"I think the size and intensity of these fires, along with the drought, have just pushed Australia to a place that no longer feels like home." said Linden Ashcroft, professor of climate science and scientific communication at the School of Earth Sciences at the University of Melbourne. "It doesn't seem safe anymore."
A dry bush waiting for a spark
Australia is getting hotter and drier for decades.
This never happened before.
Without the rains, the dry bush provided the fuel for this year's fires. All that was needed was the spark.
"The signs are that this will become more common. We had a perfect storm of events this year. But I don't think it's an exaggeration to imagine that this is how our summers will be in the future, which is really quite conflicting," said Ashcroft.
Land of extremes
In addition, Australia is known for extreme fluctuations in the climate. In the summer, it is not uncommon for cities to see 40 ° C one day and heavy hail rains the next day.
But the climate crisis is making these fluctuations worse, experts say.
"What we are seeing now is that natural variability is occurring beyond human-induced climate change in the long run, and that we are seeing extremes becoming even more extreme," said Nerilie Abram, a professor from Australia. Research School at the University of Earth Sciences in Melbourne.
Boosting Australia's uneven climate, there are several climate systems that have conspired in such a way this year to exacerbate hot and dry conditions.
The IOD describes changes in sea surface temperatures between the opposite eastern (near Indonesia) and western (near Africa) parts of the Indian Ocean, and has three phases: neutral, positive and negative.
A positive IOD – which is what we have seen in recent months – is a sustained warming of the waters near the Horn of Africa, while the water in northwest Australia becomes extraordinarily cold. This cuts off one of Australia's main sources of moisture, leading to less rainfall and higher than normal temperatures.
Another climate system called Southern Ring Mode (SAM) also contributed to Australia's dry weather conditions this year. SAM is the movement of a strip of westerly winds that are pushed north, towards Australia, or south, towards Antarctica, and its impact in Australia differs depending on the season.
There has been a long-term tendency for SAM to become more positive, said Abram, meaning that the westerly winds between Australia and Antarctica are shifting further south. As a consequence, the parts of southern Australia that receive winter rain from these winds are not receiving as much.
But SAM went through a negative phase between late October and late December – the beginning of Australia's summer – shifting the west wind belt over the Southern Ocean towards the north towards the equator, fanning the flames of the fires. forestry.
"These climatic factors acted not only to increase fire hazards, but also to suppress the thunderstorm activity that we normally expect to impact parts of eastern Australia during spring and summer," said Diana Eadie, a meteorologist at the Australian Extreme Weather Desk Bureau of Meteorology.
Scientists say the rise in greenhouse gas emissions is distorting natural climate factors.
Since the 1960s, positive dipole events in the Indian Ocean have become more common and stronger, according to Abram, and climate models suggest that the trend is likely to continue.
"If we continue on a path of high emission of greenhouse gases, we expect these events to be three times more frequent in the 21st century compared to the 20th century because of human-induced climate change," she said.
This is the proof
Abram, one of the signatories to the letter, said it was "disheartening", as a climate scientist, to have made predictions correctly for years and that governments ignored them.
"This is what climate change looks like – it's really here now, it's affecting us now. And it's going to get worse unless we drastically reduce greenhouse gas emissions," added Abram.
Along with the increased risk of fire, more intense droughts, heat waves, prolonged summers and less rain are reserved for Australia if the world does not limit warming to 1.5 ° C above pre-industrial levels, according to the Paris Agreement. Currently, global C02 emissions can heat the Earth by 3 ° C or more by the end of the century.
Questions are being asked about how this warmer future would impact water resources, livelihoods, business, tourism and even the ability to live in certain parts of the country.
"There probably needs to be some discussion about where it is safe to live or where it is safe to build," said Ashcroft. "(But) I don't think Australia will reach a point where it will be a kind of Mad Max anarchy. I believe we have the ability to adapt and change what we do."
Australia needs to take a two-pronged approach to survive in the coming decades, experts say: Adapt to global warming temperatures and mitigate them and their effects. Moving away from fossil fuel energy sources will be critical.
What is needed now, said Abram, is real leadership.
"Because what we're talking about is not just a little bit of adjustment in terms of our savings," she said. "We are talking about the need for a managed transition in the way we operate."
CNN's Jessie Yeung and Angus Watson contributed to the report.