Download or read book Late Holocene Environmental Change on the NE Tibetan Plateau written by and published by . This book was released on 2005 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Holocene Climate Change on the North eastern Tibetan Plateau Reconstructed from Aeolian Sediment Sequences written by Georg Stauch and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aquatic Bioindicators of Late Holocene Environmental Change on the South Central Tibetan Plateau written by Paula Gabriela Echeverría Galindo and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Late Quaternary Hydrological Paleoenvironmental and Geomorphological Processes in the Tibetan Plateau and Its Adjacent Areas written by Xiangjun Liu and published by Frontiers Media SA. This book was released on 2022-02-23 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lake Records of Environmental and Climate Change on the Tibetan Plateau written by Zhang Chengjun and published by Frontiers Media SA. This book was released on 2022-11-07 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reconstructing Climate Variability on the Tibetan Plateau written by Juliane Wischnewski and published by . This book was released on 2010 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spatial and temporal temperature and moisture patterns across the Tibetan Plateau are very complex. The onset and magnitude of the Holocene climate optimum in the Asian monsoon realm, in particular, is a subject of considerable debate as this time period is often used as an analogue for recent global warming. In the light of contradictory inferences regarding past climate and environmental change on the Tibetan Plateau, I have attempted to explain mismatches in the timing and magnitude of change. Therefore, I analysed the temporal variation of fossil pollen and diatom spectra and the geochemical record from palaeo-ecological records covering different time scales (late Quaternary and the last 200 years) from two core regions in the NE and SE Tibetan Plateau. For interpretation purposes I combined my data with other available palaeo-ecological data to set up corresponding aquatic and terrestrial proxy data sets of two lake pairs and two sets of sites. I focused on the direct comparison of proxies representing lacustrine response to climate signals (e.g., diatoms, ostracods, geochemical record) and proxies representing changes in the terrestrial environment (i.e., terrestrial pollen), in order to asses whether the lake and its catchments respond at similar times and magnitudes to environmental changes. Therefore, I introduced the established numerical technique procrustes rotation as a new approach in palaeoecology to quantitatively compare raw data of any two sedimentary records of interest in order to assess their degree of concordance. Focusing on the late Quaternary, sediment cores from two lakes (Kuhai Lake 35.3ʻN; 99.2ʻE; 4150 m asl; and Koucha Lake 34.0ʻN; 97.2ʻE; 4540 m asl) on the semi-arid northeastern Tibetan Plateau were analysed to identify post-glacial vegetation and environmental changes, and to investigate the responses of lake ecosystems to such changes. Based on the pollen record, five major vegetation and climate changes could be identified: (1) A shift from alpine desert to alpine steppe indicates a change from cold, dry conditions to warmer and more moist conditions at 14.8 cal. ka BP, (2) alpine steppe with tundra elements points to conditions of higher effective moisture and a stepwise warming climate at 13.6 cal. ka BP, (3) the appearance of high-alpine meadow vegetation indicates a further change towards increased moisture, but with colder temperatures, at 7.0 cal. ka BP, (4) the reoccurrence of alpine steppe with desert elements suggests a return to a significantly colder and drier phase at 6.3 cal. ka BP, and (5) the establishment of alpine steppe-meadow vegetation indicates a change back to relatively moist conditions at 2.2 cal. ka BP. To place the reconstructed climate inferences from the NE Tibetan Plateau into the context of Holocene moisture evolution across the Tibetan Plateau, I applied a five-scale moisture index and average link clustering to all available continuous pollen and non-pollen palaeoclimate records from the Tibetan Plateau, in an attempt to detect coherent regional and temporal patterns of moisture evolution on the Plateau. However, no common temporal or spatial pattern of moisture evolution during the Holocene could be detected, which can be assigned to the complex responses of different proxies to environmental changes in an already very heterogeneous mountain landscape, where minor differences in elevation can result in marked variations in microenvironments. Focusing on the past 200 years, I analysed the sedimentary records (LC6 Lake 29.5ʻN, 94.3ʻE, 4132 m asl; and Wuxu Lake 29.9ʻN, 101.1ʻE, 3705 m asl) from the southeastern Tibetan Plateau. I found that despite presumed significant temperature increases over that period, pollen and diatom records from the SE Tibetan Plateau reveal only very subtle changes throughout their profiles. The compositional species turnover investigated over the last 200 years appears relatively low in comparison to the species reorganisations during the Holocene. The results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem. Forest clearances and reforestation have not caused forest decline in our study area, but a conversion of natural forests to semi-natural secondary forests. The results from the numerical proxy comparison of the two sets of two pairs of Tibetan lakes indicate that the use of different proxies and the work with palaeo-ecological records from different lake types can cause deviant stories of inferred change. Irrespective of the timescale (Holocene or last 200 years) or region (SE or NE Tibetan Plateau) analysed, the agreement in terms of the direction, timing, and magnitude of change between the corresponding terrestrial data sets is generally better than the match between the corresponding lacustrine data sets, suggesting that lacustrine proxies may partly be influenced by in-lake or local catchment processes whereas the terrestrial proxy reflects a more regional climatic signal. The current disaccord on coherent temporal and spatial climate patterns on the Tibetan Plateau can partly be ascribed to the complexity of proxy response and lake systems on the Tibetan Plateau. Therefore, a multi-proxy, multi-site approach is important in order to gain a reliable climate interpretation for the complex mountain landscape of the Tibetan Plateau.

