The upmost segment (Holocene series) of the Milanggouwan stratigraphic section (MGS1) in the Salawusu River valley shows 11 sedimentary cycles of dune sands and fluvio-lacustrine facies, or dune sands and paleosols. T...The upmost segment (Holocene series) of the Milanggouwan stratigraphic section (MGS1) in the Salawusu River valley shows 11 sedimentary cycles of dune sands and fluvio-lacustrine facies, or dune sands and paleosols. The analysis of the magnetic susceptibility of this segment suggests that there are 11 magnetic susceptibility cycles with the value alternating from low to high, in which the layers of the dune sands correspond to the lower value of the magnetic susceptibility and the layers of fluvio-lacustrine facies and paleosols correspond to the higher peaks. The study reveals that the low and high magnetic susceptibility values indicate the climate dominated by cold-arid winter monsoon and warm-humid summer monsoon of East Asia, respectively, and the study area has experienced at least 22 times of millennial-centennial scales climate alternation from the cold-arid to the warm-humid during the Holocene. In terms of the time and the climate nature, the variations basically correspond to those of the North Atlantic and some records of cold-warm changes in China as well. They might be caused by the alternation of winter and summer monsoons in the Mu Us Desert induced by global climate fluctuations in the Holocene.展开更多
Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes...Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not clear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.展开更多
Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on t...Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on the relationship be tween millennial-scale lake C sequestration,hydrological status and vegetation,which has important scientific signifi cance in improving our understanding of lake C stocks and storage mechanisms.Here,we present a comprehensive study of pollen records,organic geochemical proxies,lake-level records,sediment accumulation rate(SAR)and organic C accu mulation rate(CAR)in China since the Holocene.We also include numerical climate classification and lake-level simula tions,to investigate variations of lake C sequestration,hydrological status and vegetation during the Holocene.Results in dicate that the evolution of lake C accumulation showed an out-of-phase relationship with hydrological status and vegeta tion in China.Lake C accumulation exhibited an overall trend of increasing from the early to late Holocene in response to gradually increasing terrestrial organic matter input.However,China as a whole experienced the densest vegetation cover in the middle Holocene,corresponding to the mid-Holocene optimum of a milder and wetter climate.Optimal hydrologi cal conditions were asynchronous in China;for example,early Holocene in Asian monsoon dominated areas,and middle Holocene in westerlies controlled regions.Our synthesis indicated that climate change was the main factor controlling the long-term variability in lake C accumulation,hydrologic conditions,as well as vegetation,and human influences were usu ally superimposed on the natural trends.展开更多
全新世(11.7 ka BP)作为最年轻的地质年代,其气候变化相对晚更新世冰期稳定,但仍存在千百年尺度的气候波动。造成这些气候波动的可能有多种原因,但至今还没有统一的认识。这一时期的气候变化与人类发展有密切的关系,因此其短尺度的气候...全新世(11.7 ka BP)作为最年轻的地质年代,其气候变化相对晚更新世冰期稳定,但仍存在千百年尺度的气候波动。造成这些气候波动的可能有多种原因,但至今还没有统一的认识。这一时期的气候变化与人类发展有密切的关系,因此其短尺度的气候变化越来越受到学界的关注,已经开展了大量的研究。通过对文献资料分析,综述了全新世千百年尺度的气候突变的原因。全新世早期温度普遍升高主要与太阳活动变化有关,期间冰盖消融与海洋环流作用引起百年尺度的气候事件。全新世中期气温最高,但也发现多次干冷气候事件,主要为冰川活动导致。全新世晚期温度降低,主要是以火山活动导致的气候变冷。其他因素如地球轨道参数、潮汐作用、冰川作用、海洋环流等在全新世各个时期对气候造成影响。展开更多
