Code and data to reproduce the article "Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations" by Marcos Fontela et al. When used, please cite this doi and/or the original work: Marcos Fontela, Antón Velo, Miguel Gilcoto, Fiz F. Pérez. Anthropogenic CO2 and ocean acidification in Argentine Basin Water Masses over almost five decades of observations. 2021. Science of the Total Environment. Volume 779, 20 July 2021, 146570. ABSTRACT The chemical conditions of the Argentine Basin (western South Atlantic Ocean) water masses are evaluated with measurements from eleven hydrographic cruises to detect and quantify climate change anthropogenic and natural stressors in the ocean carbon system. The database covers almost half-century (1972-2019), a time-span where the mean annual atmospheric carbon dioxide concentration (CO2atm) increased from 3257 to 40811 parts per million of volume (ppm). This increase of atmospheric CO2 (834 ppm, the 64% of the total anthropogenic signal in the atmosphere) leads to an increase in anthropogenic carbon (Cant) across all the water column and the consequent ocean acidification: a decrease in excess carbonate that is unequivocal in the upper (South Atlantic Central Water, SACW) and intermediate water masses (Sub Antarctic Mode Water, SAMW and Antarctic Intermediate Water, AAIW). For each additional ppm in CO2atm the water masses SACW, SAMW and AAIW lose excess carbonate at a rate of 0.398±0.04, 0.476±0.056 and 0.232±0.03 μmol·kg-1·ppm-1 respectively. Modal and intermediate water masses in the Argentine Basin are very sensitive to carbon increases due low buffering capacity. The large rate of AAIW acidification is the synergic effect of carbon uptake combined with deoxygenation and increased remineralization of organic matter. If CO2 emissions follows the path of business-as-usual emissions (SSP 5.85), SACW would become undersaturated with respect to aragonite at the end of the century. The undersaturation in AAIW is virtually unavoidable.