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The Shiyang River drainage basin is located in the northwest margin of the Asian monsoon region. Previous studies reached different conclusions about Holocene climatic changes in the basin. Some studies suggested the Holocene climatic changes were mainly controlled by the Asian monsoon and that the climate was relatively humid during the early Holocene (11.6--7.1 cal ka BP). Other studies found the mid-Holocene Climatic Optimum (7.0--5.0 cal ka BP), and this climate condition was similar to the Holocene westerly wind pattern in arid Central Asia. The modern climate is affected by the Asian monsoon and westerly wind in the drainage basin, and the Holocene climatic records showed two different Holocene climatic patterns--a westerly wind pattern and monsoonal pattern. However, it remains unclear what caused the two different Holocene climatic patterns to co-exist in the region. The palynological records are the main evidence for the Holocene climatic changes in the basin. This paper focuses on palynological records for different parts of the drainage basin. Among them, QTH02, QTL-03 and Sanjiaocheng records are located in the terminal lake, and the Hongshuihe record is located in the middle reaches of the basin. In the terminal lake, the palynological records of QTH02 and QTL-03 are similar, but the Sanjiaocheng record differs. The difference is mainly affected by the variable pollen assemblages in the different locations of the lake basin. From comparison and synthesis of the four palynological records, we concluded that the millennial-scale Holocene climatic changes were affected by the combined effects of the Asian monsoon and westerly wind in the drainage basin, which show the complicated Holocene climatic pattern in the northwest margin of the Asian monsoon. [ABSTRACT FROM AUTHOR]

A 310-cm-long sediment core, covering the last 10,200 years, was collected from Taro Co on the southwestern Tibetan Plateau and analyzed for pollen, grain size and total inorganic carbon content. The pollen data showed that vegetation changed from alpine steppe to alpine meadow during 10,200-8,900 cal a BP, to alpine steppe dominated by Artemisia during 8,900-7,400 cal a BP, to alpine meadow during 7,400-3,300 cal a BP and to alpine steppe after 3,300 cal a BP. Correspondingly, the pollen, grain size and total inorganic carbon content results revealed climatic change in this area over four stages. The initial stage was from 10,200 to 8,900 cal a BP, during which the climate changed from cold-dry to warm-humid. The second stage (8,900-7,400 cal a BP) was characterized by a warm and dry climate. However, at approximately 7,400 cal a BP, the climate began to become cold and humid, which continued until 3,300 cal a BP. The last stage, from 3,300 cal a BP to present, was characterized as cold and increasingly arid. Climatic events of the early and mid-late Holocene showed that the area was significantly affected by the westerlies. However, the mid-Holocene climate in Taro Co was controlled by the Indian monsoon. The mid-late Holocene depositional environment record of Taro Co was very important to further elaborate the degree of influence by the westerlies or Indian monsoon. [ABSTRACT FROM AUTHOR]

Changes in biodiversity during periods of global warming are of broad public concern. To study the effect of the warming process on the ecosystem, we carried out pollen analyses on samples from seven selected sections at Qingyang, Ningxian, Yangling, Binxian, Baoji, Yanshi, and Lingbao on the Chinese Loess Plateau in order systematically to evaluate changes in plant diversity since the Last Glacial Maximum (LGM). The plant richness indices (Simpson's diversity index and rarefaction analysis) indicated that the plant diversity of each section increased during the process of warming from the LGM to the Holocene Optimum, especially at Baoji and Lingbao. These results are consistent with many long-timescale geological records, which show that warming can increase biodiversity; therefore, the popular viewpoint that warming leads to biodiversity loss or species extinction needs to be re-examined. [ABSTRACT FROM AUTHOR]

To better understand variation of Holocene Chinese mandiblular morphology, a study was conducted on 23 metric traits of Neolithic ( n=54), Bronze-Iron Ages ( n=184) and modern ( n=92) adult male mandibles from northern China. Results indicate that the linear characters of these Chinese mandibles evolved in the past 7000 years. From the Neolithic to Bronze-Iron Ages to present day, the overall size of mandibles decreased. The linear characters of the mandiblular features varied between different time periods. The decrease of thickness and height of the mandibular corpus primarily occurred during the Neolithic to Bronze-Iron Ages. The decrease in main size was during the Bronze-Iron Ages to present day. It is possible that mandibles became thinner before the overall size decreased. Comparisons also indicate that the bottom part of the face may have decreased more greatly in breadth than the upper portion. The decrease in mandible size may be associated with changes in climate and diet, and with changes in the craniums size. [ABSTRACT FROM AUTHOR]

