Australian heatwave – experts respond

The Australian Science Media Centre has collected extensive commentary from experts on a range of issues relating to the heatwave currently sweeping across the country.

Feel free to use these quotes below in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476;

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Climate change

Heatwave weather

Bushfire risk

Health impacts of heat


Effects on pets and livestock

Food safety in hot weather

Climate change

Dr Markus Donat is Postdoctoral Research Fellow at the Climate Change Research Centre, UNSW

“In recent studies we have analysed how extreme temperatures have changed globally. For most regions, including Australia, we found that extremely high temperatures have become more frequent and more intense, while extremely low temperatures are occurring less frequently than they did in the middle  of the 20th century.

“Counting the number of very warm days (in this specific case defined as the warmest 5% during the 1951-1980 period) we found that during the most recent 3 decades 1981-2010 the frequency of days in this warmest category has increased by 40% globally.”

Heatwave weather

Alasdair Hainsworth is Assistant Director Weather Service at the Bureau of Meteorology

“Extreme heat events, such as this one, have wide ranging impacts across agricultural and horticultural sectors, infrastructure and transport, and not least human health and safety.  Locations including Alice Springs, Adelaide, Renmark, Melbourne, Mildura, Echuca, Albury, Broken Hill and Wagga Wagga all have temperatures of 40 degrees or higher forecast for today.

“Another concern is the amount of vegetation following two wet years, which has led to high fuel loads, that continue to dry out and raise concerns about increased bushfire risk. Fast moving grassfires are of particular concern.

“Increasing fire danger is anticipated in southeast Australia with hot and gusty northerly winds, followed by a southwesterly change late on Friday.

“There will be some temporary relief from the heat on Saturday with this weak change, moving eastwards over the weekend.

“The next change is then expected to move through southern inland and coastal regions around Tuesday or Wednesday next week, but in other areas temperatures are expected to remain high, with a continuation of heatwave conditions well into next week.”

 John Nairn is South Australia’s Acting Regional Director for the Bureau of Meteorology

“Heatwaves are a normal part of Australian summers. Just like any other natural phenomena they exhibit variable intensity, although the time scales on which they vary can be very long. This multi-year variability makes it difficult for people to appreciate their exposure risk under this variability, leaving them vulnerable to severe and extreme events.

“Heatwaves become severe as the overnight minimum temperature rises.  A loss of lower recovery temperatures during heatwaves leads to an accumulation of heat in human and infrastructure systems, leading to failure amongst vulnerable communities of people or overstretched utilities.  An additional factor is the degree of acclimatisation or adjustment to rising thermal load which can compound the impact.  Over this summer, warmer than normal seasonal conditions leading into the current heatwave have reduced this factor, lowering the risk of an extreme event.

“The current heatwave is unusual due to its areal extent. More than 70% of the continent is currently experiencing heatwave conditions. Apart from the required slow moving synoptic weather pattern required for any heatwave, the spatial extent of this event can be attributed to the extent of dry soils across the Australian landscape.

“Low antecedent rainfalls across much of the continent (see figure) along with the late arrival of the Australian monsoon have resulted in drier soils.  Without the ability to remove latent heat through evaporation from moist soils, surface temperatures rise above normal, with the daily heating cycle building a deeper body of stagnating hot air over the interior.

“Breaking the heatwave cycle will require a combination of the onset of the rain bearing monsoon trough and the penetration of cooler Southern Ocean air masses.  Severe heatwave conditions across the interior of Australia are set to continue for a while yet.”

Bushfire risk

Dr Jason Sharples* is a Lecturer in Applied Mathematics at the University of New South Wales. He researches the processes that can result in the escalation of bushfires to their most destructive state.

“The risk posed by bushfires directly depends on temperature, relative humidity and wind speed, the level of moisture in forest soils and the curing state of grasslands.

