Desmet, F., Gruber, N., Köhn, E. E., Münnich, M., & Vogt, M. (2022). Tracking the Space-Time Evolution of Ocean Acidification Extremes in the California Current System and Northeast Pacific. Journal of Geophysical Research: Oceans, 127(5), e2021JC018159. https://doi.org/10.1029/2021JC018159
The emission of carbon dioxide by human activities causes ocean acidification (OA), that is, the decrease of the pH and saturation level of seawater with respect to the carbonate mineral aragonite. Episodic events of unusually low pH and aragonite saturation levels punctuate these long-term declines, potentially intensifying stress on marine plankton. Particularly prone to extremes is the California current system off the U.S. West Coast due to its naturally low pH-aragonite waters and its strong variability. The authors identified and characterized extreme events associated with OA in this region, and their drivers. They find extremes to have a broad range of volumes, durations, and strengths, with a quarter of them carrying corrosive conditions for shelled organisms, that is, aragonite saturation levels below 1. The largest and longest-lived events are associated with cyclonic eddies (whirls of approximately 50–100 km in diameter) that trap upwelled low pH-aragonite waters near the coast. Although representing only 3% of the events, they cause most of the total excess of acidity induced by all identified extremes. The vertical extent and duration of extremes with corrosive mean conditions are expected to impact calcifying organisms, such as pteropods.