Abstract
Uptake of anthropogenic carbon dioxide from the atmosphere by the surface ocean is leading to global ocean acidification, but regional variations in ocean circulation and mixing can dampen or accelerate apparent acidification rates. Here we use a regional ocean model simulation for the years 1980 to 2013 and observational data to investigate how ocean fluctuations impact acidification rates in surface waters of the Gulf of Alaska. We find that large-scale atmospheric forcing influenced local winds and upwelling strength, which in turn affected ocean acidification rate. Specifically, variability in local wind stress curl depressed sea surface height in the subpolar gyre over decade-long intervals, which increased upwelling of nitrate- and dissolved inorganic carbon-rich waters and enhanced apparent ocean acidification rates. We define this sea surface height variability as the Northern Gulf of Alaska Oscillation and suggest that it can cause extreme acidification events that are detrimental to ecosystem health and fisheries.
Highlights
Uptake of anthropogenic carbon dioxide from the atmosphere by the surface ocean is leading to global ocean acidification, but regional variations in ocean circulation and mixing can dampen or accelerate apparent acidification rates
Following previous work[23], a statistical Empirical Orthogonal Function (EOF) decomposition was performed on monthly anomalies for sea surface height (SSH), salinity, temperature, pCO2, Ωarag, and pH in the Gulf of Alaska (Fig. 1) to determine the leading mode of variability in this system
The Northern Gulf of Alaska Oscillation (NGAO) differs from the North Pacific Gyre Oscillation (NPGO) because this new index solely focuses on the northern Gulf of Alaska, whereas the NPGO describes oceanographic patterns of variability across the entire North Pacific
Summary
Uptake of anthropogenic carbon dioxide from the atmosphere by the surface ocean is leading to global ocean acidification, but regional variations in ocean circulation and mixing can dampen or accelerate apparent acidification rates. Variability in local wind stress curl depressed sea surface height in the subpolar gyre over decade-long intervals, which increased upwelling of nitrate- and dissolved inorganic carbon-rich waters and enhanced apparent ocean acidification rates. We define this sea surface height variability as the Northern Gulf of Alaska Oscillation and suggest that it can cause extreme acidification events that are detrimental to ecosystem health and fisheries. Many marine organisms that make shells from CaCO3 (calcifiers) are sensitive to a decrease in Ω well above the thermodynamic threshold of Ω =18 For this reason, ocean acidification negatively affects important socio-economic subsistence and commercial fisheries, in subpolar regions such as the Gulf of Alaska[9,10]. These fluctuations can exacerbate the seasonal periods of stress from ocean acidification and lead to ocean acidification extreme events earlier than if ocean acidification were the only driver
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
