Tighter timeline for ocean organisms

ELEANOR HALL: Now to that alarming research on marine life in the southern ocean which shows that the tipping point where animals will struggle to survive will come sooner than scientists previously thought.

Researchers at the Climate Change Research Centre at the University of New South Wales are warning that acidity in the Southern Ocean will reach destructive levels where it will dissolve the shells of marine organisms by 2030.

As Jane Cowan reports that is at least twenty years earlier than scientists had previously predicted.

JANE COWAN: When you’re a marine organism with a shell made out of calcium carbonate, one thing you don’t want is an acidic ocean.

BEN MCNEIL: I guess dangerous is not really, it’s a sort of subjective word really. But I guess dissolving shells is definitely a consequence which would be quite problematic for a number of these organisms.

JANE COWAN: That’s Senior Research Fellow Dr Ben McNeil from the Climate Change Research Centre at the University of New South Wales. He’s the one who made the unsettling discovery. The problem is carbon dioxide in the atmosphere. As humans pump billions of tonnes of it into the air, oceans absorb it and become more acidic.

Previous estimates predicted the shells of microscopic zooplankton for instance would start to dissolve when carbon dioxide concentrations in the atmosphere reached 550 parts per million, something that was anticipated to happen around the middle of the century.

But Dr Ben McNeil has found that point will be reached when carbon dioxide in the atmosphere hits 450 parts per million; something that could happen as soon as 2030.

BEN MCNEIL: And the reason is that during winter in autumn in the Southern Ocean there are some circumstances which lower the PH levels quite significantly naturally and so we didn’t realise there was such a large natural variation just throughout the year.

When you take that into account, coupled with what we’re putting up into the atmosphere that brings forth these problematic conditions a lot earlier.

JANE COWAN: Dr McNeil says if acidification can’t be sufficiently slowed, the organisms will just have to adapt and fast.

BEN MCNEIL: I guess they’re out on their own really, I’m not sure what we can do in terms of particular organisms in the Southern Ocean if we get to 450. They’ll have to, hopefully they can adapt to those changes and maybe migrate north where there isn’t the problems that are associated in the Southern Ocean.

JANE COWAN: But migration and adaptation aren’t options for some of the deep sea coral ecosystems most at risk. Ecosystems like those discovered by Dr Martin Riddle from the Australian Antarctic Division on a voyage last year.

MARTIN RIDDLE: We discovered a very biologically diverse cold water, cold community ion the edge of the continental shelf of the coast of Antarctica. They can’t go any shallower, they can’t just migrate up the slope because they’re old, slow growing animals that are highly susceptible to disturbance from ice bergs to they can’t live any shallower, but if that environment changes, we may well loose them.

JANE COWAN: The scientists agree these findings emphasise the need to keep carbon dioxide levels in the atmosphere below 450 parts per million. Researcher Dr Ben McNeil says reducing emissions across the globe by 60 per cent by 2050 would keep carbon dioxide concentrations within those levels.

But he says the inability of developing countries to make such heavy cuts means developed nations like Australia need to increase their targets to 80 per cent by 2050 to achieve 60 per cent overall.

BEN MCNEIL: I think the developed world will be starting to or need to take stronger action quicker to get to where we need to be and I know that the new Obama Administration has 80 per cent by 2050 target.

JANE COWAN: That’s something oceanographer Dr Will Howard from the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart would like to see.

WILL HOWARD: If you really wanted to protect the ocean from ocean acidification let us say in winter when these impacts would be felt, then you would have to in theory set much sharper lower targets.

ELEANOR HALL: That’s oceanographer Dr Will Howard, ending Jane Cowan’s report.

Jane Cowan, http://www.abc.net.au, 11 November 2008. Article.

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