Australians will need to batten down the hatches with more intense rain storms predicted as a result of higher humidity driven by a rise in global temperatures.
New findings from the ARC Centre of Excellence for Climate System Science, published in Nature Climate Change on Tuesday, reveal that a two-degree rise in average global temperatures would lead to a 10-30 per cent increase in extreme downpours.
The study's authors predict that while some parts of the continent will become wetter, others will experience increasing drought.
Steve Sherwood, a professor at the Climate Change Research Centre at the University of NSW who contributed to the research, said global warming would have a clear impact on rainfall.
"There is no chance that rainfall in Australia will remain the same as the climate warms," he said.
"With two degrees of global warming, Australia is stuck with either more aridity, much heavier extreme rains, or some combination of the two."
The findings come as Sydney prepares for two days of above average temperatures with a maximum of 31 degrees forecast for Tuesday and 36 degrees forecast for Wednesday. The Bureau of Meteorology is forecasting rain towards the end of the week.
The scientists examined the heaviest rainstorms across Australia, focusing on the different climates of Sydney, Melbourne and Darwin.
They found greater average humidity led to an increase in heavy downpours. Even in areas where humidity and rainfall was lower, a two degree increase in global temperature led to an 11 per cent increase in total rainfall.
The study's lead author Jiawei Bao said most parts of Australia would be affected by an increase in global temperatures.
"Extreme precipitation is projected to increase almost everywhere in Australia from tropical regions in the north to mid-latitudes in the south and from dry deserts in the centre to wet places along the coast," he said.
"Rising air temperature is the primary reason for this change. Australia's infrastructure will need to be prepared to adapt to these more extreme rainfall events even if we act to moderate the global temperature rise to within two degrees."
Australia is a signatory to the 2015 Paris Agreement, a global aim to keep average temperature increases to well below two degrees.
Professor Sherwood warned that current policies worldwide are not enough to meet the Paris targets.
The study found that a four per cent rise in global temperature, possible based on current increases in the rate of carbon emissions, would lead to a 22-60 per cent increase in extreme rain storms.
"It is likely we face even greater changes unless policies are strengthened," Professor Sherwood said. "Australia can not use past observations alone to develop rainfall infrastructure. This research tells us we need to be prepared to adapt to a world of far more intense rainfall extremes, if we can."
