Ocean acidification: the local story

When people learn that carbon dioxide pollution is turning our oceans more corrosive, it’s tempting to decide that the problem is too big for any person or local government to tackle.  But as our knowledge of ocean acidification continues to evolve, it turns out that in hotspots like Washington State, local factors—from nutrient pollution to seasonal currents and maybe emissions from ships or our own traffic—are playing a role too.

As Betsy Peabody, executive director of Puget Sound Restoration Fund, put it at this week’s meeting of the state’s Ocean Acidification Blue Ribbon Panel:

This is not just the carbon story that we’ve been hearing about happening somewhere out there. It’s different. It’s here.

The bad news? These local drivers are combining with rising global carbon dioxide emissions to make local waters increasingly acidic and put the Northwest on the leading edge of destructive changes in ocean chemistry.  For example, seawater in the depths of Hood Canal is already among the most corrosive found anywhere on earth. As that trend accelerates, it could profoundly change our marine systems, what appears on our dinner plates and whether shellfish farmers and, potentially, commercial fishermen will be able to stay in business.

The good news? While Washington State can’t do much about global carbon emissions, it does have some control over the local impacts that are contributing to the problem. Figuring out what those contributors are, and where the opportunities are to better control them, is one of the tasks of the blue ribbon panel that Gov. Christine Gregoire convened to look at the problem of ocean acidification. Washington state is the first to tackle the issue, and other states whose economies depend on a health seafood industry (such as Maine) are looking to us for solutions.

The basic problem is that excess carbon dioxide causes seawater to become more acidic (although it still remains above neutral on the pH scale). These chemical changes also bind up carbonate ions, which thousands of species of marine creatures need to build shells and skeletons. As those ions become scarce, those creatures have a hard time building and maintaining those protective structures. Although responses to acidifying seas vary widely among different species, mollusks such as oysters and clams and tiny creatures at the bottom of the food chain appear particularly vulnerable so far.

Since the ocean absorbs roughly a third of the carbon dioxide emissions we release into the atmosphere, rising climate pollution is making the oceans more acidic worldwide. This longterm trend is what scientists refer to as “ocean acidification.” But there are other sources of carbon dioxide in our local waters, which are contributing factors to the problems that have already begun to affect the state’s $270 million shellfish industry.

Jennifer Langston. Ocean Acidification: The Local Story. Sight Line Daily, 24 May 2012. Article.


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