Research Projects

The Southern Ocean plays a crucial role in Earth's climatic change during the glacial-interglacial cycles of the Late Quaternary period by exchanging the carbon between the deep sea and the atmosphere. Such exchange of carbon between the deep sea and the atmosphere is proposed to be governed by two main mechanisms, namely, biological and physical processes. The biological mechanism included iron-mediated higher phytoplankton growth (mainly diatoms) during the glacial periods when iron was supplied through dust fluxes and the presence of more sea ice. Consequently, higher diatom growth enabled carbon dioxide (CO2) sequestration to the deep sea and lowered the concentration of CO2 in the atmosphere. The physical mechanism, on the other hand, included the increased sea ice cover and slow ventilation of waters, both prevented the release of deep-sea stored carbon to the atmosphere during the glacial periods. These mechanisms are evident in the glacial-interglacial climate records from the Atlantic and Pacific sectors of the Southern Ocean. However, a third mechanism was recently proposed by the study of glacial-interglacial climate reconstruction in the Indian sector of the Southern Ocean, which suggested that the changes in the meridional temperature gradient affected by Earth’s obliquity (axial tilt) could be the primary cause of lowered carbon dioxide during the glacial period. Such a hypothesis needs to be tested by the understanding of meridional temperature gradient changes in the Indian sector of the Southern Ocean. Recent studies from the Indian sector of the Southern Ocean suggested that sea-surface temperature (SST) changes were concomitant to the summer insolation changes and atmospheric CO2 concentrations. Consequently, the atmospheric CO2 variations may have been responsible for modulating SST changes in the Southern Ocean at glacial-interglacial time period. Thus, it is imperative to test the above noted hypotheses. The proposed project therefore aims to reconstruct the past SSTs, sea ice presence, diatom productivity, and nutrient concentrations in the Indian sector of the Southern Ocean to understand role of the Indian sector of the Southern Ocean in global climate change.