Download or read book Late Glacial to Holocene Climate and Vegetation Changes on the Tibetan Plateau Inferred from Fossil Pollen Records in Lacustrine Sediments written by Yongbo Wang and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The past climate in central Asia, and especially on the Tibetan Plateau (TP), is of great importance for an understanding of global climate processes and for predicting the future climate. As a major influence on the climate in this region, the Asian Summer Monsoon (ASM) and its evolutionary history are of vital importance for accurate predictions. However, neither the evolutionary pattern of the summer monsoon nor the driving mechanisms behind it are yet clearly understood. For this research, I first synthesized previously published Late Glacial to Holocene climatic records from monsoonal central Asia in order to extract the general climate signals and the associated summer monsoon intensities. New climate and vegetation sequences were then established using improved quantitative methods, focusing on fossil pollen records recovered from Tibetan lakes and also incorporating new modern datasets. The pollen-vegetation and vegetation-climate relationships on the TP were also evaluated in order to achieve a better understanding of fossil pollen records. The synthesis of previously published moisture-related palaeoclimate records in monsoonal central Asia revealed generally different temporal patterns for the two monsoonal subsystems, i.e. the Indian Summer Monsoon (ISM) and East Asian Summer Monsoon (EASM). The ISM appears to have experienced maximum wet conditions during the early Holocene, while many records from the area affected by the EASM indicate relatively dry conditions at that time, particularly in north-central China where the maximum moisture levels occurred during the middle Holocene. A detailed consideration of possible driving factors affecting the summer monsoon, including summer solar insolation and sea surface temperatures, revealed that the ISM was primarily driven by variations in northern hemisphere solar insolation, and that the EASM may have been constrained by the ISM resulting in asynchronous patterns of evolution for these two subsystems. This hypothesis is further supported by modern monsoon indices estimated using the NCEP/NCAR Reanalysis data from the last 50 years, which indicate a significant negative correlation between the two summer monsoon subsystems. By analogy with the early Holocene, intensification of the ISM during coming decades could lead to increased aridification elsewhere as a result of the asynchronous nature of the monsoon subsystems, as can already be observed in the meteorological data from the last 15 years. A quantitative climate reconstruction using fossil pollen records was achieved through analysis of sediment core recovered from Lake Donggi Cona (in the north-eastern part of the TP) which has been dated back to the Last Glacial Maximum (LGM). A new data-set of modern pollen collected from large lakes in arid to semi-arid regions of central Asia is also presented herein. The concept of "pollen source area" was introduced to modern climate calibration based on pollen from large lakes, and was applied to the fossil pollen sequence from Lake Donggi Cona. Extremely dry conditions were found to have dominated the LGM, and a subsequent gradually increasing trend in moisture during the Late Glacial period was terminated by an abrupt reversion to a dry phase that lasted for about 1000 years and coincided with the first Heinrich Event of the northern Atlantic region. Subsequent periods corresponding to the warm Bølling-Allerød period and the Younger Dryas cold event were followed by moist conditions during the early Holocene, with annual precipitation of up to about 400 mm. A slightly drier trend after 9 cal ka BP was then followed by a second wet phase during the middle Holocene that lasted until 4.5 cal ka BP. Relatively steady conditions with only slight fluctuations then dominated the late Holocene, resulting in the present climatic conditions. In order to investigate the relationship between vegetation and climate, temporal variations in the possible driving factors for vegetation change on the northern TP were examined using a high resolution late Holocene pollen record from Lake Kusai. Moving-window Redundancy Analyses (RDAs) were used to evaluate the correlations between pollen assemblages and individual sedimentary proxies. These analyses have revealed frequent fluctuations in the relative abundances of alpine steppe and alpine desert components, and in particular a decrease in the total vegetation cover at around 1500 cal a BP. The climate was found to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, after the 1500 cal a BP threshold in vegetation cover was crossed the vegetation appears to have been affected more by extreme events such as dust