Evolution of Indian Summer Monsoon to its current strength (eISM)

The Indian Summer Monsoon (ISM) is a result of coupled solid Earth and atmospheric processes. The ISM is due to anomalous heating of the air mass over central Asia resulting in the formation of a low-pressure system that draws moist air from the surrounding oceans resulting in intense precipitation across Indochina and south Asia, impacting billions of people. The processes responsible for intensity of this low-pressure system over the continent is related to the regional tectonics since the initial collision of India with Asia around 50 Ma (million year ago) during the Cenozoic. How intensity of monsoon climate, especially rainfall, affects continental erosion and consequently exhumation and uplift of Himalaya and Tibet is largely unknown mainly due to poor constrains on Cenozoic evolution of monsoon. Previous attempts to reach consensus on past ISM intensity is hindered by lack of continuous sedimentary sequences and robust proxies. This project, eISM, will address these shortcomings by (a) utilising newly drilled sediment sequences from three sites in the Bay of Bengal and Andaman Sea, one of the core regions of ISM precipitation, through International Ocean Discovery Programme (IODP) expedition 353 and (b) applying tested proxies for salinity (oxygen isotope of seawater and Ba/Ca ratio from planktonic foraminifera) and erosional strength (from bulk elemental ratio) to reconstruct evolution of ISM precipitation. Monsoon records generated in eISM will help correlate with the increasingly well-constrained onshore tectonic history, in order to understand and quantify the impact of climate-modulated processes in controlling tectonic evolution on Earth.

The scientific outcomes of eISM will improve understanding of one of the largest and most influential climatic systems in the world with direct relevance to billions of people in south Asia. Deficient rainfall leads to drought and famine, while excessive rainfall leads to flooding and similarly adverse impacts to society and economies. The Indian Summer Monsoon (ISM) has significant economic, social and environmental repercussions for the agriculture, flora and fauna of South Asia as it provides up to 80% of annual rainfall in India. Improved knowledge of controls on this climatic system will be essential for policy makers looking to manage resources for future drinking-water security and their economic wellbeing, the majority of which are dependent on the ISM for agricultural success. The rapidly growing global community will also benefit from understanding how future changes in ISM intensification could affect their livelihoods, food and water security.

Scientist and researcher working on eISM will benefit immensely with new collaborations and interactions with shipboard and shore based IODP scientists during sampling, data generation and presentation of results. In addition, members of the scientific community will benefit from the collaboration between palaeoceanographers and solid earth geologists, who can use each other's knowledge and expertise to understand how/if the monsoon evolution is linked to tectonic evolution of Asia and how the monsoon could in turn, be controlling the current tectonic uplift through increased continental weathering. The work will directly benefit scientists trying to quantify sediment discharge from erosion of uplifted Himalaya and its impact on CO2 drawdown and climate.