Professor Todd Lane - PURSUIT University of Melbourne
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Over the last few weeks, parts of Australia have been inundated by rain, scorched by heatwaves and slammed by storms.
Is this our country's new normal? how hot was it yesterday? Did those storms keep you awake? What’s happening with the fires? Have you seen how much rain is falling up North?
We all love to talk about the weather, and right now it is
the hot topic (excuse the pun) of conversation across much of
Australia.
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| A sweltering heatwave has breathed new life into existing bushfires in Victoria's west. Picture: AAP |
Is this the new normal?
We have always had extreme weather in Australia. But human-caused climate change is warming Australia and surrounding oceans at an unnatural pace, changing our weather patterns and modifying the structure and moisture content of the atmosphere.
These all ultimately lead to changes in the occurrence and intensity of many extreme weather events.
We can expect heatwaves to get hotter and longer, extreme rainfall from thunderstorms should get heavier and fire weather days are likely to increase in number.
These changes depend on location and scientists have more confidence in trends for some extremes compared to others. Nonetheless, there is high confidence that the ‘new normal’ is more extreme than the old one.
It is possible to determine whether a specific extreme event or group of events, like those many of us are experiencing now, are made more likely or more intense by climate change.
The process is called ‘event attribution’ and it typically requires detailed data analysis after the fact, a well-developed scientific understanding of the impact of climate change on extreme weather events and realistic simulation capability.
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| Large parts of the nation's north faced severe flooding, with some areas recording more than a metre of rain. Picture: AAP Image |
In 2023, a group of a group of Australia’s climate science experts (including myself) published a report on which extreme events could be robustly linked to climate change. We found that we can be most confident in statements connecting individual heatwaves and climate change.
Some of the more complicated or difficult-to-measure extreme events, like heavy rain and bushfires, can only be directly linked to global warming with low to medium confidence.
This means there’s still more research to be done to work out what the ‘new normal’ looks like, including how this might be different in a net zero world compared to one where net greenhouse gas emissions continue to increase.
The way most of the world will experience climate change is through changes in our weather. What we can say with confidence is that the new normal will feature high-impact weather events that test our resilience to climate change.
As these extremes play out, they highlight some of our future societal challenges.
In the coming years, we will break more heatwave records, especially in cities. Heatwaves kill more people in Australia than any other environmental hazard, and it’s our most vulnerable – the elderly and lower socioeconomic groups – that are most at risk.
Flash floods as a result of rainbursts will be more intense because the warmer atmosphere can hold more water. This damages our property and infrastructure, impacts agriculture and poses a risk to life.
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| Parts of Australia continue to experience heatwave conditions. Picture: Getty Images |
It is no accident that all these extremes are happening at once.
One of the wonders of the atmosphere is how simultaneous extreme events are connected by larger-scale weather systems.
The current high-pressure system in the Tasman Sea sets up the conditions that cause both the wet extremes in the north and the heat extremes in the south.
Fires and heatwaves also go hand-in-hand.
This tendency for extremes in Australia to occur at the same time – known as compound events – poses obvious additional challenges for emergency services and response networks who might already be stretched to their limits.
Unfortunately, our world continues to warm and extreme weather events will keep changing. This makes the concept of the ‘new normal’ poorly defined.
What is clear, however, is that society needs ongoing efforts to adapt to and mitigate the impacts of extremes like those we are now experiencing across the country.
These adaptations can range from policy changes, investments in more climate-resilient infrastructure, local community-based support and more. For example, the City of Melbourne supports community organisations to provide ‘Cool Places’ during extreme heat events to those most vulnerable.
At the same time, our ability to predict dangerous weather events is improving. Weather agencies use the latest supercomputing technology to forecast extremes more accurately and with more lead time than ever before.
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| This summer has seen Australia's Bureau of Meteorology issue several severe heatwave warnings. Picture: Getty Images |
This capability, which should continue to improve with ongoing investment in research and development, adds to our ability to prepare for extremes.
What is clear is that extremes will be part of our ‘new normal’, but that doesn’t mean we should feel resigned to this future.
As a planet, we still have the power to limit the occurrence and impact of future extremes through reductions in emissions and achieving net zero as quickly as possible.
Links
- Understanding climate change
- Attribution of extreme events to climate change in the Australian region – A review
- What does net zero emissions mean?
- do nothing’ approach won’t help Australia deal with bushfires as the climate gets hotter
- What will the America First Directive mean for international climate policy?
- Heatwaves and climate change are Australia’s deadliest ‘unnatural’ disaster
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