EXPERT REACTION: Widespread flooding across the eastern states

Although the impacts of this very severe weather and climate event have been devastating for many, as a meteorologist and climate scientist for 50 years I’m so proud of my young colleagues (especially those in the Bureau of Meteorology) who have been so effective in producing and disseminating accurate and precise climate and weather forecasts. Without their astounding efforts, the devastation (and loss of life) would have been so much more severe.

These efforts have included warnings that the La Niña would increase the likelihood of heavy rains, through to the detailed forecasts of the current weather event several days ahead (and then from hour-to-hour). Radar loops on the Bureau’s web pages has also allowed people to make short-term decisions based on when the worst storms would hit. The recognition that the greenhouse effect is increasing the intensity of heavy rains has also alerted people to the dangers of our current weather and climate situation.

As floods impact Victoria and New South Wales, it is important to provide immediate relief to affected communities and reconsider the ways in which disaster mitigation has been conducted in the past.

According to the United Nations Office for Disaster risk reduction, storms and floods are some of the most common types of disaster globally. International examples show that it is key that communities are involved in the reconstruction process and in the long term plans for climate change adaptation.

The case of the Flemington racecourse in Melbourne highlights the importance of involving local residents in the debates about climate resilience and adaptation.

The racecourse, located in a historic floodplain, received flood walls in the early 2000s to ensure that it would be protected from rising waters. Residents of Maribyrnong have raised concerns as the wall has altered the local water flows and might be aggravating the current floods in the area. 

Our research points to important strategies that can be used to create platforms for collaboration between local communities and decision makers. These collaborations are essential to allow for residents to voice their concerns and influence disaster risk reduction strategies. 

This collaboration can happen through mobile applications, social media or research projects using community-based approaches, such as citizen science and participatory mapping, which draw on local flood knowledge and collaborative action. 

The significant rain event and flooding over eastern Australia in the last 24 hours was related to a complex low and frontal weather system passing over the region. High rainfall totals through central Victoria and northern Tasmania dumped over a month's worth of rainfall in 24 hours in some locations. The flooding in these areas is a result of persistent wet conditions associated with an ongoing La Niña event, leading to sodden landscapes, which mean that significant rain events, not necessarily unusual in of themselves, can easily lead to flooding. The Bureau of Meteorology has been forecasting a wet spring, which we are now seeing come to fruition. The wet conditions related to the La Niña are likely to continue until at least the end of the year. 

The current floods should not be a surprise, the Bureau of Meteorology warned last month of possible above average rainfall this spring and summer due to the effects of La Niña. There were also warnings in the recent days of this impending event.

So what is more important to consider and assess at this stage is how prepared agencies and communities are to deal with and manage the floods. Questions such as how effective are the evacuations; what response and recovery plans are in place; and importantly, what specific attention and provisions are made for high-risk and vulnerable groups such as the elderly, children, First Nations people and people with disabilities.

This is a time for assessment and taking stock of what lessons have been gained from the previous recent floods and how they are being translated in the current flood context.

Natural disasters like floods are bad news for mums and their babies. Prenatal stress is associated with poorer birth outcomes and poorer develop across childhood. But negative consequences are not inevitable. Here are 5 ways we can make a difference:

1. Don't skip meals or prenatal multivitamins and keep diet quality high. Volunteers, family and friends can help with this.
2. See the same midwife through pregnancy, labour and postpartum. Health systems can implement midwifery group care models in disaster affected areas.
3. Focus on emotional availability during early childhood, using sensitivity and structuring to encourage bonding and development. Support to mothers could provide info on these strategies. Families and friends could help with other tasks so mothers have the time and head space to focus on this kind of parenting.
4. Match your coping strategy to the situation. Emotion-focused strategies like social support, reframing and humour can help during the flood once you're somewhere safe. Problem-focused strategies can help after the flood has receded when it's time for planning and practical support. Communities can help with active coping, like flood clean-ups.
5. Screening for mental health issues during pregnancy and throughout the early postnatal period should focus on depression and anxiety but also PTSD, with a focus on detecting and treating symptoms as early as possible. Health systems can prioritise screening in affected communities.

With attention, planning and care we can make a difference after natural disasters.

The rainfall and flooding is consistent with our understanding of how a La Niña event impacts our region. Other climate drivers, such as a positive Southern Annular Mode (SAM) and negative Indian Ocean Dipole (IOD) have also aligned to favour above average rainfall for eastern Australia.

The above average rainfall for spring was well-forecast by the Bureau of Meteorology and seasonal climate prediction models a number of months in advance. This is despite the La Niña being a rare third event in a row. Improving our climate models and predictions further will help support our ability to plan for and cope with events like these in the future."

Extreme weather events, such as the heavy rainfall battering the eastern states, can be likened to a military conflict. How enemy forces behave during a conflict depends on many decision makers: generals, lieutenants, all the way down to individual soldiers. Similarly, extreme rainfall occurs through the culmination of physical processes from the planetary scale, down to the microscopic. Yearly/planetary scale processes like the Southern Annular Mode and La Nina are like the generals: over the last year they have ordered warmer than usual waters, and more easterly than normal winds around the eastern states, producing a moister atmosphere.

Daily/state scale processes, like the Rossby Wave high/low pressure patterns on the evening news, are like the lieutenants: they organise this moisture, and decide the particular day, and the particular eastern Australian states, to attack. Hourly/suburb scale processes, like thunderstorms, are like the individual soldiers: they decide the particular suburb and time of day to attack. A strategic defence requires understanding and anticipating how the enemy, from generals down to individual soldiers, will behave, and launching our own response across these scales.

