TY - JOUR A1 - Dallmeyer, Anne A1 - Claussen, Martin A1 - Ni, Jian A1 - Cao, Xianyong A1 - Wang, Yongbo A1 - Fischer, Nils A1 - Pfeiffer, Madlene A1 - Jin, Liya A1 - Khon, Vyacheslav A1 - Wagner, Sebastian A1 - Haberkorn, Kerstin A1 - Herzschuh, Ulrike T1 - Biome changes in Asia since the mid-Holocene BT - an analysis of different transient Earth system model simulations JF - Climate of the past : an interactive open access journal of the European Geosciences Union N2 - The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene. Y1 - 2017 U6 - https://doi.org/10.5194/cp-13-107-2017 SN - 1814-9324 SN - 1814-9332 VL - 13 IS - 2 SP - 107 EP - 134 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Dallmeyer, Anne A1 - Claussen, Martin A1 - Ni, Jian A1 - Cao, Xianyong A1 - Wang, Yongbo A1 - Fischer, Nils A1 - Pfeiffer, Madlene A1 - Jin, Liya A1 - Khon, Vyacheslav A1 - Wagner, Sebastian A1 - Haberkorn, Kerstin A1 - Herzschuh, Ulrike T1 - Biome changes in Asia since the mid-Holocene BT - An analysis of different transient Earth system model simulations T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - The large variety of atmospheric circulation systems affecting the eastern Asian climate is reflected by the complex Asian vegetation distribution. Particularly in the transition zones of these circulation systems, vegetation is supposed to be very sensitive to climate change. Since proxy records are scarce, hitherto a mechanistic understanding of the past spatio-temporal climate-vegetation relationship is lacking. To assess the Holocene vegetation change and to obtain an ensemble of potential mid-Holocene biome distributions for eastern Asia, we forced the diagnostic biome model BIOME4 with climate anomalies of different transient Holocene climate simulations performed in coupled atmosphere-ocean(-vegetation) models. The simulated biome changes are compared with pollen-based biome records for different key regions. In all simulations, substantial biome shifts during the last 6000 years are confined to the high northern latitudes and the monsoon-westerly wind transition zone, but the temporal evolution and amplitude of change strongly depend on the climate forcing. Large parts of the southern tundra are replaced by taiga during the mid-Holocene due to a warmer growing season and the boreal treeline in northern Asia is shifted northward by approx. 4 degrees in the ensemble mean, ranging from 1.5 to 6 degrees in the individual simulations, respectively. This simulated treeline shift is in agreement with pollen-based reconstructions from northern Siberia. The desert fraction in the transition zone is reduced by 21% during the mid-Holocene compared to pre-industrial due to enhanced precipitation. The desert-steppe margin is shifted westward by 5 degrees (1-9 degrees in the individual simulations). The forest biomes are expanded north-westward by 2 degrees, ranging from 0 to 4 degrees in the single simulations. These results corroborate pollen-based reconstructions indicating an extended forest area in north-central China during the mid-Holocene. According to the model, the forest-to-non-forest and steppe-to-desert changes in the climate transition zones are spatially not uniform and not linear since the mid-Holocene. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 643 KW - Last Glacial Maximum KW - Eastern Continental Asia KW - summer monsoon precipitation KW - PMIP2 coupled simulations KW - Global Vegetation Model KW - northern high‐latitudes KW - Holocene climate change KW - Tibetan Plateau KW - environmental changes KW - Inner Mongolia Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-418755 SN - 1866-8372 IS - 643 SP - 107 EP - 134 ER - TY - JOUR A1 - Wang, Yongbo A1 - Bekeschus, Benjamin A1 - Handorf, Doerthe A1 - Liu, Xingqi A1 - Dallmeyer, Anne A1 - Herzschuh, Ulrike T1 - Coherent tropical-subtropical Holocene see-saw moisture patterns in the Eastern Hemisphere monsoon systems JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The concept of a Global Monsoon (GM) has been proposed based on modern precipitation observations, but its application over a wide range of temporal scales is still under debate. Here, we present a synthesis of 268 continental paleo-moisture records collected from monsoonal systems in the Eastern Hemisphere, including the East Asian Monsoon (EAsM), the Indian Monsoon (IM), the East African Monsoon (EAfM), and the Australian Monsoon (AuM) covering the last 18,000 years. The overall pattern of late Glacial to Holocene moisture change is consistent with those inferred from ice cores and marine records. With respect to the last 10,000 years (10 ka), i.e. a period that has high spatial coverage, a Fuzzy c-Means clustering analysis of the moisture index records together with "Xie-Beni" index reveals four clusters of our data set. The paleoclimatic meaning of each cluster is interpreted considering the temporal evolution and spatial distribution patterns. The major trend in the tropical AuM, EAfM, and IM regions is a gradual decrease in moisture conditions since the early Holocene. Moisture changes in the EAsM regions show maximum index values between 8 and 6 ka. However, records located in nearby subtropical areas, i.e. in regions not influenced by the intertropical convergence zone, show an opposite trend compared to the tropical monsoon regions (AuM, EAfM and IM), i.e. a gradual increase. Analyses of modern meteorological data reveal the same spatial patterns as in the paleoclimate records such that, in times of overall monsoon strengthening, lower precipitation rates are observed in the nearby subtropical areas. We explain this pattern as the effect of a strong monsoon circulation suppressing air uplift in nearby subtropical areas, and hence hindering precipitation. By analogy to the modern system, this would mean that during the early Holocene strong monsoon period, the intensified ascending airflows within the monsoon domains led to relatively weaker ascending or even descending airflows in the adjacent subtropical regions, resulting in a precipitation