Fires and floods: Australia already seesaws between climate extremes – and there is more to come | Neville Nicholls | Opinion
”Unprecedented” is the word that keeps being tied to the apocalyptic weather Australia has faced over the past few months.
Bushfires have always been a reality in Australia, but never recorded on this scale with such widespread damage. It’s estimated that more than 60,000 sq km have been scorched in New South Wales and Victoria alone. Days of smoke have shrouded Sydney, Canberra and Melbourne. And after the fires, flooding at the weekend in NSW and parts of Queensland left thousands without power and dozens of schools closed on Monday.
While the country is still grappling with the economic reality and human devastation caused by the fires, it’s easy to think the worst of this disaster is over. But unfortunately other extreme weather may yet occur this summer and these will also require safety preparations and rapid responses.
Last year was the driest and hottest year on record in Australia. Some parts of the country have had several years of drought in a row. But all droughts end eventually. At the weekend devastating storms swept through eastern NSW, causing flooding, power outages and commuter chaos. The Bureau of Meteorology says 391.6mm of rain fell over Sydney in the past four days, the most since 414.2mm fell from 2 to 5 February 1990.
Historically Australian continental-scale droughts are often broken by widespread heavy rain, leading to an increased risk of flooding, including potentially lethal flash floods. The flood risk from the heavy rains is exacerbated by the bare soil and lack of vegetation caused by the drought and by bushfires that destroy forest and grassland. When a decade-long drought ended in 2009, what followed were two extremely wet years with serious flooding. Flooding also brings the risk that ash might contaminate water supplies. The heavy rain falling on bare soil can also lead to serious erosion.
The onset of the tropical wet season over northern Australia has been very much delayed, as predicted in the middle of last year by the Bureau of Meteorology. Most of the Australian tropics have had well below average rainfall in the past few months, and some areas had their lowest November-January rainfall. As well, the tropical cyclone season was late, also predicted by the bureau months ago. In recent weeks there has been some cyclone activity and some rain. But the wait is still on for widespread tropical rains and for more cyclones to cross the coast as Damien did at the weekend. Although rain brought by cyclones are often welcome, these systems can also leave serious damage.
We are at the riskiest time for heatwaves in southern Australia. The risk usually peaks around the middle to the end of summer. Weather conducive to increased bushfire risk also usually peaks in February for southern states. So although media, community and political attention have focused on the horrendous bushfires we have already suffered, we should not overlook the likelihood of other extreme weather, including cyclones, floods and heatwaves, or think that the bushfire risk is over for the year. It is important to remain vigilant for all weather extremes.
Avoiding ‘forecasting fatigue’
Although the fires have tragically claimed many lives, many others have been saved by the improved firefighting and warning systems, supported by improved weather and climate forecast systems to emergency services and the media by the Bureau of Meteorology.
Temperature forecasts five days ahead are better than one-day-ahead forecasts were 50 years ago. Rainfall forecasts have also improved dramatically. As well, scientific seasonal climate forecasts of rain, drought and seasonal cyclones – something not even dreamed of 50 years ago – are provided routinely by the bureau. These longer forecasts allowed emergency services to better prepare for this horrible summer, and the detailed shorter-range forecasts of weather conducive to fire spread has helped fire agencies target warnings and provide resources to threatened areas.
But one challenge as the summer continues will be the need for continued communication between forecasters, emergency services and the public about predicted extreme weather. For some, “warning fatigue” may set in and announcements of dangerous heatwaves or floods might be ignored. The warnings must continue to be disseminated to at-risk populations and local authorities must strive to ensure they are acted on. And meteorologists must keep up their efforts to improve forecasts on all timescales.
Tackling the bigger, global issue
Global warming is already lengthening the fire season and making heatwaves more intense, more frequent, and longer. It is also increasing the likelihood of heavy rains and flash floods while simultaneously making droughts worse in some areas. The occurrence of devastating bushfires has been increasing in the past few decades, despite better forecasts and improved firefighting technology and organisation. The intrinsic link between these weather extremes and climate change means we need to address the wider issue: what can we do to slow the rate of global warming.
Australians pride themselves on winning against the odds and adapting to extreme weather. How often have you heard a politician say Australia has always been a land of droughts and flooding rains, or that we have always had heatwaves and bushfires? Australian rainfall is indeed more variable than most parts of the world, so the reality is that we do face extreme weather, year after year.
But another reality is that daytime temperatures across Australia have increased by more than a degree just in the past 25 years. In the 1990s on average about 5% of the country each year had annual average daytime temperatures in the hottest 10% of historical temperatures. But over the past five years, on average, more than half the country has experienced such hot temperatures each year. From 5% to over 50% in the lifetime of generation Z. Such strong warming must affect not just all the weather extremes – droughts, floods, heatwaves, bushfires, cyclones and storms – but also their impacts on humans, animals and the bush.
And there is no reason to expect this warming to slow without concerted political action. So we need an increased focus on how to deal with these amplified risks from climate and weather extremes – how to adapt – at the same time that our politicians lead global action to slow the rate of warming. We don’t have much time. We need to adapt, to manage the unavoidable, and slow greenhouse gas emissions to avoid the unmanageable.
• Neville Nicholls is an emeritus professor at Monash University. He spent 35 years with the Bureau of Meteorology, with his research focusing on how and why the climate is changing