Download - ARC Centre of Excellence for Coral Reef Studies

Media ReleaseOcean breakthrough onglobal warmingA major discovery in Program 1 has opened the way for researchers to measure the ability ofthe world’s oceans to absorb man-made CO 2- a key factor in global warming. The discoveryby Professor Malcolm McCulloch, deputy director of the Australian Research Council Centre ofExcellence for Coral Reef Studies (CoECRS) and colleagues from Italian research institutionsled by Dr Paolo Montagna, will allow researchers to see far into the past to understand thebiological and chemical makeup of the oceans. This may solve one of the biggest questionsfacing global warming: whether or not the oceans can keep pace with human CO 2output.Professor McCulloch’s findings are published in 2006 in the international journal Science. They reveal a wayto calculate the amount of phosphorus, a nutrient of vital importance to all life.“Now that we have this tool we can look more closely at the role of nutrients in the ocean and try andunderstand, in a lot more detail, how they operated in the past,” says Prof. McCulloch. “We can now fi ndout how the oceans responded to previous increases in carbon dioxide (CO 2) and how quickly they canabsorb it,” he says.The tool could help answer one of the biggest questions in the global warming debate: whether the‘biologic pump’, through which the oceans naturally absorb CO ²from the atmosphere, can keep pace withthe vast amounts now being produced by humans.Plants and animals in the oceans’ surface waters drive the ‘biologic pump’ by taking up much of the CO 2from the air and storing it inside their bodies. Eventually the CO ²stored in their bodies descends to thedeep ocean and becomes part of the sea fl oor. The turbulent mixing of the oceans also helps to absorb CO 2.Scientists fear that if the ‘biologic pump’ cannot keep up with human CO 2emissions, the waters of theoceans will become more acid. This could hinder the growth of coral reefs, and may also be detrimental toother plants and animals that are critical to the operation of biological pump, which could ultimately lead tothe collapse of one of the main systems that helps to remove greenhouse gases from the atmosphere.The more plants and animals in the ocean the more productive it becomes and the more the ‘biologicpump’ can absorb greenhouse gases. The productivity of an area of ocean is indicated by the amount ofphosphorus in it. “Phosphorus is a key nutrient in the ocean that limits or controls biological productivity.Organisms use it up and because there is only so much available, there is a limit to how many organismsthere can be,” explains Prof. McCulloch.“We can go back in time and look at the past history of the earth and look at how it reacted,” saysMcCulloch, “This complements ongoing studies of our oceans, because the dilemma is that you often don’tknow whether we are in an irreversible situation till after it has happened, so we try to better understandthese processes by looking at how the planet has responded in the past.”This view into the past is made possible because of Prof. McCulloch’s discovery that the preservedskeletons of ancient deep sea corals store phosphorous in exactly the same amounts as the surroundingoceans. By using sophisticated and accurate dating methods on the corals he can piece togetherinformation on the oceans as far back as the last glacial period, nearly 20 000 years ago.Prof. McCulloch plans to use the newly discovered tool in future studies to provide a ‘health check-up’of the biologic pump in order to see whether it will be able to keep up with the rate of greenhouse gasemissions from humans.5 July 200615