“The current heatwave conditions in southeast Australia are associated with a trough of low pressure that is funnelling hot, dry air from inland Australia towards the coast. The resultant extreme high temperatures and low relative humidity causes vegetation to dry out more readily, so that combustion can proceed at a faster rate with a greater release of heat. This means that during the heatwave bushfires can be expected to spread more rapidly with greater intensity and flames that rise higher into the air.

“Heatwave conditions also increase the likelihood of large tracts of land burning simultaneously. This is known to be a precursor to the formation of firestorms such as those experienced in 2003 in Canberra and in 2009 in Victoria. In addition, the extreme heat lowers the amount of moisture in forest soils and exacerbates grassland curing, which both have the effect of increasing bushfire risk levels for the remainder of the fire season.

Gary Morgan is CEO of the Bushfire Cooperative Research Centre

“We have moved back into a normal summer of high temperatures, low humidity, and little rainfall, and the likelihood of many bushfires. We have already seen large fires across the top of Australia and through the Centre, and now the conditions are right for a southern bushfire summer. Our researchers have been closely watching the large areas of grass that have grown in the wet years right across the continent. Much of this grass has fully dried and is ready to burn.

“People need to plan, prepare, and act decisively when under threat of a bushfire. Our researchers spoke to many people after the big bushfires in recent years and disturbingly we found that although most people were aware that it was going to be a bad fire day, they thought it would be a bad day for someone else. We also found that many people adopted a “wait and see” approach – I will “wait and see” how the fire develops and then I will act decisively. With a fast moving bushfire or grassfire, this attitude can be fatal. We need to be realistic. On these extreme days, with high winds and potentially many fires going at any one time, our fire fighting resources will always be limited in what they can do. It is up to each individual to be prepared for bushfire and not solely rely on others.”

Dr Janet Stanley is Chief Research Officer at the Monash Sustainability Institute, Monash University

“Arson is Australia’s most costly crime, particularly bushfire arson. This cost includes loss of life, injury, psychological and social upheaval, personal financial loss, business and regional economic loss, damage to roads, schools and other infrastructure, environmental destruction which includes loss of species and biodiversity, and the massive release of greenhouse gases. It is suggested that, of the 60,000 fires which occur in Australia’s bush each year, one third to a half are deliberately lit. Some believe that this proportion is much higher.

“Little is known about arsonists, there is a low probability of apprehension and punishment of arsonists and a lack of suitable treatment programs. The gaps in our knowledge and our inadequate responses to bushfire arson are greatly out of proportion to its impacts.

“The substantial time and resources put into post-fire recovery would be much reduced if more attention and resources were devoted to prevention. Significant new thinking is needed around bushfire arson prevention, aimed at structural, service design and operational levels and supported by research and evaluation of impacts.”

A longer comment from Janet is available online here

Health impacts of heat

Professor Kevin Parton is Adjunct Professor at the Institute for Land, Water and Society, Charles Sturt University

“Adelaide: Our study shows that heat-related mortality and morbidity become apparent above maximum and minimum temperature thresholds of 30 °C and 16 °C for mortality; 26°C and 18°C for ambulance call-outs; and 34 °C and 22°C for heat-related emergency department presentations. A 10 °C increase in maximum temperature was associated with a 4.9% increase in daily ambulance call-outs and a 3.4% increase in mental health related hospital admissions for the all-age population. Heat related emergency department presentations increased over 6-fold per 10°C increase in maximum temperature. Public health interventions will be increasingly important to minimise the adverse health impacts of hot weather in Adelaide, particularly if the recent trend of rising average temperatures and more hot days continues as projected.”

“Perth: Our study shows that the temperature thresholds for mortality were estimated at 34-36°C (maximum) and 20°C (minimum). The health impact of heatwave days (three or more days of 35°C) was also investigated. A 9.8% increase in daily mortality was associated with a 10 °C increase in maximum temperature above threshold. Total emergency department presentations increased by 4.4% and renal-related emergency department presentations by 10.2% per 10 °C increase in maximum temperature. Heatwave days were associated with increases in daily mortality and emergency department presentations, while total hospital admissions were decreased on heatwave days. Public health interventions will be increasingly important to minimise the adverse health impacts of hot weather in Perth, particularly if the recent trend of rising average temperatures and more hot days continues as projected.”

