Thursday, January 31, 2013

Bushfires in Australia, Wildfires in America

Australia’s heat wave has caused temperatures to soar and the risk of bushfires to increase dramatically ( Bushfires surged through New South Wales and Tasmania in recent days, destroying properties and forcing many people to flee their homes. The fires are fuelled by the soaring temperatures of the heat wave as well as powerfulwinds. Hundreds of firefighters have been battling the blazes across Australia, which have been fanned by winds over 70 km/h (~44 miles/h).

Monday 7 January saw a nationwide average maximum temperature of 40.3°C (104.5°F), setting a new record for Australia's hottest day on record and beating the previous record of 40.2°C set on 21 December 1972. The national maximum temperature had also averaged above 39°C (102.2°F) for six consecutive days. There is a ‘dome of heat’ over the centre-east of the continent, and the Australian Bureau of Meteorology has had to extend its temperature scale to include temperatures up to 54°C (129.4°F; Australia is 7,618,000 km²; for comparison, here is a visual of the size of Australia compared to North America:

Firefighters in NSW (New South Wales) have been battling 135 blazes in temperatures above 40°C and a fast-moving fire in Victoria has destroyed two properties. 40 fires in NSW remain uncontained but fortunately there were no reports of loss of life or homes; the fires have burned more than 26,000 hectares (~65,000 acres) of grass, scrub and bushland. Up to 90 percent of NSW was in severe danger and a total fire ban is in place and there is a total fire ban in place in ACT (Australian Capital Territory) as well. The fire in Victoria was about 500 hectares in size (~1235 acres) and created spot fires one kilometre ahead.

In Tasmania, communities that are in the path of a destructive bushfire in the state's southeast have been told it was too late for people to leave. The Tasmania Fire Service (TFS) has advised people that they should head to the Eaglehawk Neck jetty or beach. More than 100 properties have been destroyed in the state already. About 110,000 hectares (~271,000 acres) have now burnt out across the state.

Australia’s vegetation has evolved with fire and has characteristics that promote the spread of fire. Eucalypt is coarse and decays slowly; the bark of many other species is flammable; and green leaves contain highly flammable oils and resins that promote combustion. When weather patterns occur that enable hot and dry winds to blow from the centre of the continent combine with previous drought, bushfires are sparked.

It is not just Australia that is affected by increasing temperatures. 2012 was the hottest year on record for the USA. The average temperature of 13°C (55.3°F) was about half a degree warmer than the 12.4°C (54.32°F) reading in 1998 and the 12.39°C (54.31°F) average in 2006. The temperature went above normal every month from June of 2011 to September of 2012, which had never been seen before in 118 years of record-keeping. Around 100 million Americans experienced 10 or more days of temperatures exceeding ~38°C (100°F). Among the cities experiencing their hottest years on record were Chicago, New York, Boston, Washington, D.C., Milwaukee, St. Louis, Denver and Des Moines.

August 2012 saw many large fires spark across the western and central U.S. regions as they experienced dryness, low humidity, and windy conditions. This resulted in a year-to-date average fire size of 70 ha (173.5 acres), the most since 2000. August’s total of ~1.5 million ha (3.64 million acres) burned by wildfires was the highest for any August since 2000.

While Australian bushfires and American wildfires require hot and dry conditions with preceding drought, American wildfires are triggered by lightning strikes and thunderstorms in some areas. Another cause is the build-up of grass, leaves and twigs in a pile: this collection of dead matter can create enough heat at times to spontaneously combust and ignite the surrounding area.

Unfortunately Australia is likely to be at risk of further bushfires and record-breaking heat in the future due to climate change. There is also likely to be an increase in fire risk across the U.S. by 2050. ‘‘Clearly, the climate system is responding to the background warming trend. Everything that happens in the climate system now is taking place on a planet which is a degree hotter than it used to be’’ Australian Bureau of Meteorology’s manager of climate monitoring and prediction, David Jones, said. Record-breaking heat will become more and more common. Though there is some natural variation, there are many more hot records than there are cold records.

The image show flames from the Deans Gap bushfire glow through the smoke covering Princes Highway at Shoalhaven on the NSW south coast on January 8, 2013.

Australian resources:

American resources:

Image courtesy

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