A high-resolution fossil pollen record from the sedimentary cores of Balikun Lake, northwestern China, combined with modern surface pollen data, is used to reconstruct the history of vegetation and climatic change since 16.7 cal. ka BP. Fossil pollen assemblages and lithology indicate that the study area was dominated by desert. The desert had extremely arid climate and lower effective moisture during 16.7--7.9 cal. ka BP, especially from 16.7 to 8.9 cal. ka BP when the lake maybe dried up. During 8.9--7.9 cal. ka BP, the environment gradually recovered in this area. It was then followed by the optimum period from 7.9 to 4.3 cal. Ka BP, when the effective moisture obviously increased. It was characterized by the typical desert-steppe/steppe vegetation and was accompanied with several patch-birch woodlands around the lake. After that, a short but extremely arid climatic event occurred during 4.3--3.8 cal. ka BP, and the vegetation quickly changed from desert-steppe/steppe to desert. It was a relatively optimum period from 3.8 to 0.53 cal. ka BP showing typical desert-steppe/meadow-steppe landscape. Since 0.53 cal. ka BP, the climate has shown signs of deteriorating again. Furthermore, regional comparison shows that the characteristics of climatic and environmental evolution in this area were clearly different from East Asia monsoonal area during the last 16.7 cal. ka BP. It was characterized by the arid climate during the late-glacial and early Holocene, and relatively wet during the mid-late Holocene. [ABSTRACT FROM AUTHOR]

AMS14C dating and analysis of grain size, major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea. Based on the environmentally sensitive grain size, clay mineral and major element assemblages, the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed. These three proxies, mean grain size (>9.71 µm), chemical index of alteration (CIA) and ratio of smectite to kaolinite in particular, show similar fluctuation patterns. Furthermore, 10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene; these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon. The cooling events correlated well with the results of the δ 18 O curves of the Dunde ice core and GISP2, which therefore revealed a regional response to global climate change. Four stages of the East Asia winter monsoon were identified, i.e. 8300-6300 a BP, strong and unstable; 6300-3800 a BP, strong but stable; 3800-1400 a BP, weak and unstable; after 1400 a BP, weak but stable. [ABSTRACT FROM AUTHOR]

Ostrich eggshell beads and fragments collected from SDG site reflect primordial art and a kind of symbolic behavior of modern humans. Based on stratigraphic data and OSL dating, these ostrich eggshell beads are probably in Early Holocene (< 10 ka BP). Two different prehistoric manufacturing pathways are usually used in the manufacture of ostrich eggshell beads in Upper Paleolithic. According to statistic analysis of the characteristics of ostrich eggshell beads, Pathway 1 is identified from these collections. In pathway 1, blanks are drilled prior to being trimmed to rough discs. They exhibit great potential for the study of the origin of primordial art and the development of ancient cultures and provide important data for studying behavioral options adopted by hominids in SDG area. In addition, they bear important implications for the origin of modern humans in East Asia. [ABSTRACT FROM AUTHOR]

Based on modern pollen studies and reliable chronology of nine AMS 14C dates, a detailed history of vegetation and climate changes during the past 8660 cal. a BP was reconstructed by a high-resolution pollen record from Ugii Nuur in central Mongolia. Poaceae-steppe dominated the study area and the climate was mild and semi-humid before 7800 cal. a BP with a noticeable cool and humid interval at 8350-8250 cal. a BP. Xerophytic plant increased and the climate became warm and dry gradually since 7800 cal. a BP. From 6860 to 3170 cal. a BP, semi-desert steppe expanded, suggesting a prolonged warm and dry climate. Between 3170 and 2340 cal. a BP, regional forest steppe expanded whereas semi-desert steppe retreated, indicating the climate became cool and wet gradually and the humidity reached the maximum at the end of this stage. From 2340 to 1600 cal. a BP, a general cool and wet climate prevailed. And the climatic instability increased after 1600 cal. a BR Review of regional published palaeoclimatic records implies that the mid-Holocene dry climate might have prevailed in vast areas from central Mongolia to arid areas of northwest China. Pollen-based climate reconstruction for UGO4 core was well correlated with the result of climate model on Central Asia by Bush. In addition, several abrupt climatic events (cool and wet) were found and some could be broadly compared with the cool events in Atlantic. [ABSTRACT FROM AUTHOR]

