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Publication . Article . Other literature type . 2016

When can ocean acidification impacts be detected from decadal alkalinity measurements?

Brendan R. Carter; Thomas L. Frölicher; John P. Dunne; Keith B. Rodgers; Richard D. Slater; Jorge L. Sarmiento;
Open Access
Published: 01 Apr 2016 Journal: Global Biogeochemical Cycles, volume 30, pages 595-612
Country: France

We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from freshwater cycling can be mostly avoided through salinity normalization of alkalinity. With the salinity-normalized alkalinity, modeled OA impacts are broadly detectable in the surface of the subtropical gyres by 2030. Discrepancies between this finding and the finding of an earlier analysis suggest that these estimates are strongly sensitive to the patterns of calcium carbonate export simulated by the model. OA impacts are detectable later in the subpolar and equatorial regions due to slower responses of alkalinity to OA in these regions and greater seasonal equatorial alkalinity variability. OA impacts are detectable later at depth despite lower variability due to smaller rates of change and consistent measurement uncertainty.

Subjects by Vocabulary

Microsoft Academic Graph classification: Biogeochemical cycle Environmental science Carbon cycle Ocean gyre geography.geographical_feature_category geography Salinity Ocean acidification Alkalinity Ocean current Oceanography Hydrography


Atmospheric Science, General Environmental Science, Environmental Chemistry, Global and Planetary Change, alkalinity, ocean acidification, trend detection, repeat hydrography, carbon cycle, carbonate system

Funded by
SNSF| Anthropogenic carbon and heat uptake by the Southern Ocean
  • Funder: Swiss National Science Foundation (SNSF)
  • Project Code: 142573
  • Funding stream: Careers | Ambizione
Related to Research communities
European Marine Science