Transcript Bruce Stewart - Presentation

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
Atmospheric Carbon Dioxide (ppm)
Atmospheric Carbon Dioxide
400
380
360
340
320
300
280
260
240
220
200
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Year
Little change until 1750 then an increase of more than 35%
Observing the Human Drivers
of Climate Change
Atmospheric Methane (ppb)
2000
Atmospheric Methane
1800
1600
1400
1200
1000
800
600
400
200
0
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Year
Little change until 1750 then concentrations nearly triple
Australian Temperatures
Annual and Decadal Mean Temperature Anomalies For Australia
Temperature Anomalies (°C)
1.25
1.00
Decadal mean
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
• 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
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
Annual and Decadal Mean Rainfall For Australia
900
800
Decadal mean
Rainfall (mm)
700
600
500
400
300
200
100
1960
1970
1980
1990
Year
2000
2010
• 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
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 1C
Sea Surface Temperatures
Annual and Decadal Sea Surface Temperature For Australian Region
0.6
Temperature Anomalies (°C)
0.5
0.4
Decadal mean
0.3
0.2
0.1
0
-0.11960
-0.2
1970
1980
1990
2000
Year
-0.3
-0.4
-0.5
• Sea Surface Temperatures around Australia have increased by
about 0.4C in the past 50 years
• 1998 was particularly warm, reflecting the very strong El Niño
Changes in Maximum
Temperature Extremes
Number in Each Year
Distribution of High Maximum Temperatures
60
Decadal mean
50
40
30
20
10
0
1960
1970
1980
1990
2000
Year
• Highest daily maximum temperatures tend to occur in recent years
• More sites recorded highest daily maximum temperatures in 2009
than in any other year
Changes in Maximum
Temperature Extremes
Distribution of Low Maximum Temperatures
Number in Each Year
60
Decadal mean
50
40
30
20
10
0
1960
1970
1980
1990
2000
Year
• Lowest daily maximum temperatures tend not to occur in recent years
Change in Sea Level
Global Mean Sea Level (mm)
150
100
50
0
-50
-100
1860
1880
1900
1920
1940
Year
1960
1980
2000
2020
• 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
Change in Sea Level
Global Mean Sea Level (mm)
Global Mean Sea Level from Satellite
50
40
30
20
10
y = 3.0625x - 6120.6
0
-10
-20
-30
1990
1995
2000
2005
2010
Year
• 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
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]