Associate Professor Adrian Barnett is Principal Research Fellow, Queensland University of Technology

“Heatwaves in Australia and around the world have been associated with death and hospitalisation. However, it’s wrong to just focus on heatwaves, as days that are hot but not extremely hot also cause health problems. Hot temperatures trigger a range of physiological reactions including sweating and changes in heart rate and blood viscosity. These reactions can lead to heart attacks and respiratory collapse, particularly in those who are already struggling such as the elderly and those living with chronic respiratory or cardiovascular disease. On extreme heatwave days the number of people experiencing problems can be very high, creating a spike in ambulance call-outs and overcrowded hospital emergency departments. These spikes can be particularly bad if the heatwave is combined with a power cut, as this prevents people from using air conditioning, or a bushfire, as the combined challenges of heat and smoke can overwhelm the respiratory system.

“Heat is a particular concern for pregnant women, and our research in Brisbane shows an increased risk of stillbirth and preterm birth on hot days. Previous studies have shown the risks of saunas and heat packs, and pregnant women are advised to avoid these. Pregnant women may also need to avoid high outdoor temperatures.”

Dr Robert Grenfell is the Heart Foundation‘s National Director of Cardiovascular Health

“People most at risk are those with a chronic disease, such as heart disease, as well older people, children, people taking certain types of medicines, and people engaged in strenuous outdoor activity or physical labour. People who are in the high risk groups should take care during a heatwave and consult their GP about the best ways to manage their condition.

“Sweating leads to dehydration, which reduces the volume of blood. This makes the heart pump harder in order to circulate the reduced amount of blood around the body. For people with heart disease and those who are at high risk of a heart attack, these changes can overwhelm the heart and result in a heart attack.

“In Australia, heatwaves claim more lives than any other natural hazard.”

“People with a chronic disease such as heart disease need to take extra care during a heatwave, as studies have shown that people with heart disease and those who are taking medicines for blood pressure or excess fluid, such as diuretics, have a higher risk of falling ill, suffering a heart attackor even dying.

“A lot of the medications for heart patients work on the fluid levels in their body. During a heatwave people can suffer from dehydration which can compound the effects of medication and make people very ill. It’s still very important for heart disease patients to keep taking their medications. If they have concerns they should discuss their condition with their GP. “People should do their best to stay cool and drink plenty of water, but also need to be aware that fluid overload can make heart failure worse in some patients. People who are in the high risk groups should consult their GP about the best ways to manage their condition.

“This is only the start of a long hot summer so people need to prepare themselves and think about how they’ll manage.”

Tips during a heatwave:

  • Look after yourself and keep in touch with others
  • Drink plenty of water without waiting for thirst (if your doctor normally limits your fluids, check how much to drink during hot weather)
  • Keep cool – stay indoors or in an air-conditioned environment
  • Stay out of the sun
  • Reduce normal activity levels

Dr Margaret Loughnan is Research Fellow – School of Geography and Environmental Sciences, Monash University

“High risk groups include:

  • Older people (especially over 65 years) and babies.
  • People with chronic disease such as heart & circulatory disease, renal disease, endocrine disorders eg diabetes,  obesity, mobility disorders, dementia, respiratory disease.
  • People who live alone may be at higher risk as they can become dehydrated and disoriented with no-one there to notice and provide fluids.
  • People who speak language other than English may be unaware of heat warnings and miss advice provided by media in English only.

“Be aware of others in your community who may need assistance and check on friends, family and neighbours regularly.

“People should avoid exposure – stay indoors as much as possible.

“Use air-conditioners if available, and fans to circulate air.

“On hot days do essential jobs early before the hottest part of the day.

“Avoid cooking, eat small light meals.

“Avoid unnecessary activity.

“Drink plenty of fluids – at least one glass of water per hour, even if you don’t think you’re thirsty ( by the time you’re thirsty, you are already slightly dehydrated).

