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ENVIRONMENT-AUSTRALIA: Bushfires Highlight Global Warming Danger

Stephen de Tarczynski

MELBOURNE, Feb 17 2009 (IPS) - While the bushfires which ravaged parts of the state of Victoria earlier this month – the most devastating in the nation’s history – are not being blamed directly on the effects of climate change, it is clear that global warming was indeed a factor.

“In terms of the temperature component of the fire weather on Feb.7, I think we can say that increases in greenhouse gas conditions are partly responsible,” says Kevin Hennessy, leading climate scientist.

Hennessy, who is principal research scientist with the climate change risk, adaptation and policy team at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, told IPS that the fires were due to the extremely hot, windy and dry conditions of early February.

“The very warm conditions are part of a warming trend since at least 1950. The international consensus is that it’s very likely that most of that warming is due to increases in [human-induced] greenhouse gases,” says the scientist who was the coordinating lead author of the Australia and New Zealand chapter of the 2007 Intergovernmental Panel on Climate Change (IPCC) report on impacts, adaptation and vulnerability.

Temperatures in some parts of Victoria reached into the high 40s on Feb.7, with Melbourne experiencing its hottest day on record – records were first kept from 1855 – with a top of 46.4 degrees Celsius. This heat was preceded by several days of temperatures into the mid-40s in late January.

Bushfires have been part of the country’s landscape for millions of years and are particularly common in the savannas of northern Australia, yet the southeast of Australia, where the majority of the population lives, is also susceptible to major wildfires.

The twentieth century witnessed numerous deadly bushfires in the nation’s southeast, including 1939’s ‘Black Friday’ fires which killed 71 in Victoria, Tasmania’s 1967 fires in which 62 were killed, and ‘Ash Wednesday’ in 1983, when 76 people lost their lives in fires across Victoria and South Australia.

As horrific as previous fires in the region have been, however, this month’s blazes, some of which continue to burn, have eclipsed all in terms of loss of life and destruction.

So far, 200 people have been confirmed dead – the death toll is expected to rise as authorities continue to search through fire-ravaged towns – and an estimated 7,000 people left homeless from the fires that have destroyed more than 450,000 hectares of forest, farms and even towns to the north and east of Australia’s second largest city, Melbourne.

But while Hennessy does not attribute the strong, hot, fire-spreading north-westerly winds which combined with the extreme heat to reduce the vegetation’s moisture content – thereby making the bush more combustible – directly to the warming of Australia, the scientist does believe there is a link.

“The very extreme wind conditions, while not directly related to climate change, are affected by how hot the continent is compared to how cold the oceans are. That temperature gradient was very, very strong on Feb.7 this year,” he says.

And although the ongoing drought in southeast Australia has contributed to drying out the region’s vegetation, Hennessy warns that uncertainty remains over whether climate change is a factor in the drought which has so far lasted for 12 years.

“While there may be a large proportion of [rainfall changes] due to natural variability there is also the possibility that human-induced greenhouse gas conditions play a role. But that has not been quantified at this stage,” he told IPS.

While February’s fires may be shocking in their level of destructive power, they are part of an overall trend which has seen an increase in “fire weather” – quantified as a combination of temperature, relative humidity and wind speed with rainfall – in the past few decades.

A study conducted in 2007 by the CSIRO, the Bureau of Meteorology and the Bushfire Cooperative Research Centre titled Bushfire Weather in Southeast Australia found that most of the very intense fire weather seasons have occurred since the late 1990s.

The report, commissioned by the Climate Institute research organisation, says that the increased risk of fire danger is likely to be due to a combination of natural climate variability and human-induced climate change, the relative importance of which is still to be determined.

The report warns that this upward trend in the frequency of fire weather is set to continue.

While changes in annual total fire weather was projected to increase from a 1990 baseline by zero to10 percent by 2020 and zero to 30 percent by 2050, it is perhaps the anticipated changes in the number of “very-high” and “extreme” fire weather days – the extreme rating indicates scenarios in which fires quickly become uncontrollable and are very difficult to extinguish prior to changes in weather conditions – that is most alarming.

Very-high fire weather conditions are projected to increase by between two and 30 percent on 1990 levels by 2020 and by between five and 100 percent by 2050. The number of days of extreme fire weather, meanwhile, is expected to rise by five to 65 percent by 2020 and from 10 to 300 percent by 2050.

In an open letter to Prime Minister Kevin Rudd and Victorian Premier John Brumby on Feb.12, the national secretary of the United Firefighters Union of Australia, Peter Marshall, attacked the government’s target of reducing greenhouse gas emissions by just five percent on 2000 levels by 2020.

“Given the Federal Government’s dismal greenhouse gas emissions cut of 5 per cent, the science suggests we are well on the way to guaranteeing that somewhere in the country there will be an almost annual repeat of the recent disaster and more frequent extreme weather events,” wrote Marshall in the letter published by Fairfax newspapers.

And if recent comments by Professor Chris Field are correct – the leading member of the IPCC said recently that previous research on climate change dramatically underestimated the severity of global warming – then even the most dire predictions of bushfire danger in Australia’s southeast may be surpassed.