Studies on a high resolution loess section in Huining County reveal that the behavior of climate shows high instability during the last glaciation. Results reflect that climate in Loess Plateau oscillates on millennia...Studies on a high resolution loess section in Huining County reveal that the behavior of climate shows high instability during the last glaciation. Results reflect that climate in Loess Plateau oscillates on millennial time scales during the last glacial period. These can be teleconnected with the records of Dansgaard-Oeschger cycles and Heinrich events in high latitudes. Results also demonstrate that variations in the intensity of wind regime on the Loess Plateau have a close correlation with the changes of global ice sheets volume. All these suggest that two-level fordngs may drive climate changes in central Asia. The first level is the volume changes of ice sheets and the second level with short time scales is superimposed upon the first level on a nearly global scale.展开更多
中国黄土高原的黄土-古土壤风尘堆积序列具有粒度细、沉积速率高和连续性好等特征,是古气候学研究的重要组成部分。黄土沉积物在轨道尺度上与全球气候关系密切,可以记录千年-百年尺度的快速气候事件。中国黄土古气候学取得的核心成果之...中国黄土高原的黄土-古土壤风尘堆积序列具有粒度细、沉积速率高和连续性好等特征,是古气候学研究的重要组成部分。黄土沉积物在轨道尺度上与全球气候关系密切,可以记录千年-百年尺度的快速气候事件。中国黄土古气候学取得的核心成果之一,就是磁化率可以作为东亚夏季风替代性指标,然而,磁化率在古气候研究中存在多解性,导致其在高分辨率研究中应用较少。文中选择黄土高原的赵家川和巴谢剖面磁化率数据,通过与格陵兰冰心和中国石笋等高分辨率古气候记录进行对比,发现赵家川剖面磁化率记录了4次Heinrich事件,巴谢剖面磁化率记录了全新世以来新仙女木、9.2 ka和4.2 ka 3次气候快速恶化事件。通过对比分析巴谢剖面磁化率记录的3次快速气候事件及其可能的驱动因素,认为太阳辐射减弱可能是主要因素。展开更多
A ca. 4000a decadal-resolution climate proxy record of the mean grain-size from a lake (or mash) sediment at the southern margin of the Tarim Basin, correlates visu- ally with the atmospheric △14C, record from tree r...A ca. 4000a decadal-resolution climate proxy record of the mean grain-size from a lake (or mash) sediment at the southern margin of the Tarim Basin, correlates visu- ally with the atmospheric △14C, record from tree ring (residual △14C, solar proxy)and the GISP2 ice core 8O record (tem- peralure proxy). In general, △14 C maxima (solar minima) are coincident With cold (wet) periods in the study area and cold periods in the (;reenland ice core. Power spectrum analysis revealed statislically significant periodicities of 196a, 121a, 97a, 62a, 45a and 33—30a, which are similar to those prin- cipal solar-oscillation periods as inferred from the atmos- pheric radiocarbon and other proxy records. Possible solar forcing is addressed to be the main driving forcing of climate change in the southern margin of Tarim Basin.展开更多
基金Under the auspices of National Basic Research Program of China (No. 2010CB833405)National Natural Science Foundation of China (No. 40772118, 49971009)
文摘The upmost segment (Holocene series) of the Milanggouwan stratigraphic section (MGS1) in the Salawusu River valley shows 11 sedimentary cycles of dune sands and fluvio-lacustrine facies, or dune sands and paleosols. The analysis of the magnetic susceptibility of this segment suggests that there are 11 magnetic susceptibility cycles with the value alternating from low to high, in which the layers of the dune sands correspond to the lower value of the magnetic susceptibility and the layers of fluvio-lacustrine facies and paleosols correspond to the higher peaks. The study reveals that the low and high magnetic susceptibility values indicate the climate dominated by cold-arid winter monsoon and warm-humid summer monsoon of East Asia, respectively, and the study area has experienced at least 22 times of millennial-centennial scales climate alternation from the cold-arid to the warm-humid during the Holocene. In terms of the time and the climate nature, the variations basically correspond to those of the North Atlantic and some records of cold-warm changes in China as well. They might be caused by the alternation of winter and summer monsoons in the Mu Us Desert induced by global climate fluctuations in the Holocene.