“Close windows and blinds/curtains early in the morning. Use a fan to move the air around. Place a bucket of water in front of the fan to circulate cool air as the water evaporates.

“Close doors and Cool one room – easier than the entire house.

“Place cool wet small towel around your neck. Use a spray bottle to mist skin.

“Wear loose fitting lightweight clothing.

“Take a cool shower and wet your hair.”

Debra Cerasa is Chief Executive Officer of MS Australia

“People with disabilities like Multiple Sclerosis (MS) can experience extreme relapses as a result of increase in temperatures. Symptoms such as the sudden loss of eyesight, the onset of chronic fatigue or walking difficulties can be brought on by as little as 1/2 degree rise in body temperature.

“We urge people with disabilities to take extra care during these conditions – keep as cool as you can and out of the sun.

Liz Hanna is Convenor, Climate Change Adaptation Research Network – Human Health, ANU

“Those of us who spend our days trawling – and contributing to – the scientific literature on climate change are becoming increasingly gloomy about the future of human civilisation. We are well past the time of niceties, of avoiding the dire nature of what is unfolding, and politely trying not to scare the public. The unparalleled setting of new heat extremes is forcing the continual upwards trending of warming predictions for the future, and the timescale is contracting. This trepidation on the part of scientist and researchers, and in some cases flagrant resistance by stakeholders in the fossil fuel industry, to allow the real story to be fully revealed and comprehended by the public at large, has allowed the stalling of action to save the planet, and ourselves.

“To speak of heat alone, heat already kills more Australians than the road toll. If it is not already double, it soon will be. From a health perspective, there is an upper limit to human tolerance of heat. We begin to feel ill when our body temperature reaches 38 degrees. Our metabolism and moving muscles generate heat which must be shed to the environment. This starts to become difficult when the air temperature exceeds 30 degrees, and is severely hampered as it reaches 35 or more. Most people cannot sustain physical exercise beyond a few minutes in very high temperatures without experiencing heat gain. It places great strain on the heart, and hence the elderly and heart conditions are particularly vulnerable.

“The temperature at which we succumb will vary according to the humidity; our familiarisation with hot conditions; our general capacity to thermoregulate (maintain our normal body temperature); our level of exposure to the heat, plus our level of heat generation via exercise. Physical exercise generates heat, and so our body tells us to slow down and rest. We feel lethargic. This is a survival mechanism, and should not be disregarded. Workplace and family duties that compel us to keep moving exacerbate our risk of overheating. We should not underestimate the seriousness of heat stress. Overheating can and does kill, even the young and fit. However, the most vulnerable to heat include the elderly, those with heart conditions, and the very young. People who cannot access cooled environments are also at risk. The response of turning on air conditioners only exacerbates the problem of global warming. The only correct response is to slow down, and ultimately reverse, the warming.”


Rachel Carter is Associate Lecturer and a PhD Candidate at the School of Law, La Trobe University

“People in Australia need to be mindful of what their insurance policy covers and if there are any exclusion clauses which are operational. This is critical even for people whose property is not in immediate danger.

“Lessons from Black Saturday and other events such as the Queensland floods show that often people are inadequately insured. The full extent of their underinsurance is often not realised until after a catastrophic event has taken place.

“Insurance is the only way under which individuals can have the economic protection they need to recover from catastrophic events.

“It is tempting for individuals to believe that fire will never affect them, but the reality is that fire is a real danger for many Australian households. So, it’s important to mitigate the risks through careful planning – both in terms of financial insurance and also to protect lives and property.

“When it comes to protecting life and property, people should ensure that the area around their properties is clear, gutters are kept clear and highly flammable materials are kept away from buildings throughout the bushfire season.

“People who vacate their properties during a period of high fire danger should ensure that pets and items of special importance, such as birth certificates, be taken with them.”