Biomarkers have been widely used to reconstruct phytoplankton productivity and community structure changes, and this method has been applied for the first time in the middle Okinawa Trough during the transition from the last deglaciation to the Holocene. The total content of all marine phytoplankton biomarkers, used as a total productivity indicator, reveals higher productivity during the deglaciation. The ratios of the biomarkers are used as community structure indicators which show that, compared with the Holocene, the contribution from haptophytes decreased while the contributions from diatoms and dinoflagellates increased during the deglaciation. The increased productivity during the deglaciation was likely caused by the stronger winter monsoon. Also increased nutrient supply from terrestrial sources contributes to the higher productivity due to lower sea-level, which is consistent with higher terrestrial biomarker (long-chain n-alkanols) content. These changes in the nutrient supply also contributed to the community structure changes in the Okinawa Trough. [ABSTRACT FROM AUTHOR]

A peat core with depths of 297 cm was obtained from the Dajiuhu Basin (31°29'27"N, 109°59'45"E, 1760 m) in Hubei Province, Central China. 10 AMS ages provide a time control and reveal that this core spans the past about 16.0 kaBP (calibrated age) (14C age: 13.3 kaBP). Multi-proxy indexes analysis of geochemistry shows the following character of climate and environmental changes since about 16 kaBP: (1) The climate during the late-glacial period was cold and wet as a whole, but fluctuated continually. 11.4-12.6 cal. kaBP, 12.6-15.2 cal. kaBP and 15.2-16 kaBP were corresponding respectively to the Younger Drays, Bolling-Allerød Warm Period and the Oldest Drays. (2) Inheriting the some climate characteristics of the late-glacial, the climate during the early-Holocene was wet and temperature increased gradually, during which an obvious dry event around 10.6 cal. kaB appeared. (3) The climate during the mid-Holocene was generally warm and wet. During 9.2-7.5 kaBP, temperature increased gradually, precipitation was less comparatively and the 8.2 kaBP cold event which might be representative in the globe was reflected markedly. Then, multi-proxy records were relatively stable during 6.7-4.2 kaBP, which shows the best water and thermal condition in the Holocene Optimum. (4) Around 4.2 kaBP, the climate and environment transform from warm and wet to cool and dry, which may result in the collapse of the Neolithic Culture and midwifery the civilization of Xia Dynasty in this region. After 0.9 kaBP, the climate turned cool and wet. Climate and environmental changes archived in Dajiuhu peat respond to the global changes since the late-glacial period and can be contrasted to the changes recorded in other high-resolution archives from the East Asia Monsoon region, which take on the variety model that the monsoon strengthened abruptly after the late-glacial, was strong during the early Holocene, subsequently declined and became weak after the middle Holocene with dry climate. According to our analysis, the driving mechanism should be the response of solar radiation changes in the East Asia Monsoon region at middle latitudes. [ABSTRACT FROM AUTHOR]

