In trouble: Antarctic krill are increasingly at danger as the effects of climate change alter their ecosystem. Photo: Australian Antarctic Division
Turns out it's the little things we need to worry about in climate change. When they are in trouble a great polar ecosystem might also be having problems.
The oceans are absorbing so much carbon dioxide that they are acidifying at an unprecedented rate, the International Program on the State of the Oceans said.
Foraminifera: Single-celled marine protozoa threatened by the acidification of the oceans waters. Photo: Getty Images
Geological records show the current acidification is unparalleled in at least the last 300 million years, IPSO's latest report said. ''We are entering an unknown territory of marine ecosystem change, and exposing organisms to intolerable evolutionary pressure.''
The smallest of these creatures in the Antarctic marine ecosystem are said to be showing some of the early signs of acidification damage. And work by Australian scientists shows even greater problems lie in store for the creature at the centre of the Antarctic food web - krill.
Coalition Environment Minister Greg Hunt said warnings of increasing ocean acidification were the most important new advice from the Intergovernmental Panel on Climate Change's latest report.
''In the debate around climate change, research on acidification of the oceans is a particular personal concern,'' Mr Hunt said. ''This has been reinforced by the work of Australian scientists, particularly in the Antarctic.
''The Southern Ocean is specially vulnerable to increased acidity because of the cold water and the type of marine life. If there are changes in these environments, then there is a flow-on impact across the entire marine system.''
The Oxford-based IPSO scientists reported widespread global biological impacts, including the erosion of coral reefs, tipping past their building rates as soon as 2030-2050.
But the rate of acidification is 50 per cent faster in the higher polar latitudes than in sub-tropical waters, due to the effects of temperature on ocean chemistry, it said.
''Think of it like a cold beer at a barbecue," Donna Roberts of the Antarctic Climate and Ecosystems CRC at the University of Tasmania said. ''It holds on to its carbon dioxide bubbles longer.
''Remember that 40 per cent of all the carbon dioxide going into the oceans goes into the Southern Ocean. It's going to hit high, and hit hard,'' she said.
Dr Roberts said work on pteropod snails showed distinct acidification effects. ''We're finding evidence that shell structure has been getting softer since 1997.''
Similar problems face foraminifera, countless micro-organisms which also rely on calcium carbonate for their structure.
But it is the keystone Antarctic species, the shrimp-like krill, that is a focus of concern about future acidification.
Biologist So Kawaguchi said Antarctic krill were already experiencing changing climate stressors such as rising temperatures and changes in their planktonic food production.
In an aquarium world with carbon dioxide elevated at predicted rates, krill eggs failed to develop properly, Dr Kawaguchi said.
If emissions were to continue to rise, harm would increase during coming decades to the point where by 2300, krill would be unable to hatch in vast areas of the Southern Ocean.
Chief scientist at the Antarctic Division, Nick Gales, said work was beginning on the flow-on effects of the loss of krill.
''Animals that don't have the flexibility to prey switch are likely to be more in trouble,'' Dr Gales said.
''Among the whales, it would be the blue whale and the Antarctic minke which are reliant on krill. And there is a whole range of seabirds.''
Correction: The original version of this story referred to tetrapod, rather than pteropod, snails.