The two-yearly State of the Climate report, issued by the CSIRO and Bureau of Meteorology on Thursday, found global warming was bringing more extremely hot days and fewer extremely cool days to the nation.
Cool-season rainfall continued to decline across the country's south, while heavy rainfall bursts were becoming more intense.
Those short-lived rainfall events were associated with flash flooding, particularly in urban areas.
Flash flooding will be more frequent and harder to predict as temperatures continue to rise. (Dean Lewins/AAP PHOTOS)
The intensity of downpours had increased by around 10 per cent or more in some regions, particularly in the nation's north, bureau climate services national manager Karl Braganza said.
"That's associated with the increased moisture-holding capacity of the atmosphere," he said.
The oceans around Australia were also warming, contributing to longer and more frequent marine heatwaves and coral bleaching, and becoming more acidic.
Rates of sea level rise varied across the nation, with the largest increases in the north and southeast of the Australian continent.
After record-breaking heat in 2019, fewer temperature extremes had occurred in the past four years under La Nina conditions.
But extreme heat days in three of those four years were still high when compared with most years prior to 2000.
The rate of record-setting events in the climate system, both in Australia and globally, was really significant, Dr Braganza said.
Extremes such as record-low sea ice or record-high ocean temperatures globally were making forecasting weather and other impacts of climate change more difficult.
"Climate change and the rate of change in particular, is probably holding some surprises in terms of the impacts that it has across Australia," Dr Braganza said.
The report said the "primary and unequivocal driver" was the atmospheric accumulation of greenhouse gases including carbon dioxide and methane.
Australia is not reducing carbon emissions fast enough to counteract the impacts of climate change. (Dan Himbrechts/AAP PHOTOS)
Australia has reduced its emissions since 2005, but curbing emissions must accelerate to meet the nation's 2030 targets.
The vast majority of Australia's carbon emissions in the past decade have come from coal, oil and gas, averaging 399 million tons of CO2-equivalent per year.
Fossil fuel exports have contributed another 1055 million tons annually.
Natural land and ecosystems on average offset about half of Australia's domestic annual emissions.
Global emissions continued to grow and the world could only afford another seven years like 2023 to give itself an odds-on chance of limiting warming to 1.5C, the report found.
Another 15 years like 2023 would likely push temperatures past 1.7C.
"This is a global question and all of the world needs to be taking this seriously," CSIRO climate research manager Jaclyn Brown said.
"It's going to be tough to stop warming at 1.5 degrees."
Skyrocketing insurance premiums will determine housing affordability for future generations. (Dean Lewins/AAP PHOTOS)
Warming would have far-reaching implications, including in the financial services industry, which has been hiking insurance premiums to account for increasing disasters.
Housing affordability for the next generation would become less about the price tag but rather if they could afford insurance, Dr Brown said.
Climate Change Minister Chris Bowen said the report reiterated the urgent need to act on climate change and the government had a credible plan that would "reap the economic opportunities of the clean energy transformation".
The federal opposition has pledged to build seven nuclear plants across five states if they win government in 2025.
But questions remain over whether the plan relies on keeping ageing coal-fired power stations in operation into the 2040s.
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