationship with water salinity, with marine diatoms dominating the more distal samples from outside the main estuary and freshwater diatoms dominating the proximal samples influenced by higher freshwater flux. This pattern is matched by the bulk organic carbon isotopes. The isotope values vary between -21.1±0.3‰ for samples from the fully marine environment, between -23.2±0.8‰ and -23.7±0.8‰ for samples from the mid to outer estuary brackish water environment and less than -24.7±1.3‰ for samples from the inner estuary close to the freshwater sources. Similarly, the C/N ratios vary from below 7±0.6 in the marine end-members to over 14.8±3.0 in the freshwater end-members. Both the diatom and carbon data from the sediment core reveal a significant increase in freshwater flux from 8500 cal. yr BP resulting from the enhanced summer monsoon regime in early Holocene. The strength of freshwater flux reached its highest between 7500 and 6000 cal. yr BP. In the last 6000 years, freshwater flux decreased towards present, reflecting a gradual weakening of the summer monsoon. [ABSTRACT FROM AUTHOR]

Middle- to late-Holocene palaeoclimate change has been reconstructed at high resolution by the analysis of the carbon and oxygen isotopes from a thermal ionization mass spectrometric (TIMS) U / Th dated stalagmite from Xiangshui Cave, near Guilin, Guangxi Province, China. The carbon and oxygen isotopic records from the stalagmite suggest that changes in the Asian monsoon since the middle Holocene (6000 BP) can be divided into two periods: (1) an interval from 6000 to 3800 BP when a strong East Asian summer monsoon gradually weakened and climate was relatively warm and humid; (2) a cool period from 3800 to 373 BP when the East Asian summer monsoon was relatively weak and the winter monsoon was probably relatively strong. This cooler interval was interspersed with a number of short warm periods. This interpretation is largely based upon the general increase in δ18O values of the stalagmite between 6000 and 3800 BP and shifts in δ18O about a relatively heavy mean value between 3800 and 373 BP. The 6000 to 3800 BP trend is probably associated with decrease in precipitation and temperature subsequent to the mid-Holocene climatic optimum. [ABSTRACT FROM AUTHOR]