Geoscience Reference
In-Depth Information
Projected changes in total tropical cyclone numbers, cyclone days, duration
of a given cyclone, genesis latitude and decay latitude for seven simulations,
downscaled using CCAM to 65 km grid spacing, for the period 2051-90,
relative to 1971-2000
Number
Days
Duration
(days)
Genesis (degrees
latitude)
Decay (degrees
latitude)
ECHAM5
2
58%
2
59%
2
0.4
2
1.1
2
1.3
GFDL CM2.0
2
53%
2
55%
2
0.3
2
0.8
2
1.1
GFDL CM2.1
2
40%
2
52%
2
1.0
2
1.4
2
1.2
MIROC3.2 (medres)
2
68%
2
73%
2
0.8
2
1.1
2
2.0
CSIRO Mk3.5
2
39%
2
44%
2
0.2
2
0.5
2
0.2
UK HADCM3
2
50%
2
47%
1
0.2
2
0.7
2
1.7
CSIRO Mk3.0
2
28%
2
23%
1
0.2
2
0.8
2
1.9
Average
2
48%
2
50%
2
0.3
2
0.9
2
1.3
Source: Abbs, 2010
Note
a Bold values indicate changes in cyclone numbers that are statistically significant at
the 99 per cent level.
Conclusions
Australia's vulnerability to extreme weather events is evident in recent disasters.
Changes in such weather events, and changes in exposure and vulnerability, can
alter the impact of disasters.
Observational evidence of changes in extreme weather events over recent
decades has been found globally and in Australia. From 1910-2011 the frequency
of extreme high temperatures in Australia increased while the frequency of
extreme low temperatures decreased. Increases in fire weather from 1973-2010
are significant at 16 of 38 Australian sites, mainly in the south east, with a
lengthened fire season. A decrease in late autumn and winter rainfall across
southern Australia in recent decades has likely been associated with an exacer-
bation of hydrological drought conditions during that time. There has been a
slight increase in heavy precipitation days across eastern Australia. An increase
in extreme sea levels has occurred since 1970. Since 1981, no significant trends
in the total numbers of cyclones, or in the proportion of the most intense
cyclones, have been found in the Australian region.
In a Four Degree World, Australia is expected to experience a large increase
in extremely high temperatures, extreme fire weather, extreme rainfall events,
tropical cyclone intensity, extreme sea levels, droughts in southern areas and hail
along the east coast. A decrease in the frequency of extremely cold temperatures
is expected, along with fewer tropical cyclones and a reduction in extreme winds
and hail in southern Australia.
