Abrupt upwelling and CO2 outgassing episodes in the north-eastern Arabian Sea since mid-Holocene

Autor: Syed Azharuddin, Pawan Govil, Thomas B. Chalk, Mayank Shekhar, Gavin L. Foster, Ravi Mishra
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Scientific Reports, Vol 12, Iss 1, Pp 1-12 (2022)
Druh dokumentu: article
ISSN: 2045-2322
28483839
DOI: 10.1038/s41598-022-07774-4
Popis: Abstract Identifying the causes and consequences of natural variations in ocean acidification and atmospheric CO2 due to complex earth processes has been a major challenge for climate scientists in the past few decades. Recent developments in the boron isotope (δ11B) based seawater pH and pCO2 (or pCO2 sw) proxy have been pivotal in understanding the various oceanic processes involved in air-sea CO2 exchange. Here we present the first foraminifera-based δ11B record from the north-eastern Arabian Sea (NEAS) covering the mid-late Holocene (~ 8–1 ka). Our record suggests that the region was overall a moderate to strong CO2 sink during the last 7.7 kyr. The region behaved as a significant CO2 source during two short intervals around 5.5–4 ka and 2.8–2.5 ka. The decreased pH and increased CO2 outgassing during those abrupt episodes are associated with the increased upwelling in the area. The upwelled waters may have increased the nutrient content of the surface water through either increased supply or weaker export production. This new dataset from the coastal NEAS suggests that, as a potential result of changes in the strength of the El-Nino Southern Oscillation, the region experienced short episodes of high CO2 outgassing and pre-industrial ocean acidification comparable to or even greater than that experienced during the last ~ 200 years.
Databáze: Directory of Open Access Journals
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