The shells of tiny single-celled organisms in the Southern Oceans are thinning due to acid-forming carbon dioxide being absorbed by oceans, new research has found.

Organisms the size of sand grains are helping scientists to document the problem of ocean acidification (Source: ACE CRC)

Dr Will Howard of the Antarctic Climate & Ecosystems Cooperative Research Centre and colleagues report their findings today in the journal Nature Geoscience.

"The ocean is currently taking up somewhere in the neighbourhood of a third of our fossil fuel emissions," says Howard, a palaeo-climatologist.

Scientists have predicted this absorption of carbon dioxide would boost the acidity of oceans and interfere with the ability of some marine species to build their shells.

"It was predicted and now we're seeing it," says Howard. "This is not an issue for the future any more. This is an issue for now."