A high-resolution pollen record of the past 13000 a from Huguangyan Maar Lake reveals the vegetation and environment changes in southern China during the Holocene. It shows that (i) pollen percentage of trees and shrubs reached 56% during the early Holocene (11600-7800 cal a BP), of which the pollen percentage of tropical trees reached a maximum at 9500-8000 cal a BP, reflecting a hot and wet environment; (ii) during the mid-Holocene (7800-4200 cal a BP), the pollen percentage of montane coniferous trees and herbs increased, while the percentage of tropical-subtropical trees decreased, indicating lower temperature and humidity; (iii) in the late Holocene spanning from 4200 to 350 cal a BP, the pollen percentage of herbs and montane conifer increased significantly, indicating a marked decrease of temperature and humidity. Our pollen data reveal that the time period 9500-8000 cal a BP in southern China represents a climatic optimum for the Holocene characterized by hot and wet conditions. This is consistent with the Holocene optimum found in lower latitude regions globally. We speculate that strong insolation might cause the northward migration of the ITCZ and subtropical summer monsoon front, which resulted in an early Holocene optimum in the Huguangyan area. The dry tendency and climate fluctuations of the middle and late Holocene could be associated with a decrease in solar insolation and frequent ENSO event. [ABSTRACT FROM AUTHOR]

Multi-proxy data are presented and a discuss is made of paleoclimatic and paleoenvironmental changes during Holocene from a 225-cm-long sediment core from Wulungu Lake, located in westerly area of China. The chronology is constructed from six AMS radiocarbon dates on the bulk organic matter. Analyses of pollen, TOC, TN, δ13Corg, ostracod assemblages and the shell stable isotopes, suggest Holocene climate pattern as follows: temperate and dry (10.0-7.6 cal. ka BP) -warm and wet (7.6-5.3 cal. ka BP) -warm and moist (5.3-3.6 cal. ka BP) -temperate and dry (3.6-2.1 cal. ka BP)-temperate and moist (2.1-1.3 cal. ka BP) -cool and dry (1.3 cal. ka BP-present). With the climatic change, Wulungu Lake experienced two large-scale retreat (5.3-3.6 cal. ka BP and 1.3 cal. ka BP-present) and an obvious transgression (7.6-5.3 cal. ka BP). The records of climatic and environmental evolution of Wulungu Lake were in good accordance with those of adjacent areas. It responded to regional environmental change, global abrupt climate events and followed the westerly climate change mode. [ABSTRACT FROM AUTHOR]

Previous studies have found that wetlands prevailed in western Chinese Loess Plateau and pine pollen could reach up to 80% in Qin'an area of the plateau during middle Holocene. It was then deduced that forest vegetation covered Qin'an area in a warm and wet climate during middle Holocene. The proxies of molecule biomarkers from two Holocene sections, a swamp-alluvial loess section and a typical loess-paleosol section are used to reconstruct regional vegetation history. It is found that the heavy-molecular-weight (HMW) homobogues of the n-alkanes in all samples exhibit a pronounced odd-over-even predominance, maximizing at C31 and the abundance of the nC27-alkanes is the lowest in nC27, nC29, nC31, i.e. C272931, a typical grass n-alkanes model. The results are the same as those of model surface soil samples under grass cover but different from both forest cover and modern pine leaves, which yield preferentially nC29-alkanes peak. It could be inferred that the area was dominated by grass cover but not forest cover during whole Holocene epoch. The study shows that combining both molecule biomarkers and pollen analysis can avoid the disadvantage of pollen analysis in reconstruction of regional vegetation cover. [ABSTRACT FROM AUTHOR]

A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of mean grain size, organic δ13C (δ13Corg), organic carbon content (TOC), C/N, carbonate content, carbonate δ13C (δ13Ccar) and δ18O (δ18Ocar) were conducted for retrieving the Holocene chronosequence of climatic changes based on 15 AMS 14C dates. The record documented four major stages of climate change in the Ordos Plateau: (IV) a cold and dry condition before ~7.65 14C ka BP; (III) a warm and humid stage between ~7.65 and ~5.40 ka BP; (II) a generally drier and cooler climate since ~5.40 ka BP with two humid events occurring from ~4.70 to ~4.60 ka BP and from ~4.20 to ~3.70 ka BP, and (I) a dry climate characterized by complete desiccation of the lake after 3.70 ka BP. Stage Ill can be further divided Into three sub-stages: (IIIa) a warm and humid episode from ~7.65 to ~6.70 ka BP, (IIIb) a warm and relatively dry episode from ~6.70 to ~6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holocene from ~6.20 to ~5.40 ka BP. [ABSTRACT FROM AUTHOR]

