Enhanced CO2 Degassing From the Tropical Indian Ocean During Cold Climatic Events of the Last Glacial Cycle

Tarique, M and Rahaman, W and Lathika, N and Prabhat, P and Thamban, M and Misra, S (2023) Enhanced CO2 Degassing From the Tropical Indian Ocean During Cold Climatic Events of the Last Glacial Cycle. In: Paleoceanography and Paleoclimatology, 38 (12).

PDF Pal_Pal_2023.pdf - Published Version Restricted to Registered users only Download (1MB)

Abstract

Atmospheric CO2 variability on the glacial�interglacial (G�IG) timescale reflects a balance between oceanic and terrestrial processes involving carbon uptake and release. The Southern Ocean CO2 uptake is considered as an important modulator for the G�IG atmospheric CO2 variability, while the role of tropical ocean ventilation remains enigmatic. We present critical evidence for CO2 ventilation from the tropical Indian Ocean through the reconstruction of the Arabian Sea-surface pCO2 for the past �136 ka utilizing boron isotope (δ11B) record of planktic foraminifera, Globigerinoides ruber. Our site in the Arabian Sea presently acts as a significant source of CO2. The reconstructed �pCO2 (�pCO2 = pCO2 Seawater � pCO2 Atmosphere) record shows an enhanced CO2 degassing up to �50 ppm during the major cooling events, such as the Last Glacial Maximum, Younger Dryas, and Heinrich-Stadials. Our investigation based on multiproxy records of sea-surface temperature, salinity, and productivity suggests that the northward invasion and shoaling of southern source CO2-rich water, coupled with stronger upwelling, resulted in CO2 degassing during these cold intervals. This finding is in align with the tropical Atlantic which also demonstrated an enhanced CO2 degassing during the cold intervals; however, most of the upwelled CO2 was consumed as the water moved away from the upwelling sites. Therefore, our finding, when considered alongside tropical Atlantic records, suggests that tropical oceans played a minor role in reducing atmospheric CO2 levels during the cold intervals of the last glacial cycle, supporting the prevailing hypothesis. © 2023. American Geophysical Union. All Rights Reserved.

Item Type:	Journal Article
Publication:	Paleoceanography and Paleoclimatology
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to author
Keywords:	Boron; Degassing; Glacial geology; Isotopes; Oceanography; Surface waters; Tropics, Arabian sea; Atmospheric CO 2; Boron isotopes; CO2 source�sink; Glacial�interglacial; Last glacial cycles; Ocean ph; Source-sink; Tropical Indian ocean; Tropical ocean, Carbon dioxide, boron isotope; carbon budget; cooling; degassing; glacial-interglacial cycle; Heinrich event; Last Glacial; Last Glacial Maximum; ocean; reconstruction; source-sink dynamics; upwelling; ventilation; Younger Dryas, Arabian Sea; Indian Ocean; Indian Ocean (Tropical); Southern Ocean
Department/Centre:	Others
Date Deposited:	29 Feb 2024 05:59
Last Modified:	29 Feb 2024 05:59
URI:	https://eprints.iisc.ac.in/id/eprint/83735

Actions (login required)

View Item