Climate change is already increasing the intensity and severity of bushfires in New South Wales and extending bushfire season by months, a report by the Climate Council has warned.



The economic cost of fires such as those that devastated the state’s Blue Mountains one year ago will triple by mid-century and the number of professional firefighters will need to double, the commission said, urging that carbon emissions be cut “rapidly and deeply” in order to reduce the risk of conditions becoming even hotter and drier.

It noted that 2013 was Australia’s hottest year on record and last summer was the driest Sydney had experienced in nearly three decades. “These conditions are driving up the likelihood of very high fire danger weather in the state,” the report said.

More than 50 local councils in the state announced the beginning of bushfire season before its official start in October, some as early as August, a month in which about 90 bushfires burned simultaneously and several properties were lost.

The CEO of the Climate Council, Amanda McKenzie, said that recent years had seen the introduction of a new category of fire warning. “We saw in Black Saturday [in Victoria in 2009] a new fire weather warning, of ‘catastrophic conditions’, and we’ve seen that spread to South Australia, Tasmania and New South Wales. These are new types of fires,” she said.

She said the longer fire seasons meant that crucial hazard-reduction measures sometimes couldn’t be carried out. “There’s a narrowing of time in which there’s safe conditions to conduct hazard reduction, such as backburning and fuel clearing,” she said.

The report said bushfire risk is exacerbated by a “long-term drying trend” as a result of decreasing rainfall in southeast Australia since the mid-1990s. The Bureau of Meteorology has predicted that the next three months will be “drier than normal”, reducing soil moisture and leading to a buildup of logs and forest debris that can be easily ignited.

The council, which was defunded by the Abbott government last year and resurrected with crowdsourced funding, directly addressed the link between climate change and bushfires – which prime minister Tony Abbott has described as “complete hogwash”.

It says climate change plays a “relatively small” role in actually igniting bushfires, which are more likely to be deliberately lit or sparked by lightning.

“Very hot, dry and windy days create very high bushfire risk. The most direct link between bushfires and climate change therefore comes from the relationship between the long-term trend towards a warmer climate due to increasing greenhouse gas emissions ... and the incidence of very hot days,” the report said.

“Put simply, climate change is increasing the frequency and severity of very hot days and is driving up the likelihood of very high fire danger weather.”

It notes: “Asking if a weather event is ‘caused’ by climate change is the wrong question. All extreme weather events are now being influenced by climate change because they are occurring in a climate system that is hotter and moister than it was 50 years ago.”

Guardian Australia reported in June that the environment department’s official advice on extreme weather had been altered to remove mention of the link between climate change and events such as bushfires and heatwaves.

Among the changes, a passage reading, “There is a growing and robust body of evidence that climate change will increase the frequency and intensity of extreme weather events,” had been removed in favour of a general explanation of what extreme weather is.

The federal environment minister, Greg Hunt, was ridiculed last October for citing a Wikipedia entry to dismiss the link between bushfires and climate change.

McKenzie said that bushfires had always been a part of Australian life, “but what’s happening is that climate change is worsening bushfire conditions, so there’s a clear link between them”.

The latest IPCC assessment, released in March, found with “high confidence” that higher temperatures and drier conditions would lead to “increased damages to ecosystems and settlements, economic losses and risks to human life from wildfires in most of southern Australia and many parts of New Zealand”.