Hydrology of the Indian Monsoon on Millennial Timescales


OCCI Funded Project: 2007


The Indian monsoon affects the livelihood of over 60% of the world’s population. The monsoon is a consequence of the seasonal temperature contrast between the Indian Ocean and the Asian subcontinent. It strongly impacts agricultural, transportation, health and tourism concerns for the region. Natural and human-forced variations in the monsoon are increasingly important societal concerns. In addition to being of regional importance to more than 3 billion people, variations in the Asian monsoon have been called upon to explain phenomena ranging from millennial-scale changes in the tropical hydrological cycle and emissions of greenhouse gases to million-year scale changes in the chemistry of Earth’s oceans.It is therefore perplexing to acknowledge that we do not yet have a detailed understanding of relatively recent (Holocene) monsoon paleohydrology.

In this study, we will perform an integrated data and modeling study designed to begin to reconstruct the paleohydrology of the Indian monsoon in the Bay of Bengal region. By constructing a geochemical time-series (δ18O and Mg/Ca) of planktonic foraminifera in a new and unique sediment core, we will estimate the magnitude of local ocean δ18O variability and infer salinity and runoff variations that occurred in response to seasonal climate variations in the Holocene. These data will provide a rare record for evaluating the monsoon dynamics of an atmospheric general circulation model similar to those used to predict future hydrological cycle changes. This project represents the first collaboration between Assistant Scientist Liviu Giosan and Associate Scientist Karen Bice, which brings together expertise in climate-induced changes in continental margin sedimentation (Giosan) and construction of quantitative proxy climate records and climate modeling (Bice). As importantly, this project, with both laboratory and computer modeling components, represents an important research opportunity for Camilo Ponton, a second-year MIT-WHOI Joint Program student. The project exposes Camilo Ponton to a host of new analytical techniques (X-ray fluorescence, stable isotope and inductively coupled mass spectrometry, and climate modeling), it also represents Liviu Giosan’s first foray into computer climate modeling, and Karen Bice’s first research in sediments younger than 14 million years old.

This project directly addresses the Ocean and Climate Change Institute theme: “How do changes in the hydrological cycle affect climate on decadal to millennial time scales?”