Southern Ocean dangerously acidic

Southern Ocean marine life may start to dissolve away, say Australian scientists, who have discovered that a dangerous ‘tipping point’ for ocean acidification could arrive as soon as 2030.

This is worrying news, say the experts, because organisms with calcium carbonate skeletons and shells – such as corals, pteropods, krill and other shellfish – may not be able to survive the changing water conditions.

“Our new results point to irreversible and detrimental impacts to Southern Ocean marine calcifying organisms if atmospheric carbon dioxide exceeds 450 ppm [parts per million],” said Ben McNeil, who led the team from the University of New South Wales and government research agency the CSIRO.



Tipping point

Previous work had suggested that the tipping point wouldn’t occur until atmospheric carbon dioxide (CO2) passes a concentration of 550ppm, which some climate models predict will be happen by 2060. The revised estimate is published this week in the U.S. journal, the Proceedings of the National Academy of Sciences.

Every year the ocean provides a useful service by absorbing one-third of the 30 billion tonnes of CO2 emitted into the atmosphere by burning fossil fuels.

However, researchers have shown that this dissolved CO2 creates a weak solution of carbonic acid, which is fundamentally changing the chemistry of the marine environment, with significant consequences for many marine plants and animals.

Most affected are animals that use calcium carbonate to build their skeletons. As the ocean becomes mildly more acidic (only a very slightly lower pH, still less acidic than the human body), these animals will find it more difficult to grow. Eventually, at the predicted ‘tipping point’, research suggests that they may start to find their skeletons and shells dissolve away.
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Octavia Cade, Cosmos Online, 12 November 2008. Article.

1 Response to “Southern Ocean dangerously acidic”


  1. 1 gattuso 25 November 2008 at 15:39

    The terminology used in this article is not scientifically accurate. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7”. This definition does not apply to un-manipulated seawater now nor in the foreseeable future. Hence, the adjective “acidic” should not be used. Note that there are some exceptions, for example in the immediate vicinity of CO2 vents.


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