Australia's second-largest city of Melbourne was shrouded in hazardous smoke from the country's raging bushfires on Tuesday, as scientists warned enormous blazes could become routine unless more was done to reduce the greenhouse gas emissions driving global warming.

At least 180 fires continued to burn across Victoria and New South Wales (NSW) states, with about 20 yet to be contained in NSW, Australia's most populous state.

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In Victoria five fires were at the 'Watch and Act' advice warning, one level below emergency status, authorities said.

"I wish I could say this was over, but we have a long way to go. We've got the smoke in our communities at the moment and it is at very poor or hazardous levels," Lisa Neville, Victoria’s emergency services and police minister told a media briefing.

The start of qualifying matches for the Australian Open were delayed by 90 minutes and practice suspended after air quality deteriorated to "hazardous" levels overnight.

"Conditions onsite are improving and are being constantly monitored," Tennis Australia said in a statement.

"Further decisions will be made using onsite data and in close consultation with our medical team, the Bureau of Meteorology and scientists from EPA Victoria."

Although Australia's government and parts of its media have attempted to downplay the role of man-made climate change in making the country more vulnerable to wildfires, an academic review of 57 scientific papers published since 2013 has indicated there are clear links.

"We're not going to reverse climate change on any conceivable timescale. So the conditions that are happening now, they won't go away," Richard Betts, Head of Climate Impacts Research at Britain's Met Office Hadley Centre, who co-authored the review, told a news conference in London on Monday.

The review found that climate change had led to an increase in the frequency and severity of what scientists call "fire weather" - periods with a high fire risk due to some combination of hotter temperatures, low humidity, low rainfall and strong winds.

Residents defending property from a bushfire north of Sydney in November. The fires have been burning for months and their scale has been linked to climate change [Peter Parks/AFP]

Australia has been suffering from a drought for years, and 2019 was not only the driest year ever recorded, but also the hottest.

'What climate change means'

The effects have not only been seen in Australia but also in the western United States and Canada, southern Europe, Scandinavia, the Amazon and Siberia, the review found.

Globally, fire weather seasons have lengthened across about 25 percent of the Earth's vegetated surface, resulting in an increase of about 20 percent in the mean length of the fire weather season, according to observational data.

Betts said Australia was particularly vulnerable to fires because its land area had warmed by more than the rise in average global temperature of about one degree Celsius (33.8 degrees Fahrenheit) since pre-industrial times.

The World Meteorological Organization says the global temperature increase could hit 3-5C (33.4F-41F) this century - more than three times limits agreed in the 2015 Paris Climate Agreement - if nothing is done to stop rising emissions.

"Temperature conditions in Australia are extreme at the moment but they are what we expect to happen on average in a world of three degrees of global warming," Betts said. "It brings it home to you what climate change means."

Australia's Prime Minister Scott Morrison has been under pressure over his handling of the fire crisis [David Mariuz/AAP Image via Reuters]

The review was carried out using ScienceBrief.org, a new online research platform set up by Britain's University of East Anglia and Tyndall Centre for Climate Change Research.

Pressure on government

The bushfires have been burning in Australia since September, razing 11.2 million hectares (27.6 million acres) of land; an area equivalent to nearly half the United Kingdom.

At least 28 people have died and 2,500 homes have been destroyed putting pressure on the conservative government of Prime Minister Scott Morrison to take more serious action to tackle climate change.

Morrison - who brought a lump of coal into parliament in 2017 urging MPs "not to be afraid" of the fossil fuel - has signalled the government may raise its targets for cuts to greenhouse gas emissions.

The federal government on Monday said 50 million Australian dollars ($35m) would be given to an emergency wildlife recovery programme, describing the bushfires as "an ecological disaster" that threatened several species including koalas and rock wallabies

After weeks of criticism over his handling of the crisis, Morrison has also said he would propose a high-powered inquiry into the disaster, including the effects of climate change.

Widespread rainfall is forecast on the east coast from Wednesday, which might bring some reprieve to fire-ravaged communities. The country has had a drought for three years.