Another excellent piece on the potential impacts of ocean acidification on ocean ecosystems was published recently in Nature Geoscience, Andy Ridgwell & Daniela N. Schmidt, Past Constraints on the Vulnerability of Marine Calcifiers to Massive Carbon Dioxide Release, 3 Nature Geoscience 196-200 (Feb. 2010) (subscription required). The researchers in the study employed an Earth system model to simulate and compare past and present changes in carbon dioxide levels in the ocean to assess likely future impacts of declining pH levels on marine species.
Key take-aways from the study include the following:
- Although there has been extensive laboratory assessments of the potential impacts of ocean acidification on marine species, impacts on ecosystems in the open ocean may be different given the potential for species to physiologically evolve or adapt through shifts in biogeography;
- By the year 2150, the calcite saturation horizon (below the point at which calcite begins to resolve), could shoal rapidly to about 600 meters. It would take approximately 10,000 years for the saturation horizon to once again approach pre-industrial levels;
- Benthic foraminers live several years, and thus are most likely to be susceptible to acidification impacts. Deep-sea benthic foraminers experienced large rates of extinction during the Palaeocene-Eoocene thermal maximum 55 million years ago, a period characterized by warming and marked acidification; comparable rates in the future suggest the possibility of similar levels of extinctions in the future.