Download Impact of Climate Change on Water Resources

Impact of Climate Change on
Water Resources
Water Corporation Technical Seminars
10 July 2006
Brian Ryan
CSIRO Marine and Atmospheric Research
www.csiro.au
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
1946
1948
1945
1972
1890-99
Year
1940-45
199
0
198
0
197
0
196
0
195
0
194
0
193
0
192
0
1967
191
0
190
0
110 1893
100
1891
90
80
70
1894
60
50
40
30
20
10
0
189
0
Number of stations
Abrupt shifts in Australian annual rainfall
Total
Positive
1967-69
How has the rainfall of South-western
Western Australia changed?
May-July SW WA Rainfall
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 largescale 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 1.45.8oC between 1990 and 2100
 Projected warming of 0.541.24oC between 1990 and
2030
 Projected warming of 1.173.77oC 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
SWWA: Range of projections for changes of
temperature from nine international models
May to October
SRES
550 ppm
450 ppm
2030
0 1 2 3 4 5 6 7 8
0 1 2 3 4 5 6 7 8
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
Temperature Change (oC)
Temperature Change (oC)
2070
0 1 2 3 4 5 6 7 8
o
Temperature Change ( C)
November to April
0 1 2 3 4 5 6 7 8
0 1 2 3 4 5 6 7 8
Temperature Change (oC)
Temperature Change (oC)
SWWA: Range of projections for changes of rainfall
from nine international models
SWWA Precipitation changes with 9 GCMs
May to October
SRES
550 ppm
450 ppm
2030
-80 -60 -40 -20 0 20 40 60 80 -80 -60 -40 -20 0 20 40 60 80 -80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
Rainfall Change (%)
Rainfall Change (%)
2070
-80 -60 -40 -20 0 20 40 60 80 -80 -60 -40 -20 0 20 40 60 80 -80 -60 -40 -20 0 20 40 60 80
Rainfall Change (%)
November to April
Rainfall Change (%)
Rainfall Change (%)
Some Weather Types
Type 3
L
1012
.2 .4 .6 .8 1
1016
H
H
1016
1012
1004
1000
1008
Type 5
L
.2 .4 .6 .8
1012
1
1016
1020
H
1016
1012
SWWA winter weather state probabilities
from stochastic downscaling of Mk3
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
(A2 dots, B2 small dash, B1 medium dash, A1B long dash and ‘committed’ dot-dash).
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 warming (%)
South-west
20.0
10.0
0.0
-10.0
-20.0
Jan
Feb
Mar
Apr
May
Jun
Evaporation
Change per degree global warming
Jul
Aug
Rainfall
Sep
Oct
Nov
Dec
P and Ep change over Australia
(per degree global warming)
10.0
North-east
Change per degree warming (%)
Change per degree warming (%)
North-west
20.0
0.0
-10.0
NW
-20.0
Jan
Feb
Mar
Apr
May
Jun
Jul
Evaporation
Aug
Sep
Oct
Nov
Dec
NE
Rainfall
20.0
10.0
0.0
-10.0
-20.0
Jan
Feb
Mar
Apr
May
Jun
Jul
Evaporation
20.0
Aug
Sep
Oct
Nov
Dec
Sep
Oct
Nov
Dec
Sep
Oct
Nov
Dec
Rainfall
10.0
SW
0.0
-10.0
-20.0
Jan
Feb
Mar
Apr
May
Jun
Evaporation
Jul
Aug
Rainfall
Sep
Oct
Nov
Dec
SE
Change per degree warming (%)
South-east
20.0
10.0
0.0
-10.0
-20.0
Jan
Feb
Mar
Apr
May
Jun
Jul
Evaporation
Tasmania
Tas
Change per degree warming (%)
Change per degree warming (%)
South-west
Aug
Rainfall
20.0
10.0
0.0
-10.0
-20.0
Jan
Feb
Mar
Apr
May
Jun
Evaporation
Jul
Aug
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 sensitivity
Model comparison
0.0
1.0
2.0
3.0
4.0
5.0
B Factor (Potential Evap)
0.5
0.0
-0.5
-1.0
-1.5
-2.0
Simhyd
-2.5
AWBM
Zhang01
-3.0
A Factor (Rainfall)
pp
er
M
ur
ra
Ki y
ew
O a
ve
Br ns
G oke
o
n
C ulb
am ur
pa n
s
Lo pe
dd
M
o
ur
ra Av n
y
M R oca
ur iv
ru er
i
La mb na
i
d
ke g
G ee
eo
La rge
c
Be hla
na n
W
n
im M ee
m a
er lle
a- e
Av
o
Bo n
rd
M er
oo
n
G ie
w
yd
M Ca Na ir
a
m
C cqu stle oi
on a re
da rie ag
m -B h
in og
e- a
C n
u
W lgo
ar a
re
g
Pa o
Lo D roo
w ar
er lin
M g
ur
ra
y
U
Change in mean annual flow (%)
Simple model of mean flow changes
– MDB (2030)
20
10
0
-10
-20
-30
-40
Vertical lines measure range from ten models with a global warming range from 0.541.24C. The central box is range of change at 0.85C (median) global warming
Provisional results relating runoff
response to climate change for the MDB
20
2100 WRE
10
2030 SRES
0
-10
-20
0
1
2
3
4
Mean Global Warming (°C)
5
-30
6
Mean Rainfall Change (%)
2100 SRES
25 to 50
25-50
0 to 25
0-25
-25 to 0
-25-0
-50 to -25
-50--25
<-50
-75--50
Mean
Runoff
Change
(%)
m
en
ny
C
ar
oa
st
k
R
Ke ive
r
Fr
n
an t R
kl
i
an ver
O
'S
ha d R
nn ive
r
o
W nR
iv
ar
er
re
n
D
on
R
iv
n
er
e
Bl
ac lly
kw Ri
ve
Bu oo
r
ss d R
el
i
to ver
n
Pr
C
es oa
st
to
n
C Riv
ol
lie er
H
ar Riv
M
er
v
ur
ra ey
R
y
i
R
iv ver
er
(
Av WA
on
)
R
Sw
iv
M
er
oo an
C
re
-H o as
ill
t
R
iv
er
s
D
ba
Al
Change in mean annual flow (%)
Simple model of mean flow changes
– SW WA (2030)
0
-10
-20
-30
-40
-50
-60
-70
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
5250
70%
4500
60%
3750
50%
3000
40%
2250
30%
1500
20%
750
10%
0
0%
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Percentage reduction in inflow (%) .
Volume reduction in inflow (ML) .
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.
Contact
Name: Dr Brian Ryan
Phone: 61 3 9333 6554
Email:[email protected]
Web: www.marine.csiro.au
Thank You
Contact CSIRO
Phone: 1300 363 400
+61 3 9545 2176
Email: [email protected]
Web: www.csiro.au
www.csiro.au