storms or fluvial erosion than by the general climatic trends. In addition, pollen spectra over the last 600 years have been revealed by Procrustes analysis to be significantly different from those recovered from older samples, which is attributed to an increased human impact that resulted in unprecedented changes to the composition of the vegetation. Theoretical models that have been developed and widely applied to the European area (i.e. the Extended R-Value (ERV) model and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model) have been applied to the high alpine TP ecosystems in order to investigate the pollen-vegetation relationships, as well as for quantitative reconstructions of vegetation abundance. The modern pollen-vegetation relationships for four common pollen species on the TP have been investigated using Poaceae as the reference taxa. The ERV Submodel 2 yielded relatively high PPEs for the steppe and desert taxa (Artemisia Chenopodiaceae), and low PPEs for the Cyperaceae that are characteristic of the alpine Kobresia meadows. The plant abundances on the central and north-eastern TP were quantified by applying these PPEs to four post-Late Glacial fossil pollen sequences. The reconstructed vegetation assemblages for the four pollen sequences always yielded smaller compositional species turnovers than suggested by the pollen spectra, indicating that the strength of the previously-reported vegetation changes may therefore have been overestimated. In summary, the key findings of this thesis are that (a) the two ASM subsystems show asynchronous patterns during both the Holocene and modern time periods, (b) fossil pollen records from large lakes reflect regional signals for which the pollen source areas need to be taken into account, (c) climate is not always the main driver for vegetation change, and (d) previously reported vegetation changes on the TP may have been overestimated because they ignored inter-species variations in pollen productivity

Download or read book The Mediterranean Sea written by Stefano Goffredo and published by Springer Science & Business Media. This book was released on 2013-09-09 with total page 673 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is an indispensable addition to the multidisciplinary coverage of the science of the Mediterranean Sea. The editors have gathered leading authorities from the fields of Marine Biology, Ecology, paleoclimatology, Chemical and Physical Oceanography, Zoology, Botany, Aquatic Photosynthesis, Socioeconomics, Mariculture, Mediterranean History and Science of Humanity. Beginning with the birth of the Mediterranean Sea and its myths. From coral to fish, an introduction is given to its major inhabitants of plants and animals past and present. The chapters illustrate how organisms interact as part of the structure and function of the Sea's main ecosystems. The rise of the Mediterranean as the cradle of the Western Civilization leads to a discourse on the status of human interaction with the sea. Accelerating global climate change, water warming, ocean acidification and sea level rise, and analyses of their effects on key organisms, entire ecosystems and human socioeconomics are given. Forecasting and predictions are presented taking into account different future scenarios from the IPCC (International Panel on Climate Change). The volume is richly illustrated in color, with an extensive bibliography. A valuable addition to the limited literature in the field, offering up-to-date broad coverage merging science and humanities.​

Download or read book Holocene Paleo Environmental Reconstruction in Central Tibetan Plateau Inferred from a Lacustrine Sediment Record written by Man-Ching Cheung and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Holocene Paleo-environmental Reconstruction in Central Tibetan Plateau Inferred From a Lacustrine Sediment Record" by Man-ching, Cheung, 張敏青, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Previous studies on reconstructing the paleoclimate on the Tibetan Plateauare commonly based on a single proxy, and have thus limited the usage of their results. Therefore this study was designed firstly to evaluate the applicability of organic carbon isotopes from modern plants in the Tibetan Plateau as a paleo-environmental proxy, and secondly to apply palynology, organic geochemistry and biomarkers to the reconstructions ofpaleo-environmental history of central Tibet. The new, comprehensive records reveal the history of regional precipitation, temperature and vegetation change in responding to Holocene climatic changesin the region. Organic carbon isotope (δ13C) and lipid n-alkanes were measured from plant samples collected from various altitudes and environments across the study area. The δ13C results indicate the importance of availability of water to C3/C4 herbs distribution in this alpine region. The molecular distributions of