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Geo Briefing: Australia’s bushfires

Geo Briefing: Australia’s bushfires Shutterstock
07 Jan
2015
Once again, the Australian summer is dominated by raging bushfires. Why is fire such a huge problem in Australia? 

As firefighters attempt to keep blazes under control near major cities in the southeast of the country, including a giant fire destroying homes near Adelaide, Australia is again dealing with the impact of immense bushfires. It is an ongoing problem, and one which can have devastating consequences; 173 people were killed by bushfires in Victoria in 2009, while major losses of life were caused by bushfires in 1983, 1969, 1968, 1967 and 1939.

But why is Australia such a tinderbox? What is it about the climatic conditions of the country which mean it is constantly on the edge of another huge fire?

1) Bushfires are always a threat

fire-seasonsImage: Australia’s Bureau of MeteorologyBushfires are a problem for Australia throughout the year, not just during the summer. High pressure systems across south Australia during winter can cause strong southeast to northeast winds, surging hot air from central Australia towards Darwin and surrounding towns, making them susceptible to fire. However, as most Australians live in the southeast – in or around the cities of Sydney, Adelaide and Melbourne – it is during this time of year, when grasses and forests have been dried out by the summer heat, that the largest and most destructive bushfires tend to strike. 

 

2) Australia gets very hot 

aus-max-temp-map-bom-14-1-14Image: Australia’s Bureau of Meteorology

During the peak of summer, around January, temperatures across Australia can reach well over 40oC, making conditions more and more suitable for fires to grow and spread. 2014 was officially Australia’s third hottest year since records began in 1910, according to the Bureau of Meteorology.

  

3) 2013 was especially hot 

20140103 daily tmean anomImage: Australia’s Bureau of Meteorology

Australia’s warmest year on record came in 2013. That September in particular had maximum temperatures of over 3.32oC above the 1961–1990 average. A September 2014 report by the American Meteorological Society concluded that it was ‘virtually impossible’ that these temperatures could have been reached without the impact of anthropological influences. In October 2013, the New South Wales region declared a state of emergency, as enormous bushfires in the Blue Mountains near Sydney destroyed hundreds of homes.

 

4) RAINFALL is low, sometimes non-existent

338miHrImage: Australia’s Bureau of Meteorology

Average annual rainfall for Australia is 465mm, with much of it concentrated in the north and southeast. The extremely dry conditions in central Australia make it very easy for fires to start. Also, rainfall is not always consistent; the Bureau of Meteorology described inland and southeastern Queensland, as well as northeastern New South Wales, as experiencing ‘prolonged rainfall deficiencies’ in 2014.

 

5) east australia is getting drier 

ausprecip1970-2011Image: Australia’s Bureau of Meteorology

The key to Australia’s bushfires is extremely dry grasses and forests, which can easily be ignited by anything from lightning strikes to accidental human activity. The trend of the past forty years is reducing rainfall across east and southeast Australia – the most populated parts of the country – making those areas more susceptible to bushfires. 

 

6) you can see bushfires from space 

nasaImage: NASA

This image, part of a night map of the whole world, was taken over three weeks in 2012 through a collaboration between the NASA Earth Observatory and the National Geophysical Data Centre. It appears to show the deserts of western Australia as inhabited by enough people to create more light than the country’s biggest cities around the coast. In fact, the satellite cameras are being tricked by a series of temporary bushfires which, when combined as a composite image, give the effect of a raging wildfire across Australia. Nevertheless, the fires themselves are genuine, even if they weren’t all occurring at the same time.

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