基金supported by the National Natural Science Foundation of China (Grant No. 41371009)the Fundamental Research Fund for the Central Universities of China (Grant No. lzujbky2013-127)
文摘Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not clear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes aremainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41822708 and 41571178)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA20100102)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. lzujbky-2018-k15)the Second Tibetan Plateau Scientific Expedition (STEP) program (Grant No. XDA20060700)
文摘Lakes have received considerable attention as long-term sinks for organic carbon(C)at regional and global scales.Previ ous studies have focused on assessment and quantification of carbon sinks,and few have worked on the relationship be tween millennial-scale lake C sequestration,hydrological status and vegetation,which has important scientific signifi cance in improving our understanding of lake C stocks and storage mechanisms.Here,we present a comprehensive study of pollen records,organic geochemical proxies,lake-level records,sediment accumulation rate(SAR)and organic C accu mulation rate(CAR)in China since the Holocene.We also include numerical climate classification and lake-level simula tions,to investigate variations of lake C sequestration,hydrological status and vegetation during the Holocene.Results in dicate that the evolution of lake C accumulation showed an out-of-phase relationship with hydrological status and vegeta tion in China.Lake C accumulation exhibited an overall trend of increasing from the early to late Holocene in response to gradually increasing terrestrial organic matter input.However,China as a whole experienced the densest vegetation cover in the middle Holocene,corresponding to the mid-Holocene optimum of a milder and wetter climate.Optimal hydrologi cal conditions were asynchronous in China;for example,early Holocene in Asian monsoon dominated areas,and middle Holocene in westerlies controlled regions.Our synthesis indicated that climate change was the main factor controlling the long-term variability in lake C accumulation,hydrologic conditions,as well as vegetation,and human influences were usu ally superimposed on the natural trends.
文摘全新世(11.7 ka BP)作为最年轻的地质年代,其气候变化相对晚更新世冰期稳定,但仍存在千百年尺度的气候波动。造成这些气候波动的可能有多种原因,但至今还没有统一的认识。这一时期的气候变化与人类发展有密切的关系,因此其短尺度的气候变化越来越受到学界的关注,已经开展了大量的研究。通过对文献资料分析,综述了全新世千百年尺度的气候突变的原因。全新世早期温度普遍升高主要与太阳活动变化有关,期间冰盖消融与海洋环流作用引起百年尺度的气候事件。全新世中期气温最高,但也发现多次干冷气候事件,主要为冰川活动导致。全新世晚期温度降低,主要是以火山活动导致的气候变冷。其他因素如地球轨道参数、潮汐作用、冰川作用、海洋环流等在全新世各个时期对气候造成影响。
基金Project supported by the National Natural Science Foundation of China.
文摘Studies on a high resolution loess section in Huining County reveal that the behavior of climate shows high instability during the last glaciation. Results reflect that climate in Loess Plateau oscillates on millennial time scales during the last glacial period. These can be teleconnected with the records of Dansgaard-Oeschger cycles and Heinrich events in high latitudes. Results also demonstrate that variations in the intensity of wind regime on the Loess Plateau have a close correlation with the changes of global ice sheets volume. All these suggest that two-level fordngs may drive climate changes in central Asia. The first level is the volume changes of ice sheets and the second level with short time scales is superimposed upon the first level on a nearly global scale.
文摘中国黄土高原的黄土-古土壤风尘堆积序列具有粒度细、沉积速率高和连续性好等特征,是古气候学研究的重要组成部分。黄土沉积物在轨道尺度上与全球气候关系密切,可以记录千年-百年尺度的快速气候事件。中国黄土古气候学取得的核心成果之一,就是磁化率可以作为东亚夏季风替代性指标,然而,磁化率在古气候研究中存在多解性,导致其在高分辨率研究中应用较少。文中选择黄土高原的赵家川和巴谢剖面磁化率数据,通过与格陵兰冰心和中国石笋等高分辨率古气候记录进行对比,发现赵家川剖面磁化率记录了4次Heinrich事件,巴谢剖面磁化率记录了全新世以来新仙女木、9.2 ka和4.2 ka 3次气候快速恶化事件。通过对比分析巴谢剖面磁化率记录的3次快速气候事件及其可能的驱动因素,认为太阳辐射减弱可能是主要因素。
文摘A ca. 4000a decadal-resolution climate proxy record of the mean grain-size from a lake (or mash) sediment at the southern margin of the Tarim Basin, correlates visu- ally with the atmospheric △14C, record from tree ring (residual △14C, solar proxy)and the GISP2 ice core 8O record (tem- peralure proxy). In general, △14 C maxima (solar minima) are coincident With cold (wet) periods in the study area and cold periods in the (;reenland ice core. Power spectrum analysis revealed statislically significant periodicities of 196a, 121a, 97a, 62a, 45a and 33—30a, which are similar to those prin- cipal solar-oscillation periods as inferred from the atmos- pheric radiocarbon and other proxy records. Possible solar forcing is addressed to be the main driving forcing of climate change in the southern margin of Tarim Basin.
