More than 1 billion animals are now thought to have been killed by the record-breaking wildfires in Australia, according to a prominent scientist whose new estimate is more than double what he predicted mere weeks ago.

Chris Dickman, a professor of ecology at the University of Sydney, revised his estimate of 480 million animals affected by the fires, saying Wednesday 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 1 billion, he added.

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The updated figure includes animals killed directly by the fires and those that have already died by indirect causes, such as starvation, dehydration or habitat loss. The estimate includes mammals, birds and reptiles, but does not include frogs, insects and other invertebrates.

“What we’re seeing are the effects of climate change,” Dickman said in a statement. “Sometimes, it’s said that Australia is the canary in the coal mine with the effects of climate change being seen here most severely and earliest … We’re probably looking at what climate change may look like for other parts of the world in the first stages in Australia at the moment.”

Dickman’s estimate is based on landmark research on animal density for a 2007 World Wildlife Fund-Australia report. That study examined the impact of deforestation and land-clearing on Australian wildlife and found that these practices are taking a serious toll on the country’s mammal, bird and reptile populations.

More than 32,000 square miles of land have been scorched by the fires, and more than 120 blazes are still active across New South Wales and its neighboring state of Victoria. Though rain brought some much-needed relief early this week, forecasts are calling for dry conditions and higher temperatures Thursday, which could increase the fire risk in these states.

Australia is home to a rich diversity of animals, including 300 species native to the continent. Scientists are concerned that the wildfires may wipe out entire species, or alter some ecosystems permanently.

Approximately 34 species and subspecies of native Australian mammals have become extinct within the last 200 years — the highest extinction rate of any region in the world, according to the University of Sydney.