A glimpse of the Quaternary monsoon history from India and adjoining seas

Abstract

The evolution of the monsoon is briefly summarized taking into account previous studies conducted on both terrestrial and marine records recovered from the Indian subcontinent and the adjoining seas. While the initiation of the monsoon is debated, it seems clear that a major intensification of the summer monsoon occurred at ~ 8.2 Ma. A seasonal monsoon circulation with distinct summer and winter monsoon phases was established at ~ 2.8 Ma. In the Late Quaternary, the summer monsoon weakens during glacial periods as compared to interglacial periods. The centennial to sub-centennial scale changes in the monsoon during both glacial and interglacial periods suggest strong links between high latitude processes and the tropical monsoon and its role in modulating northern hemispheric climate. The glacial terminations are marked by weak monsoon activity. The summer monsoon weakened during the Middle Holocene after the Early Holocene optimum. A change in the monsoon intensity though alters the salinity of the seas surrounding India, the quantitative paleosalinity reconstructions still have large associated uncertainties and an effort should be made to lower them.