Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations

Fontela, M., Velo, A., Gilcoto, M., & Pérez, F. F. (2021). Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations. Science of The Total Environment, 779, 146570. https://doi.org/10.1016/j.scitotenv.2021.146570

Summary:

This study evaluated chemical data from eleven hydrographic cruises conducted between 1972-2019 in the Argentine Basin, western South Atlantic Ocean. The aim was to quantify natural and human induced stressors in the carbon system. The authors reported an increase of the mean annual atmospheric carbon dioxide concentration (CO₂^atm) from 325 to 408 ppm of volume (ppm) (64%) in a 47 year time-span covered this study. This increase leads to an increase in anthropogenic carbon (C_ant) across all the water column and consequently to ocean acidification (a decrease in excess carbonate), in particular in the upper and intermediate water masses, that in the Argentine Basin region are very sensitive to changes in carbon system. The large rate of intermediate water masses acidification is a combined effect of carbon uptake, deoxygenation, and increased remineralization of organic matter. If CO₂ emissions follow the path of business-as-usual emissions (SSP 5.85), the upper water masses would become undersaturated with respect to carbonate ion concentrations at the end of the century. The undersaturation in the intermediate water masses in the region of the Argentine Basin is virtually unavoidable.

 

Policy relevant message:

The upper water masses in the Argentine Basin region will become undersaturated with respect to carbonate ion concentrations at the end of the century if CO₂ emissions follow the path of business-as-usual emissions. The undersaturation in the intermediate water masses in the region is virtually unavoidable.