This project aims to reconstruct and (semi)quantify the Holocene climate variability and regional hydrology in the Central Asia along two W-E transects sandwiching the Tibetan Plateau and one N-S transect cutting across the Plateau. We will use a multiarchive, multiproxy approach and additionally focus on selected time slices (e.g. early Holocene warm period, the Medieval Warm Period, the Little ice age etc). Palaeoclimate simulations of differ¬ent duration and on selected time slices will be carried out using the generated data. The combination of proxy data and model simulations will lead to an improved understanding of the physical mechanisms controlling the monsoon dynamics.
Our lake sediment and treering groups are involevd in CADY project 1 and CADY project 3:
CADY Project 1: Reconstructing Holocene monsoon and westerlies variability in Central Asia and surrounding regions using lake sediments.
Principal Investigators: S. Prasad, J. Mingram, B. Plessen, G. Schettler, A. Brauer.
This subproject undertakes modern monitoring, and multiproxy palaeoclimate investigations on lakes and lacustrine sediments from two W-E transects sandwiching the Tibetan plateau. Transfer functions will be developed from analyses of modern samples from the lake and catchment area, and sediment traps will be used to (semi)-quantify the data from Holocene sediment cores. The results will help in reconstructing the spatio-temporal variability in westerlies-monsoon interactions, and their impact on regional hydrology during the Holocene. The project will focus on selected time slices (e.g. early Holocene warm period, the Medieval Warm Period, the Little ice age etc) to understand the regional impact of global climate change.
CADY Project 3: 20th century Westerlies - Monsoon variability in view of the past 1500 years - high resolution studies on multi-parameter records from tree rings.
Principal Investigators: G. Helle, I. Heinrich.
A multi-proxy approach of year ring width, quantitative wood anatomy and stable isotope (δ13C, δ18O) measurements in tree rings will be used to investigate the dynamics of the Asian Summer Monsoon during the past 1500 years. By combining different inter- and intra-annual proxy data from tree rings, low- and high-frequency variations of temperature, precipitation, evapotranspiration and humidity will be reconstructed. The new tree ring records used for these purposes will come from about 1500-year-old juniper trees from the Alai region in Kyrgyzstan as well as from NE China, where varved lake sediment palaeoclimate records (Ashan, Sihailongwan) for comparison are already available. Calibration and verification of the tree ring proxy records will be based on statistical and regression methods. In addition, the relation between the seasonal dynamics of tree growth and isotopic fractionation processes will be monitored and modelled, aiming at assessing the uncertainties of year-ring-based climate reconstructions. Our reconstructions will be compared with data sets from varved lake sediments on an instrumental time scale to achieve seasonally resolved palaeoclimate information for the period under investigation. The comparison with climate models will further enable a better understanding of the physical mechanisms of monsoon dynamics and allow to verify our palaeoclimate reconstructions.