Research Projects

The Southern Ocean (SO) absorbs the most atmospheric CO₂, is influenced by the Antarctic Circumpolar Current (ACC) and other related deep-water currents such as Circumpolar Deep Water (CDW) and Antarctic Bottom Water (AABW). These ocean currents, along with the Westerly winds in the Southern Hemisphere, significantly contribute to the alteration of atmospheric CO₂ levels during glacial-interglacial cycles. The interglacials occurring after the Mid-Brunhes Transition (MBT; ~430 kyr) displayed elevated CO₂ in the atmosphere compared to those preceding that period. However, the reason behind this climatic shift remains under debate. This study aims to assess the reason behind elevated CO₂ in the atmosphere during the interglacial after the MBT and its linkages with global climate by reconstructing SO surface and thermocline characteristics like sea surface temperature (SST) and subsurface (above thermocline) temperature (TT) and their variability over the last 600 kyr followed by its numerical modelling to assess the future scenario in view of global warming trend. The temperature will be reconstructed using Mg/Ca measurements on surface and subsurface dwellers, planktic foraminifera (like Neogloboquadrina pachyderma, Globigerina bulloides and Globoconella inflata). The salinity and sea ice extent will be reconstructed using stable isotope (δ¹⁸O and δ¹³C) measurements on the above-mentioned planktic foraminifera species. Further, to minimise the error in SST calculation, unsaturated alkenone proxy-based SST will also be reconstructed. The reconstructed SST and other parameters will be used to numerically model the changes in the ACC variability and its influence on CO₂ sequestration in the SO, impacting global climate. The numerical model will be calibrated with modern ARGO data and will be used to assess the future scenario.