Australia's hottest year on record will be mild by comparison if the country's emissions continue to rise at the current rate, experts have warned.
Representatives from Australia's national science agencies appeared before the Royal Commission into National Natural Disaster Arrangements on Monday to lay out the role climate change played in past and future disasters, in the wake of the devastating Black Summer bushfires.
CSIRO Chief Research Scientist Dr Helen Cleugh said the conditions Australia was experiencing were "within the projected range" of predictions the agency made in the early 90s.
She warned if greenhouse gas emissions continued on their current trajectory, the temperatures experienced in 2019 would be considered a "cool" year by 2050.
2019 was both the hottest and driest year on record, with 43 extreme heat days compared with the previous recordholder, 2013, where there was 27.
Even if emissions were lowered, 2019 temperatures would be considered an "average temperature year", Dr Cleugh said.
Ocean levels would also continue to rise, as Australia and the rest of the world were "partially locked in by our past emissions".
"As we look further into the later century and to centuries beyond that, beyond 2100, those sea levels projections critically depend on the greenhouse gas emissions from now onwards," Dr Cleugh said.
Her evidence came as Bureau of Meteorology's head of climate monitoring Dr Karl Braganza warned Australia's naturally variable climate was being exacerbated by climate change.
Australia's temperatures had warmed by about 1.5 degrees over the last 100 years.
The fire season now started three months earlier than in the 1950s.
Winter and spring rainfall - while highly variable - was also in a long-term decline, and expected to fall further.
"We can see that now in the increased frequency of large scale heatwaves and record high temperatures and a longer fire season with more extreme fire days," he said.
During December, most of the country was experiencing above average to highest on record fire danger days, according to the Forest Fire Danger Index.
However the situation could have been worse.
Dr Braganza said many areas which were in the highest danger zones did not ignite, such as the Otway Ranges in Victoria
"Could conditions have been worse over summer? Certainly they could have if we had more ignition in these orange zones," Dr Braganza said.
The conditions would have also been worse if there was an El Nino event occuring at the same time, which is normally associated with severe fires but was absent this time, Dr Braganza said.
Dr Braganza said this was not a one-off event.
"Really since the Canberra 2003 fires every jurisdiction in Australia has seen seen some really significant fire events that have challenged what we do to respond to them and have really challenged what we thought fire weather looked like," Dr Braganza said.
The events were also becoming more frequent, he said.
"These large fire events, when you look back over the 20th and 19th century were not as frequent as they were this century," Dr Braganza said.
The commission was set up amid a political firestorm over the federal government's handing of the 2019-20 bushfires.
It received around 1700 submissions and will hear from 50 witnesses over the next two weeks.
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