Geoscience Reference
In-Depth Information
30
25
20
15
10
5
0
-5
-10
-15
-20
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Year
Figure 3.3 Frequency of record high and low minimum temperatures in Australia,
1910-2011
Source: Trewin and Smalley, 2013
Notes
a Black bars represent high temperature maxima.
b Grey bars represent low temperature maxima.
c Data are taken from a fixed and well-spread observational network. Records refer not
to progressive record setting (as a function of time) but records broken relative to the
entire distribution of events. Yearly counts represent the number of monthly station
records broken across the network in a calendar year.
Fire weather
Many parts of Australia are prone to large bushfires. Southern and eastern
Australia are particularly vulnerable to both forest and grassland fires occurring
in close proximity to populated centres. For example, in Canberra, fires in
January 2003 killed 4 people and destroyed 500 homes. In Victoria, fires in early
February 2009 killed 173 people and more than a million animals, and around
430,000 hectares of land were burnt, destroying more than 2,000 homes and
costing about $4.4 billion (Victorian Bushfires Royal Commission, 2010).
In most Australian states, fire weather risk is quantified using one of two
indices: the Forest Fire Danger Index (FFDI) or the Grassland Fire Danger Index
(GFDI) (Luke and McArthur 1978). The Fire Danger Rating system is used
by fire agencies to reflect the fire behaviour and the difficulty of controlling a
particular fire.
Annual cumulative FFDI, which integrates daily fire weather across the year,
increased significantly at 16 of 38 Australian sites from 1973-2010 (Clarke et al .
2012). The number of significant increases is greatest in the south east, while the
largest trends occurred inland rather than near the coast ( FigureĀ 3.4 ) . The largest
increases in seasonal FFDI occurred during spring and autumn, while summer
had the fewest significant trends. This indicates a lengthened fire season.
 
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