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Potential Risks of Ocean Iron Fertilization Include Oxygen Depletion

Ocean Iron Fertilization (OIF) has emerged as a contentious geoengineering technique aimed at enhancing the ocean's biological carbon pump to combat climate change. By introducing iron to iron-deficient regions of the ocean, proponents aim to stimulate the growth of phytoplankton, which absorb atmospheric carbon dioxide (CO2) and eventually sequester it in the deep ocean as they die and sink. While this approach holds promise, it is fraught with potential ecological risks that could far outweigh its benefits. Among these risks are ocean acidification.

Ocean Acidification​

Increased phytoplankton activity from OIF can lead to higher organic matter decomposition rates, which releases additional CO2 back into the water column and contributes to ocean acidification. Acidification particularly endangers marine organisms with calcium carbonate shells or skeletons, such as corals, mollusks, and some plankton species, hampering their ability to build and maintain their structures and survive in increasingly acidic conditions.123

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Footnotes​

  1. Smetacek, V., et al. (2012). Deep carbon export from a Southern Ocean iron-fertilized diatom bloom. Nature, 487(7394), 313-319. https://doi.org/10.1038/nature11229 ↩

  2. Doney, S. C., et al. (2009). Ocean acidification: The other CO2 problem. Annual Review of Marine Science, 1(1), 169-192. https://doi.org/10.1146/annurev.marine.010908.163834 ↩

  3. Fabry, V. J., et al. (2008). Impacts of ocean acidification on marine fauna and ecosystem processes. ICES Journal of Marine Science, 65(3), 414-432. https://doi.org/10.1093/icesjms/fsn048 ↩