Climatic modulation of surface acidification rates through summertime wind forcing in the Southern Ocean

• Published in: Nature communications 2018-08, Vol.9 (1), p.3240-11, Article 3240
• Main Authors: Xue, Liang, Cai, Wei-Jun, Takahashi, Taro, Gao, Libao, Wanninkhof, Rik, Wei, Meng, Li, Kuiping, Feng, Lin, Yu, Weidong
• Format: Article
• Language: English
• Subjects: 704/47/4113; 704/829/827; Acidification; Aragonite; Atmospheric models; Carbon dioxide; Climate variability; Humanities and Social Sciences; Modulation; multidisciplinary; Ocean acidification; Ocean models; pH effects; Science; Science (multidisciplinary); Surface water
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05443-7

While the effects of the Southern Annular Mode (SAM), a dominant climate variability mode in the Southern Ocean, on ocean acidification have been examined using models, no consensus has been reached. Using observational data from south of Tasmania, we show that during a period with positive SAM trends, surface water pH and aragonite saturation state at 60°–55° S (Antarctic Zone) decrease in austral summer at rates faster than those predicted from atmospheric CO 2 increase alone, whereas an opposite pattern is observed at 50°–45° S (Subantarctic Zone). Together with other processes, the enhanced acidification at 60°–55° S may be attributed to increased westerly winds that bring in more “acidified” waters from the higher latitudes via enhanced meridional Ekman transport and from the subsurface via increased vertical mixing. Our observations support climatic modulation of ocean acidification superimposed on the effect of increasing atmospheric CO 2 . The Southern Annular Mode is a dominant climate variability mode in the Southern Ocean. Using observational data, the authors show a strong climatic modulation of ocean acidification via Southern Annular Mode -related winds.