Carbon dioxide threatens marine life (audio)

TONY EASTLEY: There’s alarming evidence that increased levels of carbon dioxide in the atmosphere are harming ocean-based animal life.

When CO2 enters the atmosphere it’s absorbed by the ocean causing increased acidity in the water.

A new study has found a link between this process and a decrease in the shell-making ability of microscopic marine organisms.

Michael Edwards has this report.

MICHAEL EDWARDS: The earth’s oceans act as a virtual sponge for carbon dioxide emissions.

When the CO2 is absorbed into the water, it becomes an acid, causing ocean acidification.

Normally, the ocean has mechanisms to balance this out.

But according to Dr Will Howard from the Antarctic Climate and Ecosystems Co-operative Research Centre, industrialisation has changed the natural balance as more CO2 than ever before has been pumped into the atmosphere.

WILL HOWARD: The balance is changing because we are putting fossil fuel, carbon dioxide into the atmosphere at a rate much greater than any natural process would.

The ocean and the atmosphere have natural exchanges of carbon dioxide, however we’re taking carbon dioxide that’s been stored for millions of years and putting it into the atmosphere very suddenly, in fact, much more quickly than, as we understand it, any exchanges have occurred in about the last million years or so.

MICHAEL EDWARDS: And for the first time a team of scientists from the ACE Centre, led by Dr Howard, has found a direct link between ocean acidification and a deterioration in animal life.

The team studied the shell weights of microscopic marine animals in the Southern Ocean. It found that modern shell weights are up to 35 per cent lower than in older organisms.

Dr Will Howard says the results from the Southern Ocean are a good indication of a process that is spreading across the globe.

WILL HOWARD: We see that they’re making thinner and lighter shells. These are calcifying organisms who construct a shell out of calcium carbonate, the same type of material that limestone, coral structures are made out of and it’s very, very sensitive to the chemistry of water.

MICHAEL EDWARDS: The research indicates the changes coincide with widespread industrialisation which began a century ago.

WILL HOWARD: It’s consistent with the impact that we would expect from what we know about the carbon dioxide that’s come into the ocean since the industrial era began.

MICHAEL EDWARDS: And Dr Howard says there are serious implications for the entire ocean ecosystem.

WILL HOWARD: There are certainly strong implications for the carbon fluxes in the ocean because their shell-making abilities are part of what transports carbon. Their shells are somewhat denser than some of the other sources of carbon. Their shells are part of what transport carbon from surface ocean and thus from the atmosphere into the deep part of the ocean.

So their ability to make shells is actually an important part of the ocean’s ability to store carbon, especially anthropogenic carbon that comes from fossil fuel emissions.

TONY EASTLEY: Dr Will Howard from the Antarctic Climate and Ecosystems Co-operative Research Centre ending Michael Edwards’ report.

Michael Edwards, ABC Local Radio, Australia. 9 March 2009. Article and audio file.

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