trees, shrubs, herbs and submergent macrophytes show distinctive features in a number of indices. These indices are considered to be useful for paleo-environmental reconstructions. A 5.8m-long peat core, which were dated back to 95,000 yr BP was obtained from a river valley at an altitude of 4300 m above sea level. The pollen data from the core reveals a sparse herbaceous vegetation in the catchment area during early Holocene, suggesting non-favourable conditions for vegetation growth. The environment became wetter during the early mid-Holocene around 8100-7000 cal. yr BP, and since then a sedge-dominated wetland habitat was developed. This vegetation changed little until about 1100 cal. yr BP; from which an increase of drought-tolerant herbs was indicated by the pollen data, implying a slightly drier condition of the latter part of late Holocene. The pollen record suggests that the optimum precipitation in central Tibet occurred later and lasted longer than that in the East Asian Monsoon region. Finally, bulk sample carbon geochemistry(TOC, δ13C) as well as the biomarkers analysis on n-alkanes and GDGTs as paleo-limnology and paleo-temperature indicators respectively were applied to the core. Before 1500 cal. yr BP, the wetland was dominated by both vascular herbs as suggested by the δ13Cdata and aquatic floating/submerged macrophytes as indicated by mid-chain n-alkanes. The relative proportion of the two sources of organic matter input varied slightly, and vascular herbs increased in two episodes(5400 -4700 and 2800 -2300 cal. yr BP) indicated by the increase of long-chain n-alkanes (>n-C25). Considering of the soil water content variation by the ratios of iGDGTs to bGDGTs, the change between the two plant communities could to be caused by different lake status. GDGTs paleo-temperature reconstruction indicates a warm period from 6700 to 6000 cal. yr BP, which is believed to be the warmest and highly humid in central Tibetan region. Then the temperature decreased towards the late Holocene, consistent with other paleo climate records across the Plateau region, i.e. largely controlled by change of solar insolation. Along the decreasing trend, a warm episode at about 1200 yr BP that inferred from MAAT was suggested corresponding with the North Hemisphere Medieval Warming. DOI: 10.5353/th_b5270537 Subjects: Paleoecology - Tibet, Plateau of Paleoecology - Holocene

Download or read book Statistical Modelling of Quaternary Science Data written by Darrel Maddy and published by . This book was released on 1995 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Holocene Climate Changes in the Asia Pacific Region written by Liangcheng Tan and published by Frontiers Media SA. This book was released on 2021-03-08 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Encyclopedia of World Climatology written by John E. Oliver and published by Springer Science & Business Media. This book was released on 2008-04-23 with total page 873 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, given the well-publicized impacts of events such as El Niño, there is an unequaled public awareness of how climate affects the quality of life and environment. Such awareness has created an increasing demand for accurate climatological information. This information is now available in one convenient, accessible source, the Encyclopedia of World Climatology. This comprehensive volume covers all the main subfields of climatology, supplies information on climates in major continental areas, and explains the intricacies of climatic processes. The level of presentation will meet the needs of specialists, university students, and educated laypersons. A successor to the 1986 Encyclopedia of Climatology, this compendium provides a clear explanation of current knowledge and research directions in modern climatology. This new encyclopedia emphasizes climatological developments that have evolved over the past twenty years. It offers more than 200 informative articles prepared by 150 experts on numerous subjects, ranging from standard areas of study to the latest research studies. The relationship between climatology and both physical and social science is fully explored, as is the significance of climate for our future well-being. The information is organized for speedy access. Entries are conveniently arranged in alphabetical order, thoroughly indexed, and cross-referenced. Every entry contains useful citations to additional source materials. The Editor John E. Oliver is Professor Emeritus at Indiana State University. He holds a B.Sc. from London University, and a MA and Ph.D from Columbia University. He taught at Columbia University and then at Indiana State where he was formerly Chair of the Geography-Geology Department, and Assoc iate Dean, College of Arts and Sciences. He has written many books and journal articles in Climatology, Applied Climatology and Physical Geography.

