Asian winter monsoon controls marine primary productivity in north Arabian Sea during the Holocene

Abstract

The Arabian Sea (AS), which is strongly impacted by monsoon winds, is one of the most biologically productive regions. The forcing of Asian monsoons on Holocene productivity remains debated in north AS, an area influenced by summer and winter monsoon. A sediment core from Makran margin was utilized to analyze organic biomarkers and high-resolution bromine intensities, unveiling the forces of biological productivity through the past 8000 years. Alkenone sea surface temperature (SST) records show significant cooling in north AS and augmented SST difference between north and west AS toward the late Holocene, suggesting Asian winter monsoon (AWM) strengthening during the period. The Holocene productivity signals in north AS, indicated by the bromine to rubidium ratio and multiple biomarkers, are responsive to SST changes and thus mainly controlled by the AWM variation, not modulated by Asian summer monsoon (ASM). Millennial-to-centennial-scale variability of marine productivity during the Holocene is closely related to North Atlantic climate oscillations, mainly through atmospheric circulations in winter.