July 22, 2013 — Ocean acidification, known to scientists as “the other CO₂ problem”, may cause changes to our marine fauna—including severely depleted cod—that we have only begun to wrap our heads around.
Ocean acidification is caused by the rise of atmospheric carbon dioxide from the burning of fossil fuels. As this excess carbon dioxide dissolves in ocean water, carbonic acid is formed, increasing the concentration of hydrogen (H+) ions, and lowering pH. These chemical reactions also consume carbonate ions, an essential building block for many shell-building organisms, which use various forms of calcium carbonate to create their shells or skeletons. Collectively, these changes in ocean chemistry are known as ocean acidification.
Global ocean pH has already dropped 0.1 units, from 8.2 to 8.1 since the Industrial era. Though this seems like a very small change, pH is measured on a logarithmic scale, and represents a percent change in hydrogen ion concentration. A change of 1 unit pH thus represents a change ten-times as large in hydrogen ion concentration. Thus, the ocean’s pH change in the past century actually represents a 30% increase in acidity, and is projected to fall another 0.3-0.5 units- up to a 300% increase in acidity.
Scientists have begun to study the effects of elevated CO₂ levels on certain species to try and gauge how acidifying waters will affect marine-dwelling organisms. Reactions to acidified conditions vary widely. The news is good and bad, but mostly bad. A few corals and other marine species can survive elevated CO₂, but most seem unable to adapt quickly enough to keep up with the changing ocean. Acidification is especially hard on very young shelled organisms, on certain phytoplankton, and on reef-building corals. Many species exhibit reduced ability to build their shells, or even dissolution of shell material in experimental conditions.
Read the full story from the Conservation Law Foundation at Talking Fish