The Pathology of Acidification:
An Ocean Cancer?

by Malin Jennings

One of the problems with the term “climate change” is that it’s incomplete. It addresses the impact of the phenomenon on our atmosphere, but ignores the changes underway in our oceans.  And those changes are important.

About half of the carbon dioxide produced by burning fossil fuels is absorbed by the oceans equivalent to a 30% increase in the concentration of hydrogen ions[1], with most of it remaining near the surface. Once in seawater it undergoes a chemical transformation and in high enough concentrations, can behave like an oceanic cancer.

Though the alkaline reductions we’ve experienced so far are relatively small, they have already triggered a range of problems.  Coral and other carbonate-shelled sea life are finding it harder to form their calcium carbonate exoskeletons.  It’s believed that some ocean areas will be so corrosive by 2100 that the minute pteropod snails -- so critical to the marine food chain -- will be unable to form shells.  Acidic conditions are already driving out the symbiotic algae that give coral its distinctive color, a process known as bleaching. And there are places where marine creatures are managing to develop shells, only to have them disintegrate in acidic water, like chalk in a glass of vinegar. 

Of particular concern are calcified organisms in deep, cold waters, where carbonate ions, affected by pressure and temperature, create a more acidic environment.  Should acidification continue apace, it will be harder for these organisms, like aragonite pterapods, to grow and survive, especially in the Polar Regions. 

It’s not known how much damage can occur to these marine snails before disruptions are felt further down the food chain.   A recent report (Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Future Research) concludes that the ocean’s natural acid balance has already been upset.  Christopher Sabine, a co-author of the report, estimates that so far the oceans have absorbed about one third of all of the fossil fuel emissions produced, about 118 million tons  of CO₂ .    The report lays out research steps that the authors believe should be pursued in the next five to ten years, including:

• Monitoring the calcification of pterapods, corals and other shelled sea life

• Studying the potential downstream consequences to sudden drops of shelled organisms

• Determining the effects of seasonal warming and cooling on acidification

Reducing CO₂ emissions into the atmosphere appears to be the only practical way to minimize the risk of large-scale and long-term changes to the oceans. The point is that there is a direct correlation between carbon dioxide output and ocean acidity and it’s rendering more and more of the ocean inhospitable to marine life at the very base of the food chain.  Initially, the die offs are being seen in surface waters, where most of the absorbed CO₂ resides.  But researchers recommend that we accelerate our study of the phenomenon to better understand what will happen if  -- and when --  it metastasizes throughout the ocean.