Gospers Mountain bushfire on December 21, showing the true colour image, and infrared imagery of the fires in yellow.

From above, Australia is a nation torched and scarred. Nowhere is this more evident than the eastern seaboard.

The yellow you see is infrared imagery that shows where the fires have been.

The charred landscape, now doused in torrential rain, is a reminder of the awesome power of fire, and the mammoth recovery task ahead.

The crisis has found a way to touch almost every Australian state and territory — a truly national emergency.

When our federal politicians left Canberra in December, the bush capital was untouched by fire.

Now they fly in over a blackened landscape.

Since July, the fires have burned through almost 16 million hectares in Queensland, NSW, Victoria, WA, SA, Tasmania and the ACT.

Conservative estimates put animal deaths at over 1 billion nationwide.

More than 3,500 homes have been destroyed.

And 33 people lost their lives. Among them, volunteer firefighters selflessly lending a hand.

So how did this happen?

A bushfire relies on four main factors to take hold: high temperatures, low humidity, strong winds, and a fuel source.

In early September 2019, in the Gold Coast hinterland, these four factors conspire to create a kind of bushfire rarely seen in Australia — a warning of what is in store for the rest of the country.

The southern half of Australia has just come off its driest January to August on record. Three years into a record drought, much of the country is bone-dry.

This is Lamington National Park in south-east Queensland as seen from one of the European Union's Copernicus Sentinel satellites. It is an outpost of an ancient rainforest surrounded by farmland 30 kilometres from the Gold Coast.

In 2016, the ridges of the area are tinged green.

But as several years of drought take their toll, the green recedes.

It creates the perfect conditions for a fire to take hold. All that is needed is a spark somewhere in the right place and the right weather conditions.

On September 2, a fire starts in difficult terrain at Sarabah. Higher-than-average temperatures, very low humidity and gusty winds lead to very dangerous fire conditions.

On September 6, the temperature hits 33.6 degrees Celsius. Strong and dry west-to-north-westerly winds send the fire through the wet sclerophyll, the eucalypt forest that grows on the boundaries of the sub-tropical rainforest near Binna Burra.

The yellow you're seeing among the smoke is infrared satellite data, which allows us to show the fire front.

The vegetation in this area is normally noted for its fire resistance, but conditions have caused the fire to take hold in an area where it normally wouldn't.

Days later the historic Binna Burra Lodge, a hub of eco-tourism opened 86 years ago, is taken by the fire.

The difference in the infrared imagery before and after the fire highlights the extent of the damage.

The fires burn through more than 3,600 hectares and continue to smoulder for months, re-igniting when temperatures push into the extremes, and each time pushing further into the rainforest. The area around the Binna Burra Lodge has never before burned in modern times.

By September 9, 80 fires burn across Queensland, and another 50 in New South Wales.

Forest Fire Danger Indices in south-east Queensland are around the highest they have ever been at that time of year.

Grant Williamson, a senior research fellow for the NSW Advanced Bushfire Research Hub, says the fires show just how dry conditions are.

"[In Queensland] we do have fires through the winter ... but the fact that these fires were severe enough to burn through rainforest really suggests a huge moisture deficit there," he says.

"The conditions were very dry and very hot, compared to what you'd expect."

Imagery from the Japanese Himawari weather satellite shows plumes of smoke clearly visible from space.

These are from vast fires burning through the forests of northern New South Wales.

"Once we started to see fires coming up in September through these parts of NSW it became clear to me that this was going to be a very long season."

Beneath the smoke are towns such as Nymboida, where close to 100 homes are lost when a wall of fire rips through the town.

More than 500 houses across the region are destroyed and four people are killed.

A confluence of climate events

Against the backdrop of record global warming, 2019 was a particularly bad year for bushfire weather.

Cooler waters off Western Australia combined with relatively warmer waters closer to Africa — a phenomenon known as a positive Indian Ocean Dipole — and resulted in less moisture in the atmosphere in the continent's north-west, changing the path of weather systems coming towards the country from the Indian Ocean.

The Australian Bureau of Meteorology says this phenomenon was long-lived, lasting from May until the end of the year. Lower than average rain during that period was the result.

Furthermore: "Spring brought an unusual breakdown of the southern polar vortex which allowed westerly winds to affect mainland Australia. This reduced rainfall, raising temperature and contributing to the increased fire risk."

It was amid these conditions that a bushfire, the size of which Australia had never seen, was sparked.

On October 26, a single lightning strike amongst dry tinder north-west of Sydney is the progenitor of Australia's largest recorded bushfire.

The blaze begins innocuously enough. Against the backdrop of a great number of fires at emergency level, it barely rates a mention at first.

But by mid-November, the fire has grown to 85,000 hectares and is poised to threaten properties.

Infrared imagery shows the scale of the expansion in less than a month.

The fast-expanding fire soon begins to blow smoke over the Sydney basin.

By December 16, the Gospers Mountain blaze joins with other nearby fires. Together, they have already burned through nearly half a million hectares, and would go on to burn close to 900,000.

On December 17, temperature records begin to tumble across the country. The average maximum temperature for Australia is 40.7C, surpassing the record of 40.3C set in January 2013, previously Australia's hottest year on record. Then on the 18th, the record is topped again, with 41.9C — more than a degree higher than the day before.

Satellite imagery from December 21 shows the scale of the blaze.

Sydney is ringed by the Gospers Mountain blaze, and to the south the Green Wattle Creek blaze, which is threatening properties and townships on the outskirts of the city.

The harbour city's backyard, which it has long been driving its fingers into in the quest for more land, has caught fire.

Dr Williamson says weather, topography and vegetation combined to allow the mega-fire to burn through such a vast area.

"We didn't have any significant rain events to slow it down, to put it out," he says.

"There aren't many breaks in terms of natural rivers, or roads or settlements, where the fire would naturally come to a stop, and be unable to spread.

"When you've got essentially a wilderness area with continuous vegetation going on for such a large area it's difficult to stop a fire. The length of the boundary you've got to fight it across just makes it very difficult to do."

Extreme heat

Amid the unfolding chaos, renowned US climatologist Michael Mann begins a family holiday in Australia ahead of a long-planned sabbatical in Sydney to study the very type of crisis he has just flown into.

Dr Mann was part of a group of scientists who were the first to show the drastic impact fossil fuels have had on global temperatures compared to historic records, and has been at the forefront of communicating the science of climate change for the past two decades.

"Given that I had planned my sabbatical more than a year ago — and the topic of my research was to be the impact of climate change in extreme weather events in Australia — it was rather surreal to arrive just in time to experience the most extreme example on record," he says.

On holiday in the Blue Mountains, sandwiched somewhere in between the two blazes, Dr Mann witnesses the devastating effects of the tragedy firsthand.

"I travelled with my family to see the Blue Mountains, only to arrive to see smoke-shrouded valleys and largely hidden cliffs and ridges."

Dr Mann is unequivocal about the cause of the tragedy: "Take record heat, combine it with unprecedented drought in already dry regions and you get unprecedented bushfires like the ones engulfing the Blue Mountains and spreading across the continent. It’s not complicated."

It's during these unprecedented conditions that two volunteer firefighters die when the cabin of their truck is crushed by a falling tree near Buxton, on the front line of the Green Wattle Creek fire.

Both men were fathers to young children.

Days later the fire tears through the regional town of Balmoral.

Twenty of the village's 120 homes are destroyed.

Under red skies

Christmas fails to bring respite, as the danger shifts to the south coast of NSW.

The area is dotted with towns set among eucalypt forests. Australians have holidayed here for generations.

Fires have been burning in the region around the town of Nowra since before Christmas, but the scorching temperatures supercharge the blaze.

The extreme heat from the fire front is clearly visible here in yellow and orange, as picked up by the Sentinel satellite's infrared sensors.

Further south, at 5:00am on New Year's Eve, an emergency warning is issued to residents of the small town of Cobargo.

Firefighters expect a southerly change to move the fireground north, and residents are advised to evacuate.

By 6:23am the fire is moving so fast that the Rural Fire Service is advising people in the town that it is too late to leave and to take shelter instead.

Satellite imagery from New Year's Eve shows thick smoke from infernos in Victoria's East Gippsland, burning since late November, blocking out the sky.

Underneath this smoke the bushfire is bearing down on Cobargo.

The tight-knit community of only 700 loses two of its members — a father and son defending their property. Many historic buildings on the main street are lost to the blaze.

Also beneath the plumes of smoke, the small holiday town of Mallacoota is under siege from the flames.

Thousands of people choose this spot to holiday during summer every year. But now the fire front has them trapped — there is no way out by road.

Sunrise on New Year's Eve brings an ominous, red glow; each photo emerging from the besieged town looks as if it is still developing in a darkroom.

The fire front pushes holiday-makers and residents onto the beach or the town's jetty — a small sliver of refuge against the blazes.

But even near the water, it isn't entirely safe. Evacuees are told they may need to get into the ocean to protect themselves if the fire gets too close.

A thousand people are eventually evacuated on Navy ships, with several hundred more leaving by air.

A new record for a new year

Early in the new year, the Bureau of Meteorology confirms what we all felt.

Not only was 2019 the hottest year on record for the country, 1.52C above average, but the nation also experienced its lowest rainfall since these two records began. December 2019 was a full 3.2C above average.

"Persistent drought and record temperatures were a major driver of the fire activity, and the context for 2019 lies in the past three years of drought," the bureau says.

Tom Beer is often referred to as the 'godfather' of bushfire and climate science in Australia. In 1988, he released the first research on the effects of climate change on bushfires in Australia.

While researching in 1987, when climate science was in its infancy, Dr Beer attempted to find a year where the temperature had varied more than 3.5 degrees above the average so that he could study what happened in that year as a model for the future. He was unable to find one.

"Even finding a year that was 1 degree warmer was impossible," he says.

And according to Dr Beer, the 2019 fires may already be the new normal, even if the world limits emissions under the Paris Agreement.

"Even limiting warming to 1.5 degrees under the Paris Agreement is more or less, in terms of bushfires, what you're seeing this year. If we get up to 3 degrees, then the fires are going to get worse."

Flames further west

The eastern states are not the only ones affected by blazes.

The same catastrophic temperatures in the lead-up to Christmas drive a blaze through the Adelaide Hills. More than 80 homes are destroyed, and one person is killed.

In the early days of the new year, the only sealed road between South Australia and Western Australia is closed for 12 days due to an out-of-control fire nearby.

And South Australia's Kangaroo Island, long a draw for holiday makers, becomes a microcosm for the situation facing the country, as soaring temperatures turbocharge fires that have been burning on the island since December.

Lightning sparks a number of fires on the island in mid-December; by New Year's Eve, two fires on the western end of the island are still burning out of control and threatening lives and property.

Two weeks later, the fires have laid waste to large swathes of the island's vegetation.

Around half of the island's area is touched by the inferno.

Two volunteer firefighters lose their lives …

As well as countless native animals which call the island home.

Summer, the time of year when we as a nation collectively agree to switch off, had turned on us.

The picturesque scenery which undoubtedly drew tourists to the area, now black.

A national crisis goes global

As the new decade dawns, the rest of the world watches on in horror as Australia burns. Images of the tragedy make front-page news around the globe, and we become the face of what a climate future could hold.

But it is more than just images that spread: plumes of smoke from the east coast crisis cross the Tasman in early January …

Turning the sky in Auckland orange …

And glaciers brown with ash.

While New Zealand had received ash and smoke from Australian bushfires before, Dr Williamson says the sheer quantity of this year's event was "probably unprecedented".

"[It's] a product of how much smoke there has been over such a long period that it's hanging around and able to travel a long way," he says.

"It's just indicative of the size of the event — it's quite rare."

In time the smoke circles the globe and then returns to Australian skies.

Mega blaze 2.0

As the season's first mega-blaze is brought under control, a second mega-blaze is already forming.

The Dunns Road and Adaminaby Complex fires in NSW combine with two other blazes straddling the Victorian border near Albury, forming a fireground that will eventually burn through more than 800,000 hectares.

Smoke from the fires settles over Canberra, trapped again by the surrounding mountainous terrain. Flights are cancelled, national museums temporarily shuttered.

Melbourne doesn't escape the haze either.

The mega-blaze and East Gippsland fires send their payload to our second-largest city, a poignant reminder of a still evolving threat.

The eyes of the world are on Australia once again as the city gears up for the Australian Open.

The poor air quality makes headlines around the world as players speak out about the conditions; some matches are cancelled or forfeited in the lead up to the tournament.

Five people were killed in the blazes in Victoria, and more than 400 homes were consumed by the flames.

From fire to flood

After an agonising wait, rain finally arrives, in the same fashion as all the weather this summer — with extreme, destructive force. A tropical low dumps record amounts of rain, extinguishing the fires and creating flash flooding.

Down the coast firegrounds are turned to flood zones and Sydney streets are inundated just weeks after they were wreathed in smoke.

Even this is an example of what climate change can look like. Because the atmosphere can hold more water in warmer temperatures, when it does rain we're seeing more high-intensity, extreme rain events — the ones that are associated with flash flooding. Every degree of warming creates a 7 per cent increase in the intensity of those rain events.

There's still more summer to run, which means the threat of national disasters looms large over the continent. And experts warn this threat will only increase as the world heats and Australia's climate warms.

Michael Mann says it will "only get worse" and result in "more extreme heat and drought, more destructive, faster-spreading bushfires, worse floods, more loss of life, more lost species".

He says that even a 1.5C rise in average world temperatures, as mandated under the Paris Agreement, leads to a scenario "in which Australians need to accept a new reality".

"Many fire-prone regions may become uninsurable, the first stage of uninhabitability. The cost of climate change is very real and we are already seeing it here."

Credits

Satellite Imagery