Climate experts' hard line

Australian
Wednesday 8/10/2008 Page: 24

THE severest of the greenhouse pollution reduction targets proposed by Rudd government adviser Ross Garnaut are the minimum requirement for effective action, the country's leading climate scientists have told the Prime Minister. The scientists include Australian Research Council Federation Fellows David Karoly and Amanda Lynch, as well as Andy Pitman, all of them associated as authors and editors with the UN's 2007 Nobel Peace Prizewinning Intergovernmental Panel on Climate Change.

In his final report, released last week, Professor Garnaut proposed a 25 per cent reduction in emissions on 2000 levels by 2020 to stabilise CO2, at 450 parts per million as Australia's contribution to any global agreement. However he also proposed a 10 per cent reduction target under a 550ppm scenario, and a 5 per cent reduction target if there is no global agreement.

In an open letter to Kevin Rudd last week, 16 of the country's leading climate scientists described Garnaut's most severe target the 25 per cent option as the minimum requirement for Australia's contribution to an effective global agreement. Based on present scientific understanding, any global agreement must reduce emissions by at least 50 per cent below 1990 levels by 2050, including stabilising carbon dioxide well below 450 ppm, the 16 mainly university-based scientists said.

The UNSW's Professor Pitman, who was lead author for the IPCC group on the physical science basis of climate change, told the HES, "There's no question whatsoever that people like IPCC lead authors who do the research in the area would suggest that 450ppm is too high a value to stabilise at.

"You don't want Greenland to melt, you don't want the Antarctic ice sheet to destabilise, and you don't want the global ecosystems to fail. To avoid those things you need to stabilise at or below 400ppm." Professor Pitman said at the 450ppm level Australia would sacrifice the Murray Darling and the Great Barrier Reef.

The University of Melbourne's Professor Karoly, one of a select group of IPCC scientists asked to write a synthesis of its latest assessment report, said a stabilisation level of 550 ppm was roughly double the CO2, in the atmosphere. If this target were to be adopted it would be committing "to substantial levels of climate change including warming of the order of 2.5C to 3C above pre-industrial levels and 6m of sea level rise over a number of centuries," he said.

Professor Karoly has welcomed the priority Professor Garnaut has given to the 25 per cent target as a ''substantial change" from his interim report of a few weeks ago.

Monash's Professor Lynch, IPCC contributing author to the regional climate chapters in the past two assessment reports, told the HES the scientists believed Professor Garnaut had done "an excellent job" over the past year of characterising the issues and stimulating debate. "While he is right that Australia on its own can't achieve the mitigation required, I think that waiting for international agreement is the wrong strategy," Professor Lynch said.

Given that commercial-scale carbon capture was at least a decade away, Professor Lynch said the only immediately available approach to buy time on emissions reductions was biosequestration combined with substantial efficiency measures. She said the Co-operative Research Centre for clean power from lignite had calculated that greenhouse emissions from brown coal power stations in the Latrobe Valley are about 60 million tonnes a year and growing.

Australia could reasonably aim to offset at least 30 per cent of brown coal emissions immediately from preferably native plantations, and this should begin with funding from the auction of emissions permits under the Government's planned emissions trading scheme. Professor Lynch said the 30 per cent reduction for Latrobe Valley would require plantations equivalent to 10,000sq km.