www.csiro.au
Impact of Climate Change on Water Resources
Water Corporation Technical Seminars10 July 2006
Brian RyanCSIRO Marine and Atmospheric Research
Acknowledgements
IOCI Colleagues
Bureau of Meteorology,
CSIRO Marine and Atmospheric Research,
CSIRO Land and Water,
CSIRO Mathematics and Information Sciences,
Brian Sadler and Ed Hauck
And specifically Roger Jones (CMAR) for work on impact of climate change on water resources in Australia
Impact of Climate Change on Water Resources
•How has climate change?
•Is the evidence for anthropogenic climate change? (Greenhouse Gases and Aerosols)
•What can we say about the future climate?
•What is the likely impact of climate change on water resources?
•What are the threats to the water sector of climate change?
IPCC Third Assessment Report
‘An increasing body of observations give a collective picture of a warming world and other changes to the climate system’
How have surface temperatures changed?
How have sea surface temperatures in the Indian Ocean Basin changed?
How has Australian rainfall changed?
http://www.bom.gov.au/silo/products/cli_chg/index.shtml
Abrupt shifts in Australian annual rainfall
1891
1893
19721894
1967
1946
1945
1948
0102030405060708090
100110
Year
Num
ber
of s
tatio
ns
TotalPositive
1890-99
1940-45 1967-69
May-July SW WA Rainfall
How has the rainfall of South-western Western Australia changed?
Time series of SWWA rainfall (mm). Solid trace depicts early winter (May to July) totals and dotted trace late winter (August to October) totals. Means for the periods 1900 to 1974 and 1975 to 2004 are represented by horizontal lines.
How has the frequency of “wet” synoptic patterns (& June-July rainfall) changed?
Decrease in frequency of “wet” types accounts for ~50% of rainfall decrease
Decrease in rainfall associated with “troughs to west” types accounts for ~30%
Summary of how the Regional Climate of SWWA has changed.
Temperatures have increased by about 0.8C since 1910 with most of increase since 1950
Daily minimums have increased more than daily maximums
Sea surface temperatures in the averaged over the Indian Ocean basin have increased by 0.6C
Since 1970 the number of storms have decreased and they bring less rain
Annual rainfall has decreased by 10% since 1970s
May-July rainfall has decreased by 15% since 1970s
Reduced rainfall has resulted in 50% less runoff
Key Message: Water managers can not assume that the climate baselines of the 20th century will be valid in the 21st century
Is it possible to model the observed temperature and rainfall changes?
What can we say about the attribution of the drying in SWWA
The decline in the number of storms is linked with large-scale global circulation changes (in about 1970);
It is feasible that the drying trend could have been the result of unforced climate variability;
However, the decline in rainfall is also consistent with the modelled effect of anthropogenic forcing;
Changes in land cover may also have contributed to the rainfall decline.
What can we say about the future?
Emission scenarios
Global Temperature Rise
Global temperatures and sea level are projected to rise under all IPCC emission scenarios
Projected warming of 1.4-5.8oC between 1990 and 2100
Projected warming of 0.54-1.24oC between 1990 and 2030
Projected warming of 1.17-3.77oC between 1990 and 2070
At least half of uncertainly relates to uncertainties in emissions, the rest to uncertainties in climate science
Changes will persist for centuries
SRES 550 ppm 450 ppmMay to October
November to April
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
2030
2070
SWWA: Range of projections for changes of temperature from nine international models
SWWA: Range of projections for changes of rainfall from nine international models
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
-80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
SWWA Precipitation changes with 9 GCMs
SRES 550 ppm 450 ppmMay to October
November to April
2030
2070
Some Weather Types
1016
1000
1012
1008
1016
1004
1012
Typ
e 5
Typ
e 3
.2 .4 1.8.6
.2 .4 .6 1.8
H H
L
1016
1016
1012
1020
1012
H
L
SWWA winter weather state probabilities from stochastic downscaling of Mk3
(A2 dots, B2 small dash, B1 medium dash, A1B long dash and ‘committed’ dot-dash).
Winter Seasonal Totals
(% of median for 30 SWWA rainfall station)
Scenario 2030-2064
A2 80-90%
B2 84-91%
A1B 87-91%
B1 97-99%
S(20) 96-99%
Baseline 1975-2004
Key Message
The climate change simulations show
that even with the lowest conceivable greenhouse gas emission scenarios,
the south-west of Western Australia is projected to be drier and warmer later in the century,
with an increasing probability of dry weather patterns and a decreased probability of wet weather patterns
P and Ep changes for south-western Australia
Change per degree global warming
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation Rainfall
P and Ep change over Australia(per degree global warming)
NW NE
SE
Tas
SW
North-west
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation Rainfall
South-west
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation Rainfall
North-east
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation RainfallSouth-east
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation RainfallTasmania
-20.0
-10.0
0.0
10.0
20.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Cha
nge
per
degr
ee w
arm
ing
(%)
Evaporation Rainfall
What is the likely impact of climate change on water resources?
