Australia’s leading climate scientists have urged the nation to brace for more extreme weather events as temperatures continue to trend upwards.
The country was devastated by , but scientists say most parts of the country should now be bracing for flooding over the coming months.
Delivering their sixth biennial State of the Climate report on Friday, researchers from the Bureau of Meteorology and CSIRO confirmed Australia's climate is continuing to heat up.
Australians told to brace for harsh weather conditions
The country's average temperatures have now increased by 1.44 degrees since 1910, and last year was the hottest year on record.
In Australia's already bushfire-prone southwest and southeast, conditions are getting drier, with rainfall in the cool season between April and October continuing to decline.
The Bureau of Meteorology's Climate Environmental Prediction Services manager Karl Braganza said that combination of heat and dry is the perfect recipe for worsening bushfire seasons.
“That shift in temperature and rainfall is partly driving a change in fire weather,” Dr Braganza said.
“What we can see in general is that, across Australia, particularly the southern parts, we have a longer fire season, there's more fire weather during that season, and the most extreme fire weather days are getting more extreme."
He said this pattern is most noticeable in the spring.
"We're seeing the fire season arrive months earlier in some instances in some southern parts of the country, which obviously reduces your fuel reduction period, but it also means that along with those early season heatwaves, we're seeing an earlier start to having fires in the landscape.”
These factors contributed to the devastating bushfires in Australia's south and southeast last summer, but Dr Braganza says most of the country will be at risk of flooding this summer instead.
Climate scientists say flooding will be the thing to watch out for over coming months. Source: AAP
“In contrast to the last few years, where we've had really severe and protracted droughts and natural drivers that have favoured drier more hotter conditions over summer and more fire weather, we've got a La Niña (effect) now in the Pacific,” he said.
Dr Braganza said La Niña events are typically associated with heavy rainfall and flooding across Australia.
"The last significant La Niña event in 2010-11 caused a record two-year rainfall total, widespread flooding across Australia and Cyclone Yasi," he said. "We also know that during La Niña, you tend to get slightly more tropical cyclones in the Australian region making landfall.
“So, fingers crossed this won't be as severe an event, but it really depends on how much sea surface temperatures warm up around Australia over spring. Those warm temperatures basically provide the moisture and the fuel for the weather systems that come over Australia.”
Climate scientists have urged the nation to brace for more extreme weather events as temperatures continue to trend upwards. Source: Bureau of Meteorology
How are ocean temperatures around Australia tracking?
The waters around the country have warmed by about one degree since 1910, and the frequency, intensity and duration of marine heatwaves are all increasing.
Australia's sea levels have also risen by 25 centimetres since 1880 - half of that since the 1970s - and are now expected to rise by another 3.5 centimetres per decade.
Research director of the CSIRO's Climate Science Centre Jaci Brown said rising sea levels can be attributed to two things: melting ice caps and thermal expansion.
“As the water warms, it expands, and that contributes to sea level rise,” Dr Brown said.
“The oceans take up around 90 per cent of the extra energy from climate change, and its one of the very clear signals we have around how climate change is happening for the globe.
“So, if you grab your ruler and head down to the beach, put your ruler at the edge of where you think the high tide is and have a look at what another 25 centimetres might mean, because 25 centimetres up can be a very long way in shore.
"And then, even more confronting - what would a metre of sea level rise look like?”
Oceans can also offer insight into how levels of atmospheric carbon dioxide are changing.
CO2 levels were once increasing by 10 parts per million per century - but Dr Brown said they've increased by 23 parts per million in the last decade alone.
“One question we get a lot here is 2020 was pretty tough with COVID-19, we saw a lot of companies closing down, people staying home - what did that do to the carbon dioxide signal?" Dr Brown said.
“Sadly, although carbon dioxide did slow down, we still saw an increase in the amount of carbon dioxide going into the atmosphere.
“This is about a very long-term change, and I think that the big challenge for our children and grandchildren will be how to flatten this curve.”
The next State of the Climate report is due to be released in 2022.
With additional reporting by Gavin Fernando.
