Researchers find emissions destroy Southern Ocean marine life
Radio Australia 11 Nov 08;
Australian scientists have estimated that carbon emissions will start destroying marine life in the Southern Ocean in just over 20 years time.
Our reporter Nonee Walsh says the world's oceans absorb carbon dioxide, and are becoming more acidic.
A University of New South Wales researcher Ben McNeil has factored in seasonal variations, and found acidity levels in the Southern Ocean will damage tiny ocean organisms, sooner than previously thought.
"They start to dissolve. One is called a tetrapod - swimming snails, and they form the basis of the food chain. It has the effect of amplifying bringing forward the onset of these problematic conditions for these particular species."
Dr McNeil's tipping point is expected to be reached in 2030, when global atmospheric carbon is 15 percent higher than it is now.
Terminal diagnosis for ocean creatures
Richard Macey, Sydney Morning Herald 12 Nov 08;
RISING acid levels in the Southern Ocean will start destroying sea life within 30 years, three decades earlier than previously thought, Australian climate change researchers warned yesterday.
Much of the carbon dioxide pumped into the atmosphere by human activity is absorbed by the oceans, causing the sea water to become more acidic.
Scientists had previously predicted that when carbon dioxide in the atmosphere reached 550 parts per million - compared with about 383 parts per million today - the oceans would become so acidic that the calcium in the shells of sea creatures would start dissolving. However, it was thought it would take 60 to 100 years for such a "tipping point" to be reached.
But new findings by Ben McNeil, of the University of NSW, and the CSIRO's Dr Richard Matear, suggest rising acidity may trigger "irreversible" destruction of shell creatures far sooner.
Dr McNeil said yesterday that the earlier predictions had been based on average annual atmospheric carbon dioxide projections. They overlooked the impact of seasonal variations in the Southern Ocean.
Every winter, Dr McNeil said, strong winds stirred the Southern Ocean, causing cold water from deeper than 500 metres to be pushed towards the surface.
"The process is known as an upwelling," Dr McNeil said, adding that the rising water dragged up carbon dioxide dissolved by the sea up to 50 years ago.
The carbon dioxide-rich rising water then mixed with surface water and absorbed the greenhouse gas from the atmosphere, amplifying acid levels.
The scientists calculated that in winter, when upwelling peaks, the Southern Ocean would become acidic enough to dissolve the shells of some sea life when atmospheric carbon dioxide levels reached just 450 parts per million.
If current trends continued, Dr McNeil said, that would happen within 30 years.
He predicted that pteropods, "swimming snails" just a few millimetres long that form part of the base of the ocean's food chain, would be among the first to die as their shells contained the delicate mineral aragonite, which dissolved quickly in relatively low acid levels.
The Federal Government's climate change adviser, Professor Ross Garnaut, in his report in September, backed pegging carbon dioxide levels to 550 parts per million, arguing that world leaders were not ready for any tougher agreement holding levels to no more than 450 parts per million, a ceiling supported by many European scientists.