Effects on pets and livestock

Dr Rob Rahaley is South Australia’s Chief Veterinary Officer

“It sounds obvious but is nevertheless worth repeating: animals of all kinds need shade, wherever possible, to protect them from searing sun and wind. Also, they need good supplies of cool water; animals can drink up to double their normal intake during hot weather. Keep drinking troughs large and clean, especially when moving stock into a fresh paddock as evaporation may make trough water become saline and undrinkable. Feeder pipes should be buried to help temperature control and to prevent breakages. In hot weather, troughs should be inspected daily to ensure they are working correctly.

“Keep animals away from dams which may become boggy and a death trap for any stock seeking water. During hot weather, livestock should be checked daily to ensure they’re coping with the heat. Like humans, heat stress can be fatal for animals. The first signs of heat stress may include panting and drooling and stock may also be restless and start bellowing. Stock movements during hot weather should be minimised – both on-farm and off-farm. If there is no way of avoiding stock movements, then it should be carried out during night or maybe early morning, when it’s relatively cooler. Transporters of livestock should also have in place contingency plans to handle unexpected breakdowns, especially during hot weather. They must also be aware of new, national welfare laws governing the movement of livestock, information on which is available here.

“Poultry too are very susceptible to heat and if they’re kept in a shed that isn’t fitted with an effective cooling system, then the shed should be cooled by wetting the shed or hanging wet hessian in breezeways. Birds will need access to plenty of cool water. For pets, owners can use ice packs or wet towels to cool them down. Ensure pets have access to shade and water. Owners may consider bringing inside smaller pets, such as rabbits, during extreme conditions.”

Food safety in hot weather

The Food Safety Information Council is a non-profit entity supported by the Australian Department of Health and Ageing, state and territory health and food safety agencies, local government, and leading professional, industry and community organisations. They have issued the following tips to reduce your chance of getting food poisoning during the hot weather

“With every degree the temperature increases the risk of food poisoning also increases.

Your fridge

With the hot weather, check your fridge is running at 5°C or below – you may have set the temperature in the middle of winter and not touched the temperature dial since then.

If you don’t already have one, pick up a fridge thermometer from your local kitchen shop next time you are out.

Power failures

If the power fails make a note of the time the power went out.

If the power supply is out for more than 4 hours, food in fridges can spoil. Keep the refrigerator door closed as much as possible. A closed refrigerator should keep food cold for 4 hours. If food that’s meant to be in the fridge is allowed to warm for 2 hours or more, avoid eating it. Move food from the fridge to the freezer.

If available, put bagged ice under food packages and trays stored in freezers and fridges if power failure lasts more than 1 hour.

Place an insulating blanket over cold or frozen food where possible.

Freezers will usually not defrost and allow food to spoil for at least 24 hours, provided the door has been kept shut.

Try to keep cold and frozen food cold. If food is still cold to touch, less than 5°C, it is safe to use.

Once cold or frozen food is no longer cold to touch, 5°C or above, it can be kept, cooked thoroughly and eaten for up to 4 hours and then it must be thrown away or, if it is raw meat, it should be cooked and eaten.

If power is restored when frozen food is still solid the food is safe to refreeze.

Throw out food that was being cooked when the power failed if cooking cannot be completed properly within 2 hours. If food is already properly cooked, eat it within 2 hours or throw it out.

After a fire

One of the dangers of a fire can be toxic fumes from burning materials. Chemicals used to fight the fire can also contain toxic materials. The heat from a fire can cause bacteria in food to multiply and grow:

throw out any food that has been near a fire, including food in cans and jars even if it appears OK.

Any raw food, or food in packaging such as cardboard, plastic wrap, screw-topped jars and bottles should also be thrown out.

Throw out food from a refrigerator as the refrigerator seal isn’t airtight, fumes can get inside.

Wash cooking utensils exposed to fire-fighting chemicals in soapy hot water, then sanitise in one tablespoon of chlorine bleach per 2 litres of hot water and rinse.


If your water supply fails, use only bottled, boiled or treated water – in that order of preference – for drinking, cooking or preparing food, washing utensils and surfaces, brushing teeth, hand washing, making ice, and bathing.”