As people in fire prone areas across New South Wales review their survival plans or flee for their lives, Australian Prime Minister Tony Abbott has said he is convinced there is no link between bushfires and climate change.

"Fire is a part of the Australian experience," Mr Abbott told Melbourne radio listeners. "It has been since humans were on this continent.... Climate change is real as I have often said and we should take strong action against it but these fires are certainly not a function of climate change. They are a function of life in Australia."

To make his point, Mr Abbott rattled off a series of years when Australia had experienced bad bushfires. He also said that Christiana Figueres, executive secretary of the UN Framework Convention on Climate Change, was "talking through her hat" when she pointed out earlier this week that there was a link between bushfires and human-caused emissions of greenhouse gases.

In making his statement, Mr Abbott has dismissed out of hand the work of scientists going back more than 25 years showing that as temperatures and carbon dioxide emissions go up, so do the risks of bushfires. Christiana Figueres' hat is stuffed with evidence.

New South Wales burns in October

In the lead up to the current tinder box-conditions in New South Wales, Bureau of Meteorology records show the state had recorded its hottest September on record. The state also experienced its warmest start to a year, with the temperature from January to September 1.36C above the historical average. September also marked the end of Australia's hottest 12 month period on record, which came after the hottest calendar year on record.

When weather and fire authorities issue warnings about the risk of fire in Australia, they use what's known as the McArthur Forest Fire Danger Index - or FFDI for short.

The index produces a number that corresponds to a warning level. Zero to 11 means the risk of fire is low to moderate. From 75-99 the risk is "extreme". After the horrific 2009 Black Saturday bushfires in Victoria, a further category of "catastrophic" was added for times when the FFDI comes up with a number of 100 or higher.

This index, developed in the 1960s, combines the most important factors that create the perfect conditions for fire. They are temperature, wind speed, rainfall and the dryness of the fuel - that is, the grasses, trees and undergrowth.

Importantly, FFDI also looks at how dry the air has been (relative humidity) because drier air and higher temperatures are what "cures" the fuel for the fire.

What's been happening to fire weather?

A study last year in the International Journal of Climatology looked at the FFDI data from 38 sites around Australia from 1973 to 2010. None of the sites showed a reduction in fire danger and 16 of them showed that fire weather had increased significantly. While the study was not set up to find a link between human-emissions and bushfires, the study said the trends were "consistent with projected impacts of climate change on FFDI".

The study, carried out by scientists from the NSW government, the CSIRO and the Bureau of meteorology, also found that the most distinct increases in fire risk were in spring and autumn, meaning the fire season was getting longer.

In 2007, a study by scientists at the CSIRO, Bureau of Meteorology and a government-backed bushfire research centre also found that Australia was experiencing more dangerous fire-prone days. The study found:

Increases of 10-40% between 1980-2000 and 2001-2007 are evident at most sites. The strongest rises are seen in the interior portions of NSW, and they are associated with a jump in the number of very high and extreme fire danger days.



The study also pointed out there was a strong correlation between increased risk of fire and periods of drought. Times of higher bushfire risk also tended to happen during periods of El Nino, which in Australia is associated with hotter temperatures and less rain.

Professor Roger Jones, a co-ordinating lead author for a chapter in the next major IPCC report looking at climate impacts, has written about his own study into fire danger trends in the state of Victoria, which has already had a flush of damaging bushfires. He found that " fire danger in Victoria increased by over a third after 1996, compared to 1972-1996."

Professor Jones, of Victoria University, also points out that recently observed changes in fire risk are already at the "worst case" level predicted for the year 2050 by a previous study. He writes:

We can't consider severe fires as one-offs that happen every few decades. If they're becoming a systemic part of our environment we have to consider this really seriously. There will be a financial cost and a human cost, and we will see it repeated, if we don't plan ahead.

What about the future?

Twenty-five years ago, what's thought to be the very first scientific paper in the world suggesting global warming could increase the risk of bushfires was published in Australia (to give you an idea of how long scientists have been looking at this, 1987 was also the year that Aussies got a cell phone network, the year Fred Astaire died and the year Argentinian footballer Lionel Messi was born).

That first study was carried out by Dr Tom Beer, who is still at CSIRO where he was back in 1987. Beer's research was prepared for a government-backed conference in Melbourne, where about 100 scientists and engineers presented their research into the potential impacts of "greenhouse-induced climatic change" to an audience of more than 250 people

Beer examined almost 40 years of meteorological data from three sites and then used a computer model to project what would happen if average temperatures in those areas went up between 3.5C and 4C. He found, not surprisingly, that the risk of fire went up. Dr Beer remembers the significance of this pioneering study, telling me:

Scientifically I recall being invited to meetings in the US to discuss our results which led to various US researchers undertaking similar studies in relation to the North American fire situation. There was considerable media interest in the Greenhouse conference and I was interviewed by one journalist who later told me that there was more interest in this story than in any previous story she had written.



Beer followed up his study in 1995, but this time used more sophisticated modelling to look at how fire danger changed as levels of carbon dioxide in the atmosphere went up. He says:

The 1995 study using two computer models of the effects of doubled CO2 confirmed the results of the 1988 paper for south-eastern Australia, and also confirmed that the results of the 1998 paper (an increase in fire danger index with an increase in CO2 levels) was true for almost all of Australia. The models were ambiguous as to the situation in Northern Australia. The models also confirmed the link between relative-humidity and fire danger index in south-east Australia, but indicated that even in some areas of Australia where the computer models predicted an increase in relative humidity, the fire danger was still predicted to increase.



Since then, there have been multiple studies which have almost universally suggested the same thing. As temperatures and CO2 in the air goes up, so to does the risk of bushfires.

When Prime Minister Abbott says that bushfires are a "function of life in Australia" he's clearly correct, but to declare so confidently that bush fires are not linked to climate change in the face of so much evidence to the contrary, suggests denial.

If Tony Abbott thinks Christiana Figueres is "talking though her hat" then from where is Tony Abbott talking? Answers on a postcard please.