A natural experiment in tropical waters off Papua New Guinea suggests that with increasing CO2 emissions and ocean acidification some marine organisms will benefit, but many more will lose out.

Climate scientist, Dr Janice Lough of the Australian Institute of Marine Sciences in Townsville and colleagues report their findings today in the journal Nature Climate Change.

“Even aside from thermal stress and bleaching we’re going to get progressive acidification of the oceans and this study demonstrates that is not good for maintaining healthy coral reef ecosystems,” says Lough.

“Although there are a few winners as you get higher CO2 there are many more losers.”

Increasing atmospheric CO2 levels lead to an increase in ocean acidity as the ocean absorbs some of this CO2.

“About a third of the extra CO2 that we’ve put into the atmosphere has been absorbed by the oceans and that changes the ocean chemistry,” says Lough.

The IPCC predicts that with atmospheric levels of at least 750 parts per million by 2100, ocean pH levels will drop from 8.1 to 7.8.

Short-term laboratory experiments suggest this will change the chemistry of the ocean and make it harder for coral and other organisms to form calcium carbonate skeletons.

But now scientists have real world evidence of how increasing acidity affects marine communities.

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Anna Salleh, ABC Science, 30 May 2011. Full article.