World’s oceans face an acid test

Carbon dioxide emissions from modern society are turning the ocean more acidic and some sea creatures are already suffering, according to research to be discussed at a major global science conference.

Studies in the Southern Ocean by Australian scientists found that the shells of tiny amoeba-like creatures called foraminifera have become thinner since the Industrial Revolution.

The scientists say this shows that increasing CO2 uptake in the ocean has a direct effect on the ability of micro-organisms to make shells.

The paper, being presented at the University of Copenhagen’s International Scientific Congress on Climate Change, will add to a rising tide of scientific concern over ocean acidification.

Already, ocean acidity has increased about 32% since pre-industrial times. By 2100, it is projected to have increased by perhaps 130%, which scientists fear could have a potentially catastrophic impact on marine life.

In a study published in Nature Geoscience, William Howard, Andrew Moy and colleagues collected the shells of the organisms as they fell towards the sea floor.

They compared the mass of the shells, about the size of a grain of sand, to the mass of older shells on the sea floor.

The modern shells were 30 to 35% lighter than those that formed prior to the industrial period.

The researchers from the University of Tasmania attribute the change to the acidification of the Southern Ocean, which they say is driven by the uptake of CO2 from factories, cars and power stations.

Mussel test

Other scientists are wary of attributing all the blame for the acidification of the Southern Ocean on humans – there is major upwelling of more acidic water from the deep seas.

Waters from the deep ocean are colder than the surface waters and contain more carbon, which mixes with the seawater to form carbonic acid.

But this will not diminish concern over the problem of ocean acidification in general.

Some of the cutting-edge work in this new field of science is being done at Plymouth Marine Laboratory (PML) in south-west England.

Roger Harrabin, BBC News, 10 March 2009. Full article and video.

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