Ocean acidification along the 24.5°N section in the subtropical North Atlantic

• Published in: Geophysical Research Letters
• Main Authors: Fernández-Guallart, E., Fajar, Noelia, Padín, X. A., Vázquez Rodríguez, Marcos, Calvo, Eva María, Ríos, Aida F., Hernández Guerra, Alonso, Pelejero, Carles, Pérez, Fiz F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons 2015
• Subjects: Seawater pH; Decadal variability; PH variability; Western Basin; North Atlantic; Ocean acidification
• Online Access: http://hdl.handle.net/10261/110345; https://doi.org/10.1002/2014GL062971

9 páginas, 4 figuras.-- Proyecto Carbochange Ocean acidification is directly related to increasing atmospheric CO2 levels due to human activities and the active role of the global ocean in absorbing part of this anthropogenic CO2. Here we present an assessment of the pH changes that have occurred along 24.5°N in the subtropical North Atlantic through comparison of pH observations conducted in 1992 and 2011. It reveals an overall decline in pH values in the first 1000 dbar of the water column. The deconvolution of the temporal pH differences into anthropogenic and nonanthropogenic components reveals that natural variability, mostly owed to a decrease in oxygen levels in particular regions of the section, explains the vertical distribution of the larger pH decreases (up to −0.05 pH units), which are found within the permanent thermocline. The detection of long-term trends in dissolved oxygen in the studied region gains importance for future pH projections, as these changes modulate the anthropogenically derived acidification. The anthropogenic forcing explains significant acidification deeper than 1000 dbar in the western basin, within the Deep Western Boundary Current. We acknowledge funding from the Spanish Ministry of Economy and Competitiveness through grants CSD2008-00077 (Circumnavigation Expedition MALASPINA 2010 Project), CTM2009-08849 (ACDC Project), and CTM2012-32017 (MANIFEST Project) and from the Seventh Framework Programme FP7 CARBOCHANGE (grant agreement 264879). E.F. Guallart was funded by CSIC through a JAE-Pre grant. Peer reviewed