As a good indicator of Holocene climate, the fluctuation of alpine timberline is a synthetical result of impacts of many environmental factors during geological and historical periods and modern times. As the dominant tree species of mountainous conifer forests on the northern slope of Tianshan Mountains in Xinjiang, the distribution of Picea schrenkiana and its population size are sensitive to climatic change. The typical natural profile of Huashuwozi and the nearby Xiaoxigou archaeological profile, located in Quanzijie Township, Jimusaer County in Xinjiang, were chosen to analyze and compare the relative high-resolution pollen records, and to measure 14C dating and SEM (scanning electron microscope) microstructure for charcoal fragments contained in Xiaoxigou profile's cultural layers. The results show that in these two profiles, the high percentages of Picea (more than 20% and 35%, respectively) appeared in the stratum of the same period (2000-1300 a BP), which corresponds to the charcoal fragment's age of Picea schrenkiana contained in Xiaoxigou cultural layers. These results convincingly revealed that during the period of 2000-1300 a BP, the timberline for Picea schrenkiana on the northern slope of Tianshan Mountains in Xinjiang declined by about 330m compared with the present. [ABSTRACT FROM AUTHOR]

A high-resolution oxygen-isotope record from a thorium-uranium-dated stalagmite from Shanbao Cave at Shennongjia reflects variations in the amount of monsoon precipitation for the period from 11.5 to 2.1 ka (1 ka = 1000 cal aBP). Between 11.5 and 9.3 ka, a sharp decrease in δ18O indicates a rapid increase in monsoon precipitation. An interval of generally high monsoon precipitation is observed between 9.3 and 4.4 ka. An arid period has prevailed between 4.4 and 2.1 ka. The long-term trend of Shanbao record appears to follow summer insolation at 33°N latitude. An abrupt decrease in monsoon precipitation around 4.3 ka is synchronous with the collapse of Neolithic culture in central China. This abrupt change could have resulted from the amplification of the gradually decreased summer insolation by the positive vegetation-atmosphere-aerosol feedback. The weakened Asian monsoon events were in concert with decreased Greenland temperature during the early Holocene, centered at 8.2, 8.6, 9.3, 10.2 and 11.0 ka. This correlation suggests that changes in low-latitude monsoon are connected with climate change in high-latitude polar region. [ABSTRACT FROM AUTHOR]

High-resolution Sr/Ca ratios of two Porites corals from Leizhou Peninsula were measured using inductively coupled plasma atomic spectrometry (ICP-AES). TIMS U-Th dating reveals that the life-spans of the two corals are 489–500 AD and 539–530 BC, respectively. Monthly sea surface temperatures (SSTs) during these two periods can be reconstructed from their skeletal St/Ca ratios. The results reveal that SSTs during 539–530 BC were roughly the same as those during 1990–2000 AD in this area, indicating a relative warm climate period. However, the period of 489–500 AD was significantly cooler, with annual mean SST, the 10-a average of minimum monthly winter SSTs and the 10-a average of maximum monthly summer SSTs being about 2, 2.9 and 1°C lower than that in the 1990s, respectively. Such climate patterns agree well with the phenological results recorded in the historic documents in other areas of China. [ABSTRACT FROM AUTHOR]

A continuous 7.44 m lake core was successfully drilled at Gun Nuur Lake, northern Mongolia, and analyses on environment magnetic parameters, organic matter content and organic λ13C were conducted in an attempt to retrieve the Holocene chronosequence of climatic changes based on 6 AMS14C dates. We found that the Holocene climate in northern Mongolia has been alternating between cold (or cool)/wet conditions and warm/arid conditions, and also punctuated with a series of abrupt climate shifts. The abrupt climate shifts occurred around 1750, 2800, 4000, 5200, 7200, and 9200 aBP (14C age), being chronologically correlative to those abrupt climatic events recorded in the highlatitude North Atlantic Ocean. The correlation indicates that the climatic changes in northern Mongolia were linked with those in the North Atlantic Ocean probably via the North Atlantic Oscillation-affected westerly winds. The strength and position of westerly winds might have modulated the Siberian-Mongolian high pressure system (winter monsoon), directly influencing the climate in China. [ABSTRACT FROM AUTHOR]