Downscaled scenarios to support adaptation:
Alternative frameworks
2080s
IPCC Fourth Assessment Report (2007) temperature and rainfall
projections for 2080-2099 under SRES A1B
The dominant scientific paradigm
The cascade of uncertainty
Future
society
GHG
emissions
Climate
model
Regional
scenario
Impact
model
Local
impacts
Adaptation
responses
The envelope of uncertainty
Scientific reality…
The cascade of uncertainty
Future
society
GHG
emissions
Climate
model
Regional
scenario
Impact
model
Local
impacts
Adaptation
responses
Envelope of uncertainty
End-to-end uncertainty analysis
B2
CGCM2
CSIRO
HADCM3
CF
1.0
0.8
0.8
0.8
0.6
0.6
0.6
CDF
1.0
0.4
0.4
0.2
0.2
GCM
0.0
-50 -40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100
-50 -40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100
-50 -40 -30 -20 -10
CATCHMOD
REGMOD
2020s
0.8
0.8
0.8
0.6
0.6
0.6
CDF
1.0
CDF
1.0
0.4
0.4
Structure
10 20 30 40 50 60 70 80 90 100
Q95 (% change)
2050s
2080s
0.4
0.2
Parameters
0.0
0.0
0
10 20 30 40 50 60 70 80 90 100
Q95 (% change)
1.0
-50 -40 -30 -20 -10
0
Q95 (% change)
REGMOD
0.2
Downscaling
0.0
Q95 (% change)
CATCHMOD
SD
0.4
0.2
Emissions
0.0
CDF
ECHAM4
1.0
CDF
CDF
A2
0.2
All combined
0.0
-50 -40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100
Q95 (% change)
-50 -40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100
Q95 (% change)
Conditional probabilities of lower summer flows in the River Thames by the 2020s, 2050s
and 2080s. Source: Wilby and Harris (2006)
Observed
non-climatic
pressures
Social acceptability
Vulnerability
(now)
Adaptation
options
A, B, C....
Technical feasibility
Economic appraisal
Regulatory context
Adaptation principles
Performance appraisal
Vulnerability
(future)
Robust
measures
B, W
Adaptation
pathways
W then B
Climate change
narratives
Sensitivity analysis
New evidence
Monitoring
Preferred
measures
B, H, S, W
Narratives of
non-climatic
pressures
An
“adaptationcentred
paradigm”
Observed climate
variability and
change
Case study 1: Scenarios galore
Derwent Reservoir in summer 1995. Courtesy of Nick Jackoby
ClimatePrediction.net
Source: EA
(2009)
UKCP09 projections for 2010-2039
UKCP09 projections of summer mean temperature change
under B1 (left panel) and A1FI (right panel) emissions by the
2020s, for the 10th and 90th percentiles respectively.
UKCP09 projections for 2010-2039
2050s B1
90th percentile
2050s A1FI
10th percentile
Changes in
summer
mean totals
by 2050s.
Source:
UKCP09
Projected changes in river flow by the 2020s
20
15
10
Percent change
5
0
-5
-10
-15
-20
-25
-30
5
25
50
75
95
Median
Dry Scenario
Wet Scenario
Climate change flow factors for the River Itchen at Highbridge.
Data source: UKWIR (2007)
Evaluating
adaptation
options
Schematic of the Wimbleball water
resource zone. Reservoirs, river
abstraction points, and
groundwater sources are
represented by triangles, curvy
lines, and punched circle,
respectively. Solid circles
represent different demands.
WTW indicates water treatment
works, and the arrows show the
direction of flow between different
sources and demands.
Source: Lopez et al. (2009)
Risk of failure to meet water demand
The business as usual scenario for East Devon: the fraction of CP.net projections that fail
to meet average water demand in October under SRES A1B. Source: Lopez et al (2009)
Evaluating adaptation options
Scenario
BAU
DEM
RES
ALL
Baseline
19
4
12
1
2000s
33
8
25
4
2030s
51
20
41
11
2060s
77
36
61
22
Percentage of model runs with single year supply failure in East Devon
under SRES A1B emissions. Source: Lopez et al (2009)
Likelihood of achieving environmental flows*
* The minimum river flow should not fall below the
“hands off” flow of 198 Ml/d in MU5
Impact of climate change on achievement of target flows in the
River Itchen, Hampshire, UK. Source: EA (2009)
Case study 2: Major consequences
The traditional approach
to flood risk management....
Response to past floods in
Greenwich, London.
Source: EA (2009).
No projected trend in tidal surge
Annual maximum skew surge downscaled from four GCMs for the
period 1961-2100 under SRES A2 emissions (ensemble member M1).
UKCP09
SLR
projections
Relative sea level (RSL)
rise over the 21st century
showing central estimate
values (thick lines) and 5th
and 95th percentile limits
of the range of uncertainty
(thin lines) for four sample
locations around the UK.
Values are relative to 1990.
Source: Lowe et al. (2009)
...now adaptation pathways in TE2100
Source: Environment Agency
Case study 3: Crisis now
Photo: Bull (1930)
A region already facing water crisis
Djibouti
Morocco
Yemen
Australia
Population* (1000)
793
31,478
20,975
21,074
Growth rate (%)
2.1
1.5
3.1
1.0
Water per capita (m3/yr)
378
921
195
18372
GDP agriculture (%)
4
16
13
3
Rural water access (%)
59
56
65
100
Source:
United Nations
Statistics
Division (2005)
* 2008
Limited data availability
Active rainfall stations in the Ministry of Agriculture and Irrigation network (2007)
Total annual precipitation (mm)
No consensus about rainfall projections
1200
1000
800
600
400
200
0
1960
1980
2000
2020
2040
2060
2080
2100
Projected annual total precipitation at Masna’ah under SRES A2 emissions. The 15-member
ensemble mean and 90% confidence range are shown by heavy and light black lines
respectively. Individual GCMs are shown by the coloured lines.
Measures to improve knowledge base
1. Centralise meteorological data collection, quality control and dissemination
2. Support meteorological data rescue and digitization
3. Monitor baseline and environmental change (indicators) at reference sites
4. Improve surface and groundwater models for sustainable resource
estimation
5. Integrate remotely sensed weather variables with catchment models
6. Improve understanding of regional climate and land surface feedbacks
7. Diagnostic testing of model skill for present/past climate
8. Develop real-time, seasonal and decadal forecasting capability*
9. Improve the dissemination and uptake of forecasts for emergency response
10. High resolution surveys of zones most vulnerable to climate hazards (such
as coastal and fluvial flooding)
* where there is demonstrable skill
Portfolio of measures to address water deficit
1. Strengthen water governance and law, methods of permission and allocation
2. Identify and protect recharge zones from pollution and/or salinization
3. Increase agricultural (and urban) drainage water re-use
4. Manage artificial aquifer recharge, especially in the coastal zone
5. Rehabilitate and maintain assets (leakage control, urban drainage systems)
6. Improve water efficiency of all sectors (domestic, agricultural, industrial)
7. Develop faster growing and/or more drought resistant cultivars
8. Adjust cropping calendar, crop mix and area planted to new conditions
9. Employ traditional rain water harvesting and retention (terracing, mulching)
10. Establish and review drought management plans
11. Identify and meet ecosystem water needs
12. Establish water-sharing commissions for transboundary resources
Concluding remark: Two important questions
What (if any) value will be added to the risk
assessment or adaptation plan by investing time
and effort in regional climate downscaling?
Given the uncertainties involved, are there
simpler ways of selecting and testing the
robustness of adaptation interventions?