Sea salt particles preserved in the Law Dome core from East Antarctica were used to reconstruct bushfire weather patterns in southeast Australia over the past 2000 years.
"The ... records captured in Antarctica go much further back than our weather records in Australia," study lead author and University of Tasmania PhD graduate, Danielle Udy, said.
Scientists are studying ice core samples taken at Law Dome in Antarctica. (HANDOUT/AUSTRALIAN ANTARCTIC DIVISION)
Dr Udy said conditions during the 2019-20 Black Summer bushfires, which destroyed 3000 homes and killed 33 people, were unprecedented since records began in 1950.
However, observations of the ice revealed similar or worse bushfire weather had occurred before.
"At least seven times over the last 2000 years, bushfire weather in southeast Australia was as bad or worse than during ... Black Summer," Dr Udy said.
"These findings show natural climate variability can produce even more severe bushfire weather.
"On top of that, climate change is further adding to the intensity and frequency of severe bushfire weather.
"Buried in the ice is a warning: This isn't just a future risk. We need to plan for bushfire seasons worse than the Black Summer."
Weather systems that cause extreme bushfire conditions in Australia are so large they also impact Antarctica.
The "bridge" between the continents is preserved in the ice as changes in sea salt concentration, which scientists found decreased when bushfire conditions were worse in southeast Australia.
Anthony Kiem, associate professor and hydroclimatologist at the University of Newcastle, said the data was crucial.
"Our previous work has shown the roughly 120 years of rainfall observations we have do not fully cover the range of drought conditions ... in the past 2000 years," he said.
"Worse, our bushfire weather observations only extend back to 1950.
"Prior to this study we had limited insights into how bad bushfires can really be due to natural climate variability alone."
The research, published in scientific journal Communications Earth and Environment, involved several institutions including the Australian Research Council Centre of Excellence for Climate Extremes.
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