deficit compared to the late Holocene. Our conceptual model therefore integrates regionally contrasting moisture changes into the Global Monsoon hypothesis. (C) 2017 Elsevier Ltd. All rights reserved. KW - Global monsoon KW - Holocene KW - Eastern hemisphere KW - Moisture evolution Y1 - 2017 U6 - https://doi.org/10.1016/j.quascirev.2017.06.006 SN - 0277-3791 VL - 169 SP - 231 EP - 242 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Herzschuh, Ulrike A1 - Cao, Xianyong A1 - Laepple, Thomas A1 - Dallmeyer, Anne A1 - Telford, Richard J. A1 - Ni, Jian A1 - Chen, Fahu A1 - Kong, Zhaochen A1 - Liu, Guangxiu A1 - Liu, Kam-Biu A1 - Liu, Xingqi A1 - Stebich, Martina A1 - Tang, Lingyu A1 - Tian, Fang A1 - Wang, Yongbo A1 - Wischnewski, Juliane A1 - Xu, Qinghai A1 - Yan, Shun A1 - Yang, Zhenjing A1 - Yu, Ge A1 - Zhang, Yun A1 - Zhao, Yan A1 - Zheng, Zhuo T1 - Position and orientation of the westerly jet determined Holocene rainfall patterns in China JF - Nature Communications N2 - Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia. Y1 - 2019 U6 - https://doi.org/10.1038/s41467-019-09866-8 SN - 2041-1723 VL - 10 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Tian, Fang A1 - Cao, Xianyong A1 - Dallmeyer, Anne A1 - Ni, Jian A1 - Zhao, Yan A1 - Wang, Yongbo A1 - Herzschuh, Ulrike T1 - Quantitative woody cover reconstructions from eastern continental Asia of the last 22 kyr reveal strong regional peculiarities JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - We present a calibration-set based on modern pollen and satellite-based Advanced Very High Resolution Radiometer (AVHRR) observations of woody cover (including needleleaved, broadleaved and total tree cover) in eastern continental Asia, which shows good performance under cross-validation with the modern analogue technique (all the coefficients of determination between observed and predicted values are greater than 0.65). The calibration-set is used to reconstruct woody cover from a taxonomically harmonized and temporally standardized fossil pollen dataset (including 274 cores) with 500-year resolution over the last 22 kyr. The spatial range of forest has not noticeably changed in eastern continental Asia during the last 22 kyr, although woody cover has, especially at the margin of the eastern Tibetan Plateau and in the forest-steppe transition area of north-central China. Vegetation was sparse during the LGM in the present forested regions, but woody cover increased markedly at the beginning of the Bolling/Allerod period (B/A; ca. 14.5 ka BP) and again at the beginning of the Holocene (ca. 11.5 ka BP), and is related to the enhanced strength of the East Asian Summer Monsoon. Forest flourished in the mid Holocene (ca. 8 ka BP) possibly due to favourable climatic conditions. In contrast, cover was stable in southern China (high cover) and arid central Asia (very low cover) throughout the investigated period. Forest cover increased in the north-eastern part of China during the Holocene. Comparisons of these regional pollen-based results with simulated forest cover from runs of a global climate model (for 9, 6 and 0 ka BP (ECHAM5/JSBACH similar to 1.125 degrees spatial resolution)) reveal many similarities in temporal change. The Holocene woody cover history of eastern continental Asia is different from that of other regions, likely controlled by different climatic variables, i.e. moisture in eastern continental Asia; temperature in northern Eurasia and North America. (C) 2016 Elsevier Ltd. All rights reserved. KW - Pollen KW - AVHRR KW - Modern analogue technique KW - Quantitative reconstruction KW - East Asian summer monsoon Y1 - 2016 U6 - https://doi.org/10.1016/j.quascirev.2016.02.001 SN - 0277-3791 VL - 137 SP - 33 EP - 44 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Dallmeyer, Anne A1 - Claussen, Martin A1 - Wang, Yongbo A1 - Herzschuh, Ulrike T1 - Spatial variability of Holocene changes in the annual precipitation pattern BT - a model-data synthesis for the Asian monsoon region T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - This study provides a detailed analysis of the mid-Holocene to present-day precipitation change in the Asian monsoon region. We compare for the first time results of high resolution climate model simulations with a standardised set of mid-Holocene moisture reconstructions. Changes in the simulated summer monsoon characteristics (onset, withdrawal, length and associated rainfall) and the mechanisms causing the Holocene precipitation changes are investigated. According to the model, most parts of the Indian subcontinent received more precipitation (up to 5 mm/day) at mid-Holocene than at present-day. This is related to a stronger Indian summer monsoon accompanied by an intensified vertically integrated moisture flux convergence. The East Asian monsoon region exhibits local inhomogeneities in the simulated annual precipitation signal. The sign of this signal depends on the balance of decreased pre-monsoon and increased monsoon precipitation at mid-Holocene compared to present-day. Hence, rainfall changes in the East Asian monsoon domain are not solely associated with modifications in the summer monsoon circulation but also depend on changes in the mid-latitudinal westerly wind system that dominates the circulation during the pre-monsoon season. The proxy-based climate reconstructions confirm the regional dissimilarities in the annual precipitation signal and agree well with the model results. Our results highlight the importance of including the pre-monsoon season in climate studies of the Asian monsoon system and point out the complex response of this system to the Holocene insolation forcing. The comparison with a coarse climate model simulation reveals that this complex response can only be resolved in high resolution simulations. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 905 KW - Asian monsoon KW - holocene KW - precipitation KW - climate modelling KW - moisture reconstructions Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-432771 SN - 1866-8372 IS - 905 ER -