Weather forecast? Getting hotter, says State of the Climate report

More extreme heat events, a drier south and a wetter north, drier streams, a longer fire season, fewer tropical cyclones and less snow.

All of these trends have been recorded in Australia over the past half-century; all are projected to get worse from global warming.

That’s the bleak, but unsurprising, conclusion of the 2024 State of the Climate, released today by the CSIRO and the Australian Bureau of Meteorology (BOM).

“What’s already happening is going to be exacerbated into the future,” says report co-author Dr Jaclyn Brown, Climate Research Manager at CSIRO.

The CSIRO and the BOM have been producing State of the Climate reports every 2 years since 2010. The reports draw on long-term monitoring from both agencies, aiming to provide information on how Australian weather and climate is changing.

Like the 2022 report, and those before it, the study finds that the Australian climate is continuing to warm; extreme weather events are becoming more common; and sea levels are continuing to rise.

“These human-caused changes to the weather have far-reaching impacts on society,” says Dr Kimberley Reid, a climate scientist at the University of Melbourne, who was not involved with the report.

“Australia is causing these impacts by continuing to burn coal, oil, and gas, and by exporting vast quantities of fossil fuels to be burned overseas.

“If we continue to burn fossil fuels at home and export them to be burned elsewhere, we will continue to increase Australia’s risk to severe weather events.”

The report finds that, at current greenhouse gas emission rates, the global carbon budget for 1.5°C of total warming will be exceeded in 7 years.

This means that, to have a 50% chance of keeping global temperatures within the bounds of the Paris Agreement, rapid and deep emissions cuts are needed now.

The 1.7°C budget will be exceeded in 15 years at current emissions rates.

“It’s sobering, and it’s a tough one – 7 years for the whole globe to turn around,” says Brown.

“If we do go past that, there is still hope to then bring it back to 1.5°C but that’s a lot harder once the greenhouse gasses are out there, and some of the effects won’t be reversible.”

Pacific nations, Brown stresses, need the world to remain within 1.5°C to prevent sea level rise from threatening them with total inundation.

By the numbers: State of the Climate report

• Australia’s climate is 1.51°C hotter than in 1910 (when national records started), give or take 0.23°C
• Sea surface temperatures are 1.08°C hotter than in 1900
• 8 of the 9 hottest years on record have occurred since 2013
• Winter rainfall has decreased by 16% in southwest Australia and 9% in southeast Australia since 1994
• Wet season rainfall has increased by 20% in northern Australia since 1994
• More than 28% of stream gauges have seen a significant decrease in flow since 1970, while 4% have recorded a significant increase – decreases are mostly in the south, while increases have been in the north
• Global sea levels have risen by 22cm since 1900, with more than half of the rise happening since 1970

For more on what these numbers mean, read our explainer.

Changes in the land

“The climate of the 1980s and the 1990s is very different to the climate that we’re experiencing today,” says report co-author Dr Karl Braganza, manager of climate monitoring at the BOM.

Not all of the changes are consistent around the country or over the whole year. For instance, April-October rainfall has dropped in southern Australia, while October-April rainfall has increased in the north.

But others – like the frequency of extreme heat events and heatwaves – are happening everywhere, at all times of year.

“We know that heatwaves are becoming longer, the central intensity is increasing, and they’re becoming more frequent,” says Braganza.

Fire weather happens more frequently, and over a longer span of the year.

“There’s been an increase in extreme fire weather in most of the fire-prone parts of the country,” says Braganza.

“That’s a longer fire season, most notably pushing into spring. We are now starting to see fires almost every year occur in late winter and early spring.”

Tropical cyclones, meanwhile, are becoming less frequent – but those that do occur are becoming more intense. Short-duration heavy rainfall events are becoming more frequent.

These extreme events will become more costly as the climate warms.

“We are paying a heavy price, with the annual cost of property damage from extreme events now roughly double what it was only five years ago,” says Professor Ian Lowe, from Griffith University, who also was not involved with the report.

“My kids always say, ‘Oh, how will we ever afford a house?’” says Brown.

“It’s not, I don’t think, whether they can afford to buy a house. For a lot of people, it’ll be whether they can afford to insure it.”

Changes in the ocean

“The ocean really is a big part of the story of climate change,” says Brown.

“The ocean really helps us to its own detriment by taking up about 90% of the energy [of global warming]. Seawater holds about 4 times the amount of heat at the atmosphere.

“So we’re seeing the ocean warm, not just at the surface, but right down deep as well throughout the globe. And that changes the patterns of how the ocean currents work.”

This ocean heating is causing changes in the weather, as well as sea level rise from both thermal expansion and melting ice caps.

Sea level rise isn’t uniform: northern and southeastern Australia have recorded the biggest increases.

“It doesn’t just go up like a bathtub – there’s a lot of other factors in what happens with sea level,” says Brown.

Ocean currents, and wide-scale phenomena like El Niño and La Niña, play a big role in local sea levels, as does the buoyancy of the land.

“Sea levels can also rise where the ocean is warming the most – we’re seeing that down near Tasmania,” says Brown.

Time for emissions cuts

“Sometimes when I go home at night, I wonder what it’s like to not have a job like this,” says Braganza. “Sometimes, I also think that maybe my job isn’t so difficult. I’m a bit like a doctor, and I just have to say: ‘Hey, this is what’s going on’.”

This is because “the science is really clear”, says Braganza.

“You need to get to net zero as quickly as possible. That’s a little bit like telling someone who’s got a large drinking habit or smoking habit, ‘you need to quit that as soon as possible’.

“Obviously, making that change is really hard. It can’t just happen overnight.”

According to the report, fossil fuel burning, extraction, and land-based carbon sinks meant that Australia contributed a net total of 200 million tonnes of CO₂ into the atmosphere each year from 2010-19.

“Given the situation, it is grossly irresponsible for governments to continue to encourage and subsidise new fossil fuel projects,” says Lowe.

“It is an urgent priority to supplement the good work being done to decarbonise our electricity supply with a moratorium on new fossil fuel projects.

“The need for rapid change reinforces the obvious conclusion that we need urgently to invest in solar and wind energy with storage.”

The report authors say that awareness is an important way for Australians to help mitigate the problem.

“Most important, I think, is education, that this is real and this is happening, and putting in  adaptation measures,” says Brown.

“In your house, in the way you get to work – what is that going to look like in hotter conditions? What will happen with increased rainfall and flood events on your house? Is it ready to withstand that?”

“[I’d] really encourage people to work out through their networks in terms of that awareness, and to look at what they can influence that’s in front of them,” says Braganza.