Decoding late Quaternary paleoclimatic signatures from the western Bay of Bengal: A multiproxy approach

Abstract

Investigating climate teleconnections and their feedback mechanisms in the global climate system during the late Quaternary period is indispensable in combating the adversities of climate change due to global warming and achieving reliable climate predictions. Even though the Indian monsoon system is a major component of the global climate and hydrological system that gets severely impacted by other climate variables and natural climate forcings, its responses and linkages with different climate parameters remain poorly understood. The Bay of Bengal (BoB), a prominent sub-basin of the Northern Indian Ocean, receives rainfall mainly from the Indian Summer Monsoon (ISM) and partly from the Northeast Monsoon (NEM). Further, the basin receives a large quantity of fluvial sediment discharges from both the Himalayan and peninsular rivers. Considering the unique geo-environmental settings of the BoB and its teleconnection with global climate forcings, the present study has attempted to address the paleoclimate and paleoceanographic variability and their plausible linkages with the global climate system using a marine sediment core of ∼2.90 m retrieved from the western BoB. The chronology of the core was established using AMS radiocarbon dates, while past climate and oceanographic conditions were reconstructed through a multiproxy approach. The present study demonstrated a plausible dominance of terrestrially derived C₄ plants during 45−15 ka. Further, the study also suggested a conspicuous increase in the in-situ calcareous productivity observed during 25−14 ka and the last 4 ka associated with poor freshwater stratification. Conversely, the strengthened ISM during 12–4 ka resulted in enhanced freshwater inflows and prominent stratification in the western BoB, inhibiting in-situ calcareous productivity. The present study has implications for millennial-scale hydroclimate changes in the BoB and its linkage with the regional and global climate dynamics.