The Indian summer monsoon contributes to the socio-economic wellbeing of almost one-third of the worlds population. A small change in monsoon rainfall has been demonstrated to have devastating impacts on these populations. Past changes in ancient civilizations have also been linked to abrupt drying. Since instrumental records only go back to the 1870s, paleoclimate records are needed to understand the full range of monsoon variability particularly during the current warm period, the Holocene (~10,000 years ago to present). Despite the need of a thorough understanding of past monsoon dynamics, there exist a spatial and temporal heterogeneity within reconstructions from various proxies and archives. This calls for high-resolution, independently dated paleorecords particularly from regions that primarily receive rain from the Indian summer monsoon.
The plains of northwest India are characterised by several lakes, which are well suited for paleoclimate reconstruction. This project aims at reconstruction of high-resolution past monsoon changes, with a particular focus on centennial scale abrupt changes that could have contributed to changes in societies in the past. Lake sediment and shell carbonate chemistry would be used for past rainfall and temperature reconstructions. The oxygen isotopic composition of gastropod and ostracod shells found in lake sediments can be used to infer rainfall changes when in equilibrium with the oxygen isotopes of the lake water in which they calcify, which in turn is dependent on the amount of precipitation and local hydrological balance. Carbon isotopes of organic matter in these lakes would indicate past vegetational changes. The successful candidate would identify a suitable lake archive followed by sampling and processing of sediments for chemical composition using X-Ray Fluorescence and ICP-OES techniques at IIT Delhi. Preliminary results will help identify key intervals, and stable isotopic and elemental analysis will be carried out at UQ.
This project will provide high-resolution records of the Indian monsoon, one of the world’s most important climate phenomenons. Previous studies have revealed that global monsoon responses to climate change (past and present) can be highly heterogenous, with significant differences compared to predicted responses from global climate models. This study will provide much more robust records for northwest India, which in turn can be used to critique and improve climate models, and help to guide our understanding of how the Indian monsoon will change in response to anthropogenic global warming. This project has broad societal impact, as a very large population is dependant on the Indian summer monsoon for agriculture.