The world's corals cannot escape the inevitable impact on them caused by humanity's carbon emissions.
The warning comes from the eminent scientist who has used coral from the Great Barrier Reef to reveal disturbing changes in the chemistry of the world's oceans due to human activity.
Professor Malcolm McCulloch, a geochemist with the ARC Centre of Excellence for Coral Reef Studies and Australian National University today receives Australia's top honour for earth sciences, the Australian Academy of Science's Jaeger Medal.
"Coral can't escape the heat," he says. "Besides the effects of global warming, corals will not be able to avoid the acidification of the oceans, which is a simple and direct consequence of humanity's interference in the atmosphere. About 40 per cent of the CO2 we release dissolves into the oceans, turning them more acidic."
Analysis of corals taken from the sea off Cairns revealed an increase in acidity of as much as 0.3 pH units since the start of the industrial age, with most of it occurring in the last 50 years, he explains. If seawater acidifies only a few tenths of pH units further many corals, diatoms and shellfish will be unable to form their skeletons and shells, posing the risk of major extinctions and a threat to marine food chains.
"It's getting to the point where, besides reducing our carbon emissions humanity is probably going to have to find large-scale ways of actually removing carbon from the atmosphere," Prof. McCulloch says.
Of the currently raging political debate over carbon trading he states simply "Whatever policy Australia adopts, the outcome must be to reduce our carbon emissions. While they are small in global terms, if we take no action then big emitters like China and India will see that as a justification not to act. It is up to us to show a lead."
Prof. McCulloch warns that the ability of the oceans to soak up man-made carbon is already diminishing, raising the risk that global warming could accelerate.
Prof McCulloch is a geochemist who has made major contributions to both the study of the Earth and environmental issues. His early work at ANU opened new insights in our understanding of the evolution of the Earth's crust. Recently he has studied sea-level changes, past ocean temperatures, the impacts on coral reefs of nutrient and sediment released by human activity on land and the effects of increasing ocean acidification caused by rising CO2 levels in the atmosphere.
The Jaeger Medal commemorates the contribution of Professor John Conrad Jaeger, FAA, FRS, to Australian Earth science. The award is made to a scientist for investigations of a high order into the solid Earth or its oceans carried out in Australia or having some connection with Australian Earth science. The award is normally made every two years.
More information:
Prof. Malcolm McCulloch, CoECRS and ANU, 02 6125 9969 or 0418 447 574
Jenny Lappin, CoECRS, 07 4781 4222
Jane O'Dwyer, ANU, 02 6125 5001 or 0416 249 231