A booklet for Students and the Community
Chapter 4
Heatwave
Hazards and Disasters
THE MAJOR THREAT TO LIVES
In Australia during the 20th Century, heatwaves have caused more deaths than any other natural hazard (except disease), yet they remain one of the least-studied and most-underrated. In many other countries too, they are the major natural killer. Official death tolls in heatwaves everywhere tend to be well-understated. Many heat-related deaths go unreported because they are often assumed to be the result of an existing ailment.
DEFINING A HEATWAVE
A heatwave is a complex phenomenon resulting from a certain combination of temperature, humidity, air movement and duration. Simply stated, a heatwave is an extended period of very high summer temperatures with the potential to adversely affect communities.
HEATWAVE DANGERS AND EFFECTS
Heat Stress
Human Effects - In many parts of the world, every summer tens of thousands of people suffer from heat stress when their bodies absorb more heat than they can dispel. Unless prompt treatment is received, they suffer the serious or even fatal consequences of heat stroke (hyperthermia). Usually it is the cumulative effect of dwellings heating up for days on end, without the relief of cool nights, which results in widespread heat exhaustion and many deaths. At most risk are: very young children; the elderly; people with weight, chronic ailments or other health problems; and those on medications or with alcohol/drug dependency - all of which have a drying effect or reduce perspiration - the body’s cooling system. Very poor and homeless people are often victims as they cannot always seek the safety of a cooled home.
Agriculture - In
the same way that heatwaves affect humans, animals may suffer too, particularly when left
without shade and adequate water. Therefore,
during heatwaves, especially in times of drought, stock losses can be very high. Cases of tens of thousands of deaths among battery
hens are not uncommon in Australia. Plants,
crops and vegetables are also subject to damage and loss from the effects of severe heat. For example, in January 1990, at Mildura in SA,
grapevine damage alone cost $16 million (1997 values) on a day when the temperature
reached 47°C.
Vegetation - Heatwaves also take their toll on plants and trees. In Australia, exotics and species from cooler regions are generally the first to suffer. When searing winds blow with temperatures around 40°C, such plants often perish. When temperatures exceed 40°C for days at a time, even native species can suffer, particularly if they are not receiving regular moisture. These conditions are, of course, ideal for severe bushfires, to which heatwaves are usually a major contributor. For example, the 1997 Dandenongs bushfires in Victoria broke out during 41°C heat, and on ‘Ash Wednesday’ in February 1983, temperatures exceeded 43°C in Victoria and SA.
Overheating and Excessive Consumption
Infrastructure - During heatwaves railway lines can expand to the point where they buckle and cause derailments of trains. Road damage can also occur with bitumen melting and concrete expanding and cracking. Even bridges have suffered. The old Gladesville Bridge over Sydney Harbour, on several very hot occasions during the 1960s, expanded so much when it was opened for ships that it could not be closed again, causing traffic chaos.
Utilities and Services - Water consumption increases dramatically during heatwaves, often causing shortages, while water supply failure has even resulted on some occasions. Increased use of fans and air-conditioners causes increased demands on electricity and some appliances overheat, fail and sometimes cause fires. During a 7-day heatwave in SA in February 1997, hospital computers and bank auto-tellers overheated and failed in Adelaide.
HEATWAVE - COMPARATIVE CASE STUDIES
As suggested above, heatwave is a very underrated hazard, and no less here, than in the USA, as the following case studies show:
1.
History of Heatwaves in the USA
Many older Americans remember the smothering heat of the 1930s, when drought and numerous long heatwaves created what was known as the ‘Dust Bowl’ decade. It destroyed farms throughout the mid-west states, driving farmers from their land and killing nearly 15,000 people in 10 years. Sudden, violent disasters like cyclones and bushfires focus public attention while tortuous heatwaves can affect much larger areas, often leaving a greater, but more scattered, toll. It was in 1900 when a hurricane killed 6,000 in Galveston, Texas, an event often ranked as America’s worst natural disaster. Yet the very next year, in July, a heatwave in the mid-west ultimately cost 9,508 lives. Similarly, Los Angeles region heatwaves resulted in 546 deaths in 1939, 946 in 1955 and 580 again in 1963. Thus, each of these little-remembered events killed more people than the very famous San Francisco earthquake and fire of 1906, which took 452 lives.
2.
Australian Heatwave History
Also in Australia, great heatwaves such as the one in 1896 which
killed 437, were less-reported and sooner-forgotten than events like Cyclone Mahina whose
death toll of 410 in 1899 has not been exceeded by another cyclone since. Even the 1939, ‘Black Friday’ bushfires,
which swept Victoria killing 71 people, are far more easily recalled than the accompanying
heatwave which claimed 438 lives and directly contributed to the holocaust of that fateful
January. A much more recent example of how
the effects of heatwaves are under-rated, occurred in January 1994. While all national media concentrated attention on
the NSW bushfires which caused a total of 4 deaths, in the Townsville region of
Queensland, 5 heatwave deaths went almost unnoticed, except for the local newspaper.
Australia-USA Comparison - It is interesting to compare (on a per capita basis) the death tolls of our worst heatwaves with the August 1995 heatwave in the USA which caused about 800 deaths (from 240 million people). It is obvious that the Australian events (over 430 deaths each) were vastly more significant for our small population of well under 10 million in 1939, and far fewer in 1896. Many other high death tolls resulted from early Australian heatwaves as recorded in the disaster statistics table in Annex A.
HEATWAVE PROTECTION AND SURVIVAL
Although the effects of heatwaves can be so serious, they are one of the easier hazards to protect against if you are in good health. However, if global warming increases, heatwaves will become hotter, longer and even more frequent, so it is important to be aware of how to cope and survive:
Wear lightweight, light-coloured, loose, porous clothes and a wide-brimmed hat.
Avoid direct sunlight if possible. Use strong sun screen, as sunburn limits the body’s ability to cope with heat.
Do not leave children (or pets) in parked vehicles. Give animals access to shade and water.
If you have a baby or children under 4 years, pay particular attention to the above advice and consult a doctor if they appear uncomfortable. If you are elderly or suffer from a chronic condition, illness, or just feel unwell, see a doctor immediately.
Avoid strenuous activities and drink two to three litres of water per day, even if you are not thirsty. Do not consume alcohol or carbonated drinks.
Avoid heavy protein foods (eg meat, dairy products, etc) which raise body heat and increase fluid loss. Do not take salt tablets unless prescribed by a doctor.
Keep your home cooler with curtains, shutters or awnings on the sunny sides and leave windows open at night.
If you don’t have air-conditioning, use fans and damp towels etc to stay cool and have frequent cool showers. During the day spend as much time as possible in air-conditioned buildings (eg shopping centres, galleries, museums, etc).
Check on elderly neighbours and relatives to ensure they are comfortable and coping.
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EMERGENCY MANAGEMENT AUSTRALIA, PO
Box 1020 Dickson, Australian Capital Territory 2602, AUSTRALIA Telephone: + 61 (0) 2 6266 5402 Facsimile: +61 (0) 2 6266 5029 Email: ema@ema.gov.au AUSTRALIAN EMERGENCY MANAGEMENT INSTITUTE,
Mount Macedon Road, Mount Macedon, Victoria 3441, AUSTRALIA |
| This page was last updated May 31, 2001 |
