The Australia Bureau of Meteorology's heatwave service is working overtime as the country braces for temperatures of up to 47 degrees Celsius over the weekend. Preparation is key, so here's some practical tips on how to deal with the heat, from experts (and us).
— BOM Australia (@BOM_au) February 8, 2017
Where are we getting this information from?
The heatwave service shows a set of maps showing colour-coded heatwave severity for the previous two three-day periods, and the next five three-day periods. As part of the service, "assessment" maps show areas where heatwave conditions currently are, what they are expected to do in the near future, and if the intensity is severe or extreme status. This is the assessment as of today.
The heatwave forecast, on the other hand, gives us an indication of the next five three-day periods. It shows areas where heatwave conditions are forecast to occur and will also indicate whether their intensity is expected to reach severe or extreme status.
Three or more days of high maximum and minimum temperatures that are unusual for that location is considered a heatwave, and we know that one is on it's way when the forecast maximum and minimum temperatures over the next three days are compared to actual temperatures over the previous thirty days, then these same three days are compared to the 'normal' temperatures expected for that particular location.
The calculation takes into account people's ability to adapt to the heat. For example, the same high temperature will be felt differently by residents in Perth compared to those in Hobart, who are not used to the higher range of temperatures experienced in Perth.
This means that in any one location, temperatures that meet the criteria for a heatwave at the end of summer will generally be hotter, than the temperatures that meet the criteria for a heatwave at the beginning of summer.
The bulk of heatwaves at each location are of low intensity, with most people expected to have adequate capacity to cope with this level of heat. Less frequent, higher intensity heatwaves are classified as severe and will be challenging for some more vulnerable people, such as those over 65, pregnant women, babies and young children, and those with a chronic illness.
Even rarer and exceptionally intense heatwaves are classed as extreme, and will impact normally reliable infrastructure - such as power and transport. Extreme heatwaves are a risk for anyone who does not take precautions to keep cool, even those who are healthy. That's what we're bracing for here.
What does this mean?
Heatwaves have a range of economic and planning impacts across a broad range of sectors, including health care, transport, emergency services, energy and agriculture. Impacts to these sectors may also have an effect on responding to people in need. Knowing a heatwave is coming will help these sectors better prepare for these conditions, and reduce the level of impact to people, businesses and industry.
Government, emergency services and communities need time to adjust and to adopt measures to reduce the impact of a heatwave. Blackouts are more prevalent in severe and extreme heatwaves. Personally, we need to be prepared with an alternative source of power for radios and torches, and keep mobile phones fully charged where possible.
In the last 200 years, severe and extreme heatwaves have taken more lives than any other natural hazard in Australia. For example, during the 2009 Victorian bushfires, 173 people perished as a direct result of the fires; however 374 people lost their lives in the heatwave that occurred before the bushfires.
Violent weather events, such as tornadoes, floods, cyclones or severe thunderstorms tend to create a lot of media attention, including reporting on how many people lost their life or were injured. Heatwaves are not associated with these violent events, so tend to not be reported in the media to the same extent.
But heatwaves can result in significant health stress on vulnerable people. This stress may result in death during the heat event but in many cases this can occur well after the heatwave has passed. Often the cause of death during a heatwave is difficult to determine, as many people who die during a heatwave have a pre-existing or contributing health condition.
Unfortunately, climate projections show that extreme heat events are expected to occur more often and with greater intensity in the future.
Heatwaves are more complex than just the daily maximum temperature. The minimum (or overnight) temperature is extremely important as well. If the minimum remains high then the subsequent maximum will occur earlier in the day and remain near that high temperature for a longer period. A higher minimum temperature also restricts the amount of recovery that can occur, due to less opportunity to discharge heat.
So what do we do?
Associate Professor Ian Stewart is an environmental occupational and exercise physiologist who studies heat strain for at-risk workers in physically demanding jobs. His expertise has informed various temperature-related work regulations, and he has previously studied children's physical activities in the heat.
Dr Stewart says anyone working outside is at risk, but the more active their job is, the more they are at risk of heat exhaustion and heat stroke.
"Everyone generates extra heat internally which, under normal circumstances, dissipates into the cooler air outside the body, so that we maintain a core temperature of between 36c and 37c," Dr Stewart says. "But if the air outside is already 37c or higher, your body can no longer get rid of that excess heat – you've lost that natural mechanism for dispersing your internal heat. That's why heatwaves are a so dangerous."
And humidity brings added danger, he says. "It's double trouble when there is high humidity during a heatwave because your sweat is no longer doing its job. It pours off your skin before it has time to evaporate and cool you down."
"In a heat stroke situation, the body's cardiovascular system actually stops trying to send blood to the skin to disperse heat and starts concentrating solely on maintaining adequate blood pressure," Dr Stewart says.
"It's important to lie the person down, put ice packs under their knees and in their armpits and groin (where the main arteries are close to the surface) and give them small amounts of cool fluid (not ice-cold)."
Kelly Stewart, an accredited sports dietician, studies nutritional intake in athletes who are often working under extreme conditions. Ms Stewart says we also need to watch what we eat during a heatwave.
"Cold salads with lots of vegies and a protein-rich ingredient is a great choice in a heatwave," Ms Stewart say, "Try eating lots of cold fruits like watermelon or frozen grapes. Sandwiches with toppings that naturally contain a bit of salt will help you hang onto the water you drink."
Of course, we should also be drinking water - but not too much.
"Water, water and more water. A little bit of cordial is okay but not too much – we don't want to end the heatwave 5kg heavier," she says. "Active outside workers could benefit from a sports drink during the day to help them retain the fluid they're consuming but I'd advise a sports drink for children or the elderly only if they are dehydrated."
"Avoid hot meals altogether in a heatwave," Ms Stewart says. "Hot meals heat up your body as well as your house, neither of which you want to happen. Soft drinks or juice are generally unnecessary – a piece of fruit is a far better choice."
As for keeping your home cool, our friends at Lifehacker Australia have the best advice. Here's some of the main tips:
- Put a bowl of ice in front of your fan. If you're using a basic fan, this can greatly increase its effectiveness.
- Keep a spray bottle of water in the fridge. Spritzing yourself then provides a fast way to cool down. For maximum effectiveness, learn where your body's quick-cooling points are. For a portable variant, check out how to make a cooling scarf.
- Keep the curtains drawn. The effectiveness of this will vary depending on your kind of property, size of windows and orientation of the building. However, in many cases, keeping the sunlight out is more effective than opening the windows, especially on still days. You could also experiment with a green curtain of plants for even more cooling impact.
- Take advantage of public air conditioning. You don't have to stay at home: head to a shopping centre or a public library to take advantage of cooler temperatures.
- Don't obsessively keep track of the temperature. With everyone seemingly lugging smartphones, an update on the current temperature is only a glance away. However, knowing that it's 47 degrees won't help you, and could hinder you. Studies suggest that if we believe the temperature is lower than it actually is, we don't suffer from heat-related effects to the same extent.
- Make sure your computer isn't running hot. This won't massively change the temperature around the house (unless you have a very small office), but it's worth making sure your computer isn't running at excessive temperatures.
And of course, be sure to check on any elderly friends, family and neighbours - and don't leave pets outside or without a constant supply of water.
Stay safe, Australia.