Many of the articles on ocean acidification denominate it the “other carbon dioxide problem,” emphasizing that it is a discrete manifestation of rising carbon dioxide levels. However a new article in the journal Science, Yamamoto-Kawai, et al., Aragonite Undersaturation in the Arctic Ocean: Effects of Ocean Acidification and Sea Ice Melt, 326 Science 1098-1100 (2009) (subscription required), emphasizes that one manifestation of warming associated with rising levels of greenhouse gas emissions, sea ice melt, can also exacerbate ocean acidification. The researchers assessed the impacts of accelerating declines of summer sea ice extent in the Arctic Ocean during the 2000s.
Among the take-aways from the article:
- The Southern Ocean is predicted to become undersaturated with respect to aragonite by 2030, and in the North Pacific by 2100; Arctic surface waters will become undersaturated with aragonite within a decade. This is attributable to freshening related to sea ice melting and increased carbon uptake related to sea ice retreat;
- Aragonite saturation has already decreased in the top 50 meters of the Canada Basin; this is the layer in which rapid uptake of carbon dioxide occurs and increased freshwater inputs take place;
- This could have serious implications for many species of marine organisms, including coccolithophore, foraminfera, pteropods, mussels and clams. For example, aragonite shell-forming pteropods are concentrated in the top 50 meters
- Populations of both planktonic and benthic calcifying organisms in the Canadian Basin are already being affected by the rapid transition to undersaturation in the Arctic environment, another “canary in the coal mine” in terms of climate impacts.