The Tibetan Plateau is of particular importance for the global hydrological and energy cycles and thus a key area for understanding the climate evolution and its impact on the availability of current and future water resources. To reconstruct climatic changes including precipitation/evaporation ratios, temperature evolution and melt water input as a base for reconstructing past monsoon dynamics, we study the evolution of lake systems based on ostracod and diatom assemblage analysis and ostracod shell chemistry.
The major goals of the project consist of three topics:
The results of these three parts will then be combined to track the variability of atmospheric moisture transport of the individual wind systems (Westerlies, South and East-Asian monsoons and Winter Monsoon) in space and time back to the Last Glacial Maximum
The techniques applied include the paleoenvironmental analysis of fossil ostracod and diatom assemblages from sediment cores and outcrop profiles using present day ecological tolerances, ecological groups, modern analogue techniques and transfer functions. This provides key data about changes in lake level, salinity, habitat structure, biological productivity, eutrophication and oxygen availability, water temperature, and water energy. The results will be integrated with geochemical analysis of ostracod shells (stable oxygen and carbon isotopes and trace elements) for retrieving information on past water chemistry, changes in water sources (precipitation, melt water from snow, ice and frozen ground), precipitation vs. evaporation ratios, temperature, salinity and seasonality.
Lake sites are strategically selected on the southern and northern Tibetan Plateau in order to detect individual monsoonal air mass impact, e.g. Taro Co in the west, Tangra Yumco in the center and Nam Co in the east. An inter-lake synthesis of proxy data reflecting the regional imprint of specific monsoonal air masses will be compared with results based on statistical downscaling for the last 11 ka to ultimately decipher drivers of Holocene monsoon dynamics.