The centennial-scale response of the Indian monsoon to Holocene climate change: a high-resolution lacustrine isotope record from Peiku Co, Tibet

Knowledge of the past variations in the Indian summer monsoon (ISM) is essential for understanding the monsoon system as a whole and its relationship to other parts of the climate system. Despite existing instrumental data and proxy evidence for variations in the ISM at sub-decadal to millennial timescales, we still have a poor understanding of how monsoon circulation has controlled long-term moisture over the Asian landmass. While marine and stalagmite proxy records have provided a framework of variations in the ISM, they reveal little about the hydrological conditions within the continental monsoon domain, where the human population is foremost. Even so, these records show decadal- to century-scale climate oscillations in the ISM that are concurrent with N. Atlantic ocean circulation changes, significant perturbations in tropical ocean temperatures and ENSO-like behaviour in the western Pacific warm pool, potentially forced by variations in solar output. But, it is unclear whether the monsoon responds to high-latitude teleconnections, or plays a primary role in initiating and/or amplifying abrupt climate changes from the tropics via ENSO-like mechanisms. Consequently, pre-instrumental palaeoclimate records of the ISM are key to understanding the origin of monsoon variability. I will investigate ISM variability over the past 15,000 cal. years through a high-resolution isotopic and trace element study of ostracods from sediments in Lake Peiku Co, southern Tibet. Peiku Co offers one of the best archives of information of past moisture changes as it lies at the edge of ISM rains and is therefore sensitive to changes in monsoon intensity. This palaeoclimatic record will be used to evaluate changes in the behaviour of the ISM and to investigate the relative importance of different forcing factors and wider climatic teleconnections.