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Australia Bushfires

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Mike
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Australia Bushfires

Сообщение Mike » Вс ноя 24, 2019 1:24 am

Are this year's fires unprecedented? Conservative commentators have pointed to a long history of bushfires to suggest there is nothing unusual about this season. Experts disagree

Australia has suffered a devastating early bushfire season with fires across several states burning through hundreds of thousands of hectares and destroying hundreds of properties with the loss of six lives.

Australia Bushfires


New South Wales has been the most severely hit, with more than 1.65m hectares razed, an area significantly larger than suburban Sydney. All six deaths occurred in there and more than 600 homes were destroyed. At one point firefighters were battling a fire front about 6,000km long, equivalent to a return trip between Sydney and Perth.

In Queensland, 20 homes have been lost and about 180,000ha burned. In Victoria, where the bushfire season usually starts later, 100km/h winds fanned more than 60 blazes during an unprecedented heatwave on Thursday. The most extreme warning, a code red, was issued for the north-western and central regions. The state’s emergency services minister, Lisa Neville, compared it to “the worst conditions you’d see in February or March”.

Seven districts in South Australia were rated as being at catastrophic risk of fire on Wednesday as temperatures soared into the 40s. A blaze on the Yorke peninsula burned through about 5,000ha, damaging at least 11 properties and injuring 33 people. Western Australia has also experienced early bushfires in several regions, with fears of much worse to come over summer, and there were minor bushfires this week in Tasmania.



Is this unprecedented?

Australia has always had devastating bushfires, a point emphasised by some columnists and newspaper editorials, but scientists say the fire conditions this year are without parallel on several fronts.

Let’s start with the situation in NSW. Over the past 50 years, there have been just two calendar years in which more of the state has burned than this year: 1974 and 1984. With this year, those two were much larger than any other year, as this graph shows, based on data from the University of Wollongong’s centre for environmental risk management of bushfires:

NSW fires: total area burned
Showing the total area burned in hectares per year, with a year-to-date figure for 2019

Изображение

This year, which still has six weeks to run, sits fractionally behind 1984. Both are a long way behind 1974, when more than 3.5m hectares burned.

But scientists says fire conditions today are fundamentally different, and fundamentally worse in many ways, when compared with some of the fires experienced in the past.

The centre’s director, Ross Bradstock, says the 1974 fires burned through largely remote country mostly in the state’s far west, devouring green, non-woody herbaceous plants. The conditions were created by above average rainfall which produced ample fuel in outback grasslands.

By contrast, the fires in the east of the state this year have been fuelled by a lack of rain. The extent of the fires is in significant part driven by the amount of dry fuel available, some of it in highly unlikely places, and the amount of dry fuel is linked to the record-breaking drought.

Rainfall between January and August 2019 was the lowest on record in some areas, including the northern tablelands of NSW and Queensland’s southern downs. Parts of both states experienced record low soil moisture. As temperatures and wind speeds increased but humidity remained low, conditions were primed for small fires to become major conflagrations.

Drought in Australia: rainfall deficiency from January 2017 to August 2019

Изображение

Bradstock says it has put NSW in uncharted territory: “For the forests and woodlands in the eastern half of the state, this is unprecedented.

“Natural features in the landscape which often impede fires, like these wetter forest communities, are just burning. There is likely to be long-term ecological and other environmental consequences.”


The director of the fire centre at the University of Tasmania, David Bowman, says the unprecedented nature of the fires this spring can be seen through their intensity and geographical spread across the country, noting at time of writing there were fires in five states.

The extent of the bushfire risk is illustrated through Bureau of Meteorology data of the cumulative forest fire danger index across winter.

Winter bushfire weather conditions, 2019
Showing the cumulative forest fire danger index (FFDI) for winter (June to August) 2019 compared with all winters since 1950. The FFDI combines measurment of rainfall, evaporation, wind speed, temperature and humidity, and the cumulative FFDI is the sum of daily values over the specified period.

Изображение

The map shows the overwhelming majority of the country, with a few exceptions in Victoria, central Queensland and western Tasmania, experienced between “above average” and “highest on record” fire conditions in winter when compared with the average since 1950.

Bowman says the extraordinary nature of the fire season is clear on several measures: the extent of area burned, and the underlying dryness and poor air quality affecting people across the country. Smoke in NSW and Queensland has prompted a rise in people seeking emergency treatment for respiratory problems.

But as illustrative evidence he emphasises the areas affected in which fire has never or rarely burned in the past, including rainforests, wet eucalypt forests, dried-out swamps and organic matter in the soil where the water table has dropped.

He says one of the most striking images of the extreme fire conditions in recent weeks were those of a devastated banana plantation at Taylors Arm, west of Macksville, in northern NSW. He lists it alongside the loss of other landscapes – including Gondwana-era vegetation in the Tasmanian world heritage wilderness area that in some cases had not burned for more than 1,000 years – as evidence of change.

“There’s just layer upon layer upon layer of differences,” Bowman says. “If you narrow your frame you can say ‘nothing to see’. But if you broaden your aperture, it’s clear.

“I wrote a book on Australian rainforests. I’ve seen every Australian rainforest biome, and the fact that multiple versions of these ecosystems right around the country are burning all within the same couple of years … This is a really confronting warning light.”


What do other professionals dealing with fire say?
They largely back the scientists.

As has been widely reported, 23 former fire and emergency services chiefs from across the country have jointly warned climate crisis is making bushfires deadlier and the season longer, and called on the government to act.

Neil Bibby, former chief executive of Victoria’s Country Fire Authority and one of the 23, says:
“It has been the last couple of years where we have been realising things have started to change and this is the new future … It will only get worse.”


The chief executive of the Australasian Fire and Emergency Service Authorities Council, Stuart Ellis, says this bushfire season already has an “enduring nature”. “[It’s] just relentless,” he says.

Andrew Gissing, an emergency management expert at the Bushfire and Natural Hazards CRC and a consultant with Risk Frontiers, says an analysis of building losses from bushfire seasons back to 1925 suggests this season is already the third worst in NSW. In Queensland, about a third of all financial losses from burned buildings since 1925 have occurred this year.



Is this climate change in action?
No fire can be blamed on climate change alone, but Bowman says the rise in higher temperatures, extreme dryness, worsening fire seasons, extreme bursts of fire weather and behaviour and the spread of fire across the country all align with scenarios painted by climate change projections.

Greenhouse gas emissions have a clear impact on rising temperatures and, through that, an indirect link on increased dryness in eastern Australia. A recent study found the extreme temperatures that drove historic 2018 bushfires in northern Queensland were four times more likely to have happened because of human-caused climate change

In short - climate change can and does makes bushfires worse.

Bradstock says a range of published research has found escalating atmospheric concentrations of greenhouse gases are increasing the risk of the type of fires affecting NSW’s eastern forests, but reducing the likelihood of a similar fire to that experienced in 1974.

The elevated scores on the forest fire danger index in winter this year meant not only that the risk of bushfires was significantly heightened as the warmer seasons began, but opportunities for hazard reduction burning had been limited in some parts of the country – although NSW authorities still managed to meet its annual target of 135,000ha of prescribed burning.

Sarah Perkins-Kirkpatrick, from the University of New South Wales’ climate change research centre, says studies by the CSIRO and others have found the fire season has got longer, particularly in eastern Australia, where it is starting earlier. This is expected to continue until 2050 at least.

“We know that catastrophic conditions are now more likely to occur, and into spring as well,” she says.


On this year, Bradstock says: “I guess the most concerning thing to emphasise is it’s not over. We’re not even into summer yet.”

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