Hydrological model sensitivity
Relate change in mean annual rainfall and potential evaporation to mean annual change in runoff (%)
∂Q = ∂P × A + ∂Ep × B
The further A and B are from zero, the more sensitive that factor is
Hydrological model sensitivityModel comparison
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
0.0 1.0 2.0 3.0 4.0 5.0
A Factor (Rainfall)
B F
act
or
(Po
ten
tial E
vap
)
Simhyd
AWBM
Zhang01
Simple model of mean flow changes – MDB (2030)
-40
-30
-20
-10
0
10
20
Upper
Mur
ray
Kiewa
Ovens
Broke
n
Goulbu
rn
Campa
spe
Lodd
on
Avoca
Mur
ray R
iverin
a
Mur
rum
bidge
e
Lake
Geo
rge
Lach
lan
Benan
ee
Mall
ee
Wim
mer
a-Avo
n
Borde
r
Moo
nie
Gwydir
Namoi
Castle
reag
h
Mac
quar
ie-Bog
an
Conda
mine
-Culg
oa
War
rego
Paroo
Darlin
g
Lower
Mur
ray
Cha
nge
in m
ean
annu
al f
low
(%
)
Vertical lines measure range from ten models with a global warming range from 0.54-1.24C. The central box is range of change at 0.85C (median) global warming
Provisional results relating runoff response to climate change for the MDB
0 1 2 3 4 5 6
20
10
0
-10
-20
-30
Mean Global Warming (°C)
Mea
n R
ain
fall
Cha
nge
(%)
25-50
0-25
-25-0
-50--25
-75--50
2030 SRES
2100 WRE
2100 SRES
25 to 50
0 to 25
-25 to 0
<-50
-50 to -25
Mean Runoff
Change (%)
-70
-60
-50
-40
-30
-20
-10
0
Albany
Coa
st
Denm
ark R
iver
Kent R
iver
Frank
land
River
O'Sha
nnon
Rive
r
War
ren
River
Donne
lly R
iver
Blackw
ood
River
Busse
lton
Coast
Presto
n Rive
r
Collie
River
Harve
y Rive
r
Mur
ray R
iver (
WA)
Avon
River
Swan C
oast
Moo
re-H
ill Rive
rs
Cha
nge
in m
ean
annu
al f
low
(%
)
Simple model of mean flow changes – SW WA (2030)
Vertical lines measure range from ten models with a global warming range from 0.54-1.24C. The central box is range of change at 0.85C (median) global warming
Reduction in mean monthly inflow to Stirling Dam (Berti et al 2004) using the current (1982-2002)and future (2042-2062) GCM simulations
0
750
1500
2250
3000
3750
4500
5250
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Vol
ume
redu
ctio
n in
infl
ow (M
L)
.
0%
10%
20%
30%
40%
50%
60%
70%
Perc
enta
ge re
duct
ion
in in
flow
(%) .
Flow change (ML)Flow change (%)
Annual % decrease in stream flow is 31%
IOCI “Living with our changing climate workshop”
Key Impacts on Water Sector Reduced reliability of public supply
Reduced reliability of private supply
Reduced stream and estuary flow and water quality reducing ecological and social values
Drying of ground water reliant systems
Reduced water availability for fire fighting
Challenged regulatory and management systems
Seasonally variable flooding
Stranded underperforming assets and infra structure
IOCI “Living with our changing climate workshop”
Water Sector Climate Science Priorities Better understanding of the dynamics of climate change
and variability, including rainfall for south-west WA, to provide data for policy and planning;
Developing of probabilities around climate scenario estimates;
Distinguishing between climate change and climate variability;
Differentiating effects on summer and winter rainfall;
Breaking down spatial trends between north to south and east and west, and even within the south-west; and
Understanding of meteorological shifts that have or will occur.
www.csiro.au
Thank You
Contact
Name: Dr Brian RyanPhone: 61 3 9333 6554Email:[email protected]: www.marine.csiro.au
Contact CSIRO
Phone: 1300 363 400+61 3 9545 2176Email: [email protected]: www.csiro.au
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