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Australian Climate: The Past 50 Years of Change
Mr Bruce Stewart
Assistant Director (Climate and Oceans)
Overview
• Observational data from the Bureau of Meteorology, CSIRO and peer organisations
• The past 50 years of change:• Human climate drivers - CO2 and Methane• Temperature• Rainfall• Ocean temperature• When were the hottest days and coldest nights• Sea level
Observing the Human Drivers of Climate Change
Little change until 1750 then an increase of more than 35%
Atmospheric Carbon Dioxide (ppm)
200
220
240
260
280
300
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360
380
400
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Year
Atm
os
ph
eri
c C
arb
on
Dio
xid
e
Observing the Human Drivers of Climate Change
Little change until 1750 then concentrations nearly triple
Atmospheric Methane (ppb)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Year
Atm
os
ph
eri
c M
eth
an
e
Australian Temperatures
• Temperature has increased by about 0.7 C since 1960• 2000 to 2009 was Australia’s warmest decade on record• 2005 was Australia’s warmest year on record, 2009 the second warmest
Annual and Decadal Mean Temperature Anomalies For Australia
-1.25
-1.00
-0.75
-0.50
-0.25
0.00
0.25
0.50
0.75
1.00
1.25
1960 1970 1980 1990 2000 2010
Year
Tem
per
atu
re A
no
mal
ies
(°C
) Decadal mean
Departures from 1961-90 normal
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
Australian Rainfall
• Averaged over Australia, rainfall has increased by 10% in the past 50 years• Wet periods in the 1970s and late twentieth century were associated with La Niña events
Annual and Decadal Mean Rainfall For Australia
100
200
300
400
500
600
700
800
900
1960 1970 1980 1990 2000 2010Year
Rai
nfa
ll (m
m)
Decadal mean
Australian Rainfall
• Substantial increases in many parts of northern and central Australia• Substantial decreases across much of southern and eastern Australia
Sea Surface Temperatures
• Strongest warming trends are in the Tasman Sea and Indian Ocean• Total warming in these areas has reached up to 1C
Sea Surface Temperatures
• Sea Surface Temperatures around Australia have increased by about 0.4C in the past 50 years
• 1998 was particularly warm, reflecting the very strong El Niño
Annual and Decadal Sea Surface Temperature For Australian Region
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
1960 1970 1980 1990 2000
Year
Tem
per
atu
re A
no
mal
ies
(°C
)
Decadal mean
Changes in Maximum Temperature Extremes
• Highest daily maximum temperatures tend to occur in recent years• More sites recorded highest daily maximum temperatures in 2009 than in any other year
Distribution of High Maximum Temperatures
0
10
20
30
40
50
60
1960 1970 1980 1990 2000Year
Nu
mb
er
in E
ac
h Y
ea
r Decadal mean
Changes in Maximum Temperature Extremes
• Lowest daily maximum temperatures tend not to occur in recent years
Distribution of Low Maximum Temperatures
0
10
20
30
40
50
60
1960 1970 1980 1990 2000Year
Nu
mb
er
in E
ac
h Y
ea
r Decadal mean
Change in Sea Level
• Sea level rise averaged over the Australian region has been slightly less than the global rise
• During 1993 to 2009, sea level rise has been 1.5 to 3 cm/decade in the south and east and 7 to 9 cm/decade in the north and west
-100
-50
0
50
100
150
1860 1880 1900 1920 1940 1960 1980 2000 2020Year
Glo
bal
Mea
n S
ea
Lev
el (
mm
)
Change in Sea Level
• Sea level rise averaged over the Australian region has been slightly less than the global rise
• During 1993 to 2009, sea level rise has been 1.5 to 3 cm/decade in the south and east and 7 to 9 cm/decade in the north and west
Global Mean Sea Level from Satellite
y = 3.0625x - 6120.6
-30
-20
-10
0
10
20
30
40
50
1990 1995 2000 2005 2010
Year
Glo
bal
Mea
n S
ea L
evel
(m
m)
In Summary
• Data from the Bureau, CSIRO and peer organisations shows a picture of pervasive and consistent trends
• The trends are continuing
• The quality of the data is high, and the base data are all available for scrutiny and analysis
• Obtaining data:
www.bom.gov.au and [email protected]