Wetter than normal condition has persisted over Eastern Australia, with heavy rainfall and flooding occurring in some areas. The persistent wet condition is a signature of a La Nina which has occurred subsequently since 2020. In addition, a negative Indian Ocean Dipole (IOD) event is currently active.  A negative IOD tends to see higher than normal rainfall over southeastern Australia, such as Victoria. Extreme rainfall generating weather systems, which can occur at any times, can lead to flooding especially given the already wet condition and saturated catchments.  

The La Nina event is currently expected to weaken in summer. A negative IOD does not typically last beyond spring. Another factor is the Southern Annular Mode (SAM). The SAM has been in a positive phase and is expected to continue in the coming weeks. The SAM is not very predictable beyond weeks. Stay updated with weather forecast, be alert and stay safe.  

Even as the rest of the eastern seaboard has faced the brunt of three consecutive La Niña years, Victoria has had little flooding until now. Tasmania, too, is facing rare flooding, while flood-weary New South Wales is bracing for more.

These heavy rains are unusual. Dense cloud bands have crossed the desert, carrying moisture evaporating from seas off north-west Australia. Rain has fallen across almost the entire continent in the last two weeks. Our rain events are usually regional – not national.

 Victoria is more familiar with flash floods. That’s because the stormwater drains in cities and towns can be overwhelmed by sudden dumps of rain, flooding streets. The good news is this flooding is usually over quickly, in contrast to the flooded rivers we see up north.

This situation may be different. With the state’s major dams beyond capacity or very close to it, water is already spilling over. Dams in Australia are often dual-purpose, storing drinking water and allowing us some control over floods. While Brisbane’s dams are designed with gates to permit floodwater release, Victoria’s dams tend to just have dam walls.

Australia experiences big swings between droughts and floods and many in the southeast are feeling the effects of extreme rainfall at the moment. Unfortunately, with our third La Niña in full swing and wet conditions likely to persist for at least the remainder of spring, flooding is more likely than normal. La Niña increases the chance of more widespread rain events across Australia and higher rain totals in the east and north. An early 2023 weakening of La Niña is forecast but predicting when these events finish is challenging so Australians should prepare for wet conditions to continue.

The current negative phase of the Indian Ocean Dipole has been responsible for a series of frontal systems since late winter. When they reach southeast Australia the rain bands intensify due to favourable upper level conditions in combination with a blocking high pressure area south of New Zealand. A lot of the rain falls on the inland side of the ranges in both NSW and Victoria. Such regularly occurring inland rain bands are a recipe for widespread flooding especially when catchments are saturated.

Furthermore, when the upper level system reaches eastern NSW, low pressure has been developing at the surface over the Tasman Sea, often providing short duration heavy rain and seen in bands that continuously affect the same NSW coastal strip of land. These coastal rain bands seen on weather radar can be quite narrow but the Tasman Sea provides a readily available moisture source for the rain.

If the current situation in the eastern states isn’t a sure sign we need to reconsider where and how our houses are built, then there’s a long and volatile road ahead for Australian housing.

The majority of existing and new housing in Australia is not suitable for performing in our current climate.

Predicted climate changes over the coming decades will only exacerbate this issue for many Australian households. We are already seeing the negative impact on people's health and wellbeing during extreme weather events. In some cases, households will find their housing unliveable for periods of time if we see climate change much further.

Before buying an existing house, people should seek out information about the quality and performance of the house. Home energy assessments, such as the Scorecard, can provide households with the likely performance of the dwelling as well as some key opportunities for improving performance through cost-efficient retrofit.

New housing standards will increase in 2023 but while this will make housing more resilient to a changing climate, there is more that should be done to future-proof new housing moving forward.

The Australian housing market is already experiencing its most volatile period since the beginning of this century, primarily due to the emergence of new drivers in the housing market due to the natural and man-made disasters.

About one in 25 Australian homes are at high risk of becoming effectively uninsurable by 2030, according to a new Climate Council report based on analysis by a climate risk assessment group (ABC, 2022).

With the insurance companies already imposing higher insurance premiums (or not insuring at all) and the banks getting more reluctant to lend on flood-prone or cyclone-prone locations, it is reasonable to conclude that flood-prone properties will be facing significant downward pressure due to rising sea level and as such, will under-perform other residential property types into the future.

This flooding has exposed something we already knew, but had chosen to ignore. That Australia, one of the most prone countries to secondary disasters from climate change, like flood and bushfire, is also one of the most under-insured of comparable economies.

Many Australians are uninsured or underinsured for flood because each time it floods, their premiums go up. At a certain level that becomes unaffordable so they take the risk of going without insurance. That’s not a risk that they as individuals can afford. Each time an uninsured property floods, society has to pay to help those people make good. At the same time, the wealth and viability of those owners to contribute economically to society is reduced.

There are very sound reasons to start pooling these risks across society - and using the data developed in the pool, to inform better disaster resilience of properties. There are other models worldwide we can learn from about successful risk pooling and resilience. We need to act now.

The problem is that legacy issues when we had drought led to intense development on floodplains. We also had weaker laws. 
 
Now we have legal awareness a of climate change as a risk and legal duties evolving at the domestic and of course international level. This will place an extraordinary burden on society to make hard decisions to stop exposing emergency workers and vulnerable community members to risk.
 
Our federation allows several localised standards to exist and these do not work and possibly infringe human rights to equity in development.