Science tempers fears on climate change

THE world's top climate scientists have cut their worst-case forecast for global warming over the next 100 years.
A draft report by the Intergovernmental Panel on Climate Change, obtained exclusively by The Weekend Australian, offers a more certain projection of climate change than the body's forecasts five years ago.
For the first time, scientists are confident enough to project a 3C rise on the average global daily temperature by the end of this century if no action is taken to cut greenhouse gas emissions.
The Draft Fourth Assessment Report says the temperature increase could be contained to 2C by 2100 if greenhouse gas emissions are held at current levels.
In 2001, the scientists predicted temperature rises of between 1.4C and 5.8C on current levels by 2100, but better science has led them to adjust this to a narrower band of between 2C and 4.5C.
The new projections put paid to some of the more alarmist scenarios raised by previous modelling, which have suggested that sea levels could rise by almost 1m over the same period.
The report projects a rise in sea levels by century's end of between 14cm and 43cm, with further rises expected in following centuries caused by melting polar ice.
The new projections forecast damage by global warming, such as stronger cyclones, modest sea-level rises and further shrinking of the arctic sea ice.
CSIRO research predicts the biggest impact of sea-level changes of this scale would be to increase the effect of storm surges, particularly on Australia's tropical northern coastline.
The forecast temperature rises would also result in lower rainfall over most of the Australian mainland and exacerbate the threat to the survival of coral reefs and shellfish by increasing the risk of bleaching and increasing the acidity of the ocean.
Australian Conservation Foundation energy program manager Erwin Jackson said theprojections required an urgent and immediate response from the federal Government to drive accelerated investment in low-emissions technology in Australia.
"Every day we delay taking action, the problem gets worse," Mr Jackson said.
"The Government keeps throwing up the costs of action but totally ignores the costs of inaction.
"No one ever said that saving the planet would cost nothing - that's the bottom line."
A recent Australian Bureau of Agricultural and Resource Economics report on the cost of cutting greenhouse gas emissions estimated Australians would incur a fall in real wages of about 20 per cent if the nation was to unilaterally cut greenhouse gas emissions in half by 2050.
John Howard this week said that sort of scenario would have an "enormously damaging" effect on the economy. "I accept that climate change is a challenge," the Prime Minister said. "I accept the broad theory about global warming. I am sceptical about a lot of the more gloomy predictions.
"I also recognise that a country like Australia has got to balance a concern for greenhouse gas emissions with a concern for the enormous burden to be carried by consumers ... of what you might call an anti-greenhouse policy. It's a question of balance."
Federal Environment Minister Ian Campbell said the draft IPCC report was still undergoing a thorough review process before its approval by the panel next year.
"It highlights the need for an effective global response to climate change as Australia alone cannot alter the pattern of world emissions," Senator Campbell said. "We are taking a leading role internationally to achieve effective engagement by all major greenhouse gas-emitting countries."
The new projections are based on the results of 23 climate models, developed by government climate scientists from IPCC member countries.
According to current climate change models, stabilising global greenhouse gas levels to 400parts per million offers a good chance of avoiding 2C global temperature increases.
This would require global emissions to be 50 per cent below 1990 levels by 2050.
CSIRO recently concluded that the goal of 60 per cent reductions might be considered the minimum needed to avoid dangerous climate change.
Any further reductions in global temperatures would require cuts in emissions of about 80-90 per cent in industrialised countries by 2050, which would require a faster transition to near-zero emissions technologies.
The Kyoto Protocol is an international agreement for developed countries to meet greenhouse gas emissions targets by 2012.
Australia and the US have refused to sign the protocol, instead proposing a global climate pact that focuses on working with developing countries such as China and India to reduce their greenhouse emissions.
Mr Jackson said the IPCC draft report highlighted the inadequacy of Australia's policy response to the threat of climate change.
"If these projections become a reality, our children face living in an Australia with no Barrier Reef, no Kakadu wetlands and a Murray River reduced to a trickle."