Download or read book Late Holocene Environmental Change written by V. N. Panizzo and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mountain Geoecology and Sustainable Development of the Tibetan Plateau written by Du Zheng and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intense uplift of the Tibetan Plateau in Late Cenozoic Era is one of the most important events in geological history of the Earth. The plateau offers an ideal region for studying of lithospheric formation and evolution, probing into the mechanism of crustal movement, and understanding of changes in environments and geo-ecosystems in Asia. Intense uplift ofthe plateau resulted in drastic changes of natural environment and apparent regional differentiation on the plateau proper and neighboring regions. The plateau therefore becomes a sensitive area of climate change in Asian monsoon region, which is closely related to the global change. As a special physical unit, its ecosystems occupy a prominent position in the world. Due to its extremely high elevation and great extent, natural types and characteristics of physical landscapes on the plateau are quite different from those in lowlands at comparable latitudes, and environments are also different from those in high latitudinal zones. Consequently, the Tibetan Plateau has been classified as one of three giant physical regions in China and considered as a unique unit on Earth. Scientific surveys and expeditions to the Tibetan Plateau on large scale began from 1950's. Amongst them, a number of comprehensive scientific expeditions to the Xizang (Tibet) Autonomous Region, Hengduan Mts. areas, Karakorum and Kunlun Mts. regions, as well as the Hoh Xii Mts. areas, have been successively carried out by the Integrated Scientific Expedition to Tibetan Plateau, sponsored by Chinese Academy of Sciences since 1973.

Download or read book Tracking Environmental Change Using Lake Sediments written by William M. Last and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory Instrumentation NIR analysis of sediment samples Uses of NIRS in palaeolimnology Future perspectives Summary References Fly-ash particles. Neil Rose 319 12. Introduction A brief history Methods of extraction and enumeration Temporal distribution Spatial distribution Source apportionment The future Summary Acknowledgements References Part III: Stable Isotope Techniques 13. Application of stable isotope techniques to inorganic and biogenic carbonates. Emi Ito 351 Introduction Nomenclature and systematics of lake-water Mg/Ca and Sr/Ca ratios of lake-water of dissolved inorganic carbon (DIC) Carbonates in lake-sediments Mollusks Ostracodes Charaphytes Isotope analysis Preparation of carbonate samples for isotope analysis Conclusions Summary Acknowledgments References 14. Carbon and oxygen isotope analysis of lake sediment cellulose: methods and applications. Brent B. Wolfe, Thomas W. D. Edwards, Richard J. Elgood & Kristina R. M. Beuning 373 xi Introduction Stable isotope tracers in lake Historical development Methods Key criteria for paleohydrologic reconstruction Applications Future research directions Summary Acknowledgements References Nitrogen isotopes in palaeolimnology. Michael R. Talbot 15. 401 Introduction Nitrogen in lakes: forms and distribution Nitrogen isotopes Nitrogen isotope studies in palaeolimnology: sampling and measurement Some examples Closing remarks Summary Acknowledgments References Glossary, acronyms and abbreviations 441 Index 493 xiii PREFACE The explosive growth of paleolimnology over the past two decades has provided impetus for the publication of this series of monographs detailing the numerous advances and new techniques being applied to the interpretation of lake histories. This is the second volume in the series and deals mainly with physical and geochemical analytical techniques.

Download or read book Climates Landscapes and Civilizations written by Liviu Giosan and published by John Wiley & Sons. This book was released on 2013-05-09 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 198. Climates, Landscapes, and Civilizations brings together a collection of studies on the history of complex interrelationships between humans and their environment by integrating Earth science with archeology and anthropology. At a time when climate change, overpopulation, and scarcity of resources are increasingly affecting our ways of life, the lessons of the past provide multiple reference frames that are valuable for informing our future decisions and action plans. Volume highlights include discussions of multiple connotations of the Anthropocene, landscapes as a link between climate and humans, synoptic approaches to explore large-scale cultural patterns, regional studies for contextualizing cultural complexity, and environmental determinism and social theory. Straddling the fields of Earth sciences, anthropology, and archaeology and presenting research from across several continents, Climates, Landscapes, and Civilizations will appeal to a wide readership among scientists, scholars, and the public at large.

Download or read book Environmental Change in Drylands Past Present Future written by Kathryn Elizabeth Fitzsimmons and published by Frontiers Media SA. This book was released on 2022-09-07 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: