Australia is experiencing one of its worst fire seasons ever. Since September, 15.6 million acres of Australia have burned. That’s an area larger than the Provinces of Nova Scotia and Prince Edward Island combined. The fires have now killed at least 25 people and destroyed almost 2,000 homes. More than a billion animals are thought to have been killed according to a prominent scientist whose new estimate is more than double what he predicted just weeks ago.

Chris Dickman, a professor of ecology at the University of Sydney, has revised his estimate of 480 million animals affected by the fires. On Wednesday Dickman said that more than 800 million animals have likely been killed in the Australian state of New South Wales alone. That means the number of animals affected nationally likely exceeds –unimaginably – 1 billion.

The blazes turned skies orange and made breathing the air in Sydney as bad as smoking 37 cigarettes. Those are just the impacts to people. The destruction to the country’s land and biodiversity is harder to fathom.

Scientists fear long-term damage to many sensitive ecosystems.

Though rain brought firefighters a slight reprieve Wednesday, the AP reports that hot and windy conditions that will keep the fires burning are expected to return later this week.

It’s a disaster that’s particularly ominous: In a warming world, extreme fire events like this one will only grow more likely to occur.

Nearly 100 Canadian fire experts have been sent to Australia to help battle the wildfires

Foreign Affairs Minister Francois-Philippe Champagne says Canada has offered to help Australia further if they ask for it – including by providing financial support – but a spokesman from his office says all Australia has requested so far is more people.

The Australian national council for fire and emergencies says 97 Canadians have deployed to Australia to help this season.

Most of the Canadians are there to help with aviation, logistics and prevention, while Australia relies heavily on local volunteer firefighters to battle the blazes.

One group of Canadians arrived to cheers and applause as they pushed through the doors into the airport arrivals area in Sydney on Jan. 6.

Widespread drought and multiple heat waves are creating perfect conditions for fires, which have scorched millions of hectares of bushland.