Acid test for local action

Fish recently discovered in Indonesia Much of the oceanic food web will be affected by pH changes as well as by warming

Whether you prefer the term "ocean acidification" or the less compelling but more accurate "ocean de-alkalisation", there's little doubt that the addition of carbon dioxide to the seas threatens to change them fundamentally over the course of the century.

Ocean acidification 101 says that the oceans absorb some of the extra CO2 going into the atmosphere.

That slowly makes seawater less alkali - or more acid, as you prefer - with major and potentially catastrophic impacts on sea life.

The science is well documented, so I won't go over that ground again except to raise an alert to look out for an interesting study coming out in the next few days.

If global ocean acidification from global CO2 emissions is the issue, you might think that the solution would necessarily be global as well.

That's certainly the way it's mainly been talked about - and in the long run, curbing carbon emissions probably is the only way to protect the coral and other shell-forming creatures that depend on seawater maintaining a constant average pH around 8.2.

But in an article in the journal Science this week, a group of US-based scientists and lawyers is making a different argument: local initiatives can be effective too, they say.

There are a couple of main strands to their argument.

Firstly, the pH of seawater varies from place to place; and in some coastal zones, it's already been pushed toward the acid by local pollution.


Ocean pH levels (Image: BBC)
  • The oceans are thought to have absorbed about half of the extra CO2 put into the atmosphere in the industrial age
  • This has lowered its pH by 0.1
  • pH is the measure of acidity and alkalinity
  • The vast majority of liquids lie between pH 0 (very acidic) and pH 14 (very alkaline); 7 is neutral
  • Seawater is mildly alkaline with a "natural" pH of about 8.2
  • The IPCC forecasts that ocean pH will fall by "between 0.14 and 0.35 units over the 21st Century, adding to the present decrease of 0.1 units since pre-industrial times"

Secondly, there's a large and growing mound of evidence to suggest that keeping reefs, for example, safe from disease and destructive fishing and local pollution and invasive species gives them greater resistance to climate-related threats.

A couple of years ago, in sediments around Chesapeake Bay on the eastern US coast, scientists found that the northern quahog - a type of clam whose name will resonate with fans of the Family Guy cartoon series - were in trouble.

The problem was a lack of the calcium carbonate minerals from which they fashion shells.

Putting crushed-up old shells into the sediments raised the amounts available to them, which led to an increase in the number of live clams.

One of the projected impacts of ocean acidification is a decline in the availability of carbonate, which many sea creatures extract to form aragonite and calcite.

So here in Chesapeake Bay, the authors of the Science article suggest, is evidence that localised measures could provide some defence against the global trend.

If that's a science-based approach, laws and regulations may also help.

Enforcing rules on coastal erosion, and the quality of water in rivers running into the sea, can reduce local pollution that's pushing in an acidifying direction, the article argues.

Northern quahog The northern quahog benefited from recycling

And they imply that anyone who takes an interest in the issue should scrutinise local laws to see what remedies may be available.

The US, for example, has the Clean Air Act, Clean Water Act, Coastal Zone Management Act and many others at federal and state level that might be deployable.

As discussed here a few weeks ago (and more recently by David Adam in Nature Climate Change), campaign groups have regularly attempted to use legal avenues to force action on emissions - not, it should be said, with a vast amount of success.

The latest case - an intriguing twist - has been brought by Micronesia against plans to enlarge the Prunerov coal-fired power station in the Czech Republic.

Whatever the merits of the case, it's clearly one where lawyers will have ample scope to argue about the limits of jurisdiction, the attribution of climate impacts, and indeed the scale of impacts given that projections of sea level rise are far from accurate.

Lots of the difficulties melt away when local laws are used for local change.

It might not be a strategy that solves the problem - but it could bring some relief to beleaguered bivalves.

Richard Black Article written by Richard Black Richard Black Former environment correspondent

Farewell and thanks for reading

This is my last entry for this page - I'm leaving the BBC to work, initially, on ocean conservation issues.

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  • rate this

    Comment number 66.

    Jack Hughes "pH values change from hour to hour in a fixed place.
    They vary from place to place. Sea critters cope very well with these changes"

    You have obviously never tried to maintain a salt water aquarium. If you had, you would know the pH tolerance is quite narrow and needs to be regularly adjusted to keep it high enough.

  • rate this

    Comment number 65.

    "it's a non-issue as the amount of co2 required to facilitate such a change is staggering. "

    Now LabMunkey, remember, it is not the absolute quantity, it is the concentration that shifts the direction of a chemical reaction and the concentration of CO2 has been increasing steadily (adjusted for time of year). Your assertion is BS.

  • rate this

    Comment number 64.

    This is basic chemistry. Adding CO2 to water makes it more acidic (less alkaline). All the rest of the discussion below is, quite frankly, intentional obfuscation. Regardless of whether a person agrees that CO2 is changing the climate, the ocean acidification case is clear and without reasonable doubt. Quite denying!

  • rate this

    Comment number 63.

    Is it possible that it's you that doesn't fully understand the chemistry?

  • rate this

    Comment number 62.

    Ocean acidification models combined with observations of surface pH should be enough for scientists to at least be worried about it and try to improve our understanding. Why do people have this view that because findings are not yet to a high degree of certainty then we should not be concerned. If anything the opposite is true. Hmmn I wonder what other environmental CO2 problem suffers from this..


Comments 5 of 66



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