The Monash Sustainability Institute, the Melbourne Sustainable Society Institute, and the Australian
Meteorological and Oceanographic Society present:
How extreme is the recent extreme weather?
Dr Karl Braganza
Climate Monitoring Manager
Bureau of Meteorology, National Climate Centre
The IPCC scientific conclusions
IPCC 2007:
“Warming of the climate system is unequivocal.”
“Most of the observed increase in globally averaged temperatures since the
mid-20th century is very likely due to the observed increase in
anthropogenic (human) greenhouse gas concentrations.”
Australian Temperatures
All of Australia has
experienced warming over
the past 50 years
Some areas, have
experienced a warming of
1.5 to 2 C
Annual and Decadal Mean Temperature Anomalies For Australia
Temperature Anomalies (°C)
1.25
1.00
Decadal mean
Warming, as measured by
decadal averages, has been
constant since the middle of
last century
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
-1.25
1960
Departures from 1961-90 normal
1970
1980
1990
Year
2000
2010
Normal Distribution (Bell Curves) for height from
two different population samples- Males and
Overlap in
Females
Measure of
Trait.
Average
Male
Number of Individuals
Average
Female
But greater
incidence in
females
Clear
difference in
Measure of
Trait
Short
Tall
Height at Age 8 (Measure of Trait)
Shift in the frequency of warm weather events
Number of days per year
1955
2005
Increase in the
average maximum
temperature
Same old warm
weather; but much
more of it
Weather we
don’t see
anymore
Weather that is
outside our
historical
experience
Maximum Temperature
Number of days sequentially above 20 degrees C
Changes Temperature
Extremes
Consecutive Days Above 20 in Melbourne
140
120
100
80
Locations across Australia
have experienced less cold
weather in recent decades
60
40
20
0
1855
1865
1875
1885
1895
1905
1915
1925
1935
1945
1955
1965
1975
1985
1995
2005
Y
Year
Number in Each Year
Australian Maximum Temperature Records
60
Decadal mean
50
There is a trend in record heat
events for Australia.
40
More sites recorded highest
daily maximum temperatures
in 2009 than in any other
year
30
20
10
0
1960
1970
1980
1990
Year
2000
More frequent and severe heat waves
Return Periods (Recurrence Interval)
Indicate the Historical Frequency of an Event.
Small Shifts can have Large Effects:
Case Study: Black Saturday, Melbourne 2009
Mortality versus Maximum
Temperature
46.4°C
Nicholls (2010)
173 Deaths
from
Bushfires,
414 Injured.
374 Deaths
from
Extreme
Heat
Vic Gov (Aged Care, 2010)
Consider the European Heat Wave of August 2003
Observed Temp. 10W-40E, 10N-50N
8
7
Observed T
HadCM3 Model runs
T anomaly (vs 1961-1990)
6
5
Risk in 60
years?
4
30,000 deaths
Cost US$1.2bn
3
Average
climate in
~35 years
2
1
0
-1
-2
1875
1900
1925
1950
1975
2000
2025
2050
2075
2100
Source of data: UK Met Office
Intensification of the Hydrological Cycle
Globally averaged mean water vapour, evaporation and
precipitation are projected to increase.
Rainfall will increase in
the Tropics (monsoonal
regions).
Rainfall will be more
intense (heavy rainfall)
General decreases in
rainfall will occur over
the subtropics.
Even in areas where average rainfall decreases, rainfall intensity is
projected to increase; but there would be longer periods between
rainfall events.
Sea Surface Temperatures
Annual and Decadal Sea Surface Temperature For Australian Region
0.6
Sea Surface Temperature
Increases are consistent with
terrestrial warming.
Temperature Anomalies (°C)
0.5
0.4
Decadal mean
0.3
0.2
0.1
0
-0.11960
-0.2
-0.3
-0.4
-0.5
1970
1980
1990
Year
2000
Noting that the instrumentation
associated with ocean
monitoring is very different to
those on the land.
Strongest warming trends are
in the Tasman Sea and Indian
Ocean
Total warming in these areas
has reached up to 1C
A Primary Driver of
Australian Rainfall is Tropical
Sea Surface Temperature
Variability
SOND 2010
Rainfall Deciles.
ncep-reynolds
Darwin- wettest day
(367.6mm); wettest week
and wettest month in
February.
Carnarvon- Flooding mid
December
Extreme
Weather in
2010/2011
Tropical Cyclone Yasi
Double average rainfall
around Brisbane for
Spring and Summer
Heat wave records in
Sydney
South-west WA. Driest
year on record. Periods
of extreme heat.
Victoria; Flooding Sep,
Oct, Dec, Jan, Feb
“The Big Dry”
Parts of Australia have
recently experienced their
worst dry periods on record.
South East Australia; 1996-2010
South East Queensland; 19962010
South West Western Australia;
1970 - Present
The End