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Climate Adaptation:
Risk, Uncertainty and Decision-Making
Dr. Robert Willows
Environmental Forecasting Manager
National Centre for Risk Analysis and Options Appraisal
Climate Change
Policy
Policy
Sequestration
Policy
Emissions
Uncertainty
Uncertainty
Energy Supply
Energy Demand
Climate
Variability
Tools
Risk Analysis
Forecast Models
Options Appraisal
Policy Analysis
Uncertainty Analysis
Sensitivity Analysis
Impacts
-ve
Adaptation
Uncertainty
Policy
Scenarios
Uncertainty
Scenarios
Policy
Uncertainty
Economic and
Social Issues
and
Development
National Centre for Risk Analysis and Options Appraisal
Policy
Study objectives
• Help identify ‘climate-sensitive’ decisions
• Help achieve better decisions
• Provides guidance on the use of tools and techniques
• Should provide generic guidance on climate risks
• Consistent with DETR guidelines for Environmental
Risk Assessment (‘Greenleaves 2’)
Decision/
Policy
makers
Science
UKCIP Technical Report
•
Part 1 : A review of
Climate Adaptation: Risk,
Uncertainty and Decision Making
– Risk and uncertainty
– Decision-making under uncertainty
– Risk-based climate impact assessment
•
Part 2 : Framework and Guidance
– Stage by Stage guidance to support
the process of undertaking risk-based
appraisal of climate influenced
decisions
National Centre for Risk Analysis and Options Appraisal
Decision Making Framework
Climate change
issue
Climate change
policy
Climate change
research, monitoring
Identify
problem
Establish criteria for
decision-making
Monitor
Climate change
scenarios
Risk
assessment
Vulnerability
assessment
Implement
decision
Options
appraisal
Make decision
Climate change
application
No
No
Yes
Identify
options
Adaptation
strategies
Problem
defined
correctly ?
Objectives
met ?
Yes
Climate change
policy
Socio-economic
scenarios
Data information
collection
Impact
assessment
Risk = Hazard * Consequence
HAZARD … PATHWAY … RECEPTOR
Consequences
C2.1
Climate
C1.1
C3.1
Non-Climate
C1.2
Decision
Criteria
C1.3
C3.2
C4.1
National Centre for Risk Analysis and Options Appraisal
Hazard … Risk … and … Uncertainty
1
Probability
(cumulative)
?
0
Large
Small
Magnitude
National Centre for Risk Analysis and Options Appraisal
Risk … and Uncertainty
High
High Risk
Hazard
Low
Low Risk
Large
Small
Consequence
National Centre for Risk Analysis and Options Appraisal
Risk … and Uncertainty
good
Ambiguity
Quantitative Risk
Ignorance
of risk
Uncertainty
of likelihood
Knowledge
of Hazard
poor
poor
good
Knowledge of
Consequence
National Centre for Risk Analysis and Options Appraisal
Risk Prioritisation –
Temporally-dynamic risks
High
Higher priority
Past
or
Present
risk
Act sooner
Low
Low
Rate of change of risk
or
future risk
High
National Centre for Risk Analysis and Options Appraisal
Climate sensitive decisions
Large
Significance
of
climate change
or
climate
variable(s)
Climate
adaptation
decisions
Moderate
Climate
influenced
decisions
Climate independent decisions
None
None
Moderate
Large
Significance of non-climate factors or
non-climate variable(s)
National Centre for Risk Analysis and Options Appraisal
Decision errors?
Perceived
importance
of factors
Large
Climate
factors
Actual
Importance of
factors
Over-adaptation
Under-adaptation
Actual
Importance
of factors
Perceived
importance
of factors
None
None
Moderate
Large
Non-climate factors
Perceived
importance
of factors
Mis-adaptation
Actual
Importance
of factors
Actual
importance
of factors
Mal-adaptation
National Centre for Risk Analysis and Options Appraisal
Perceived
importance
of factors
Adaptation strategies under Uncertainty
Optimistic
–
The option the may produce the best
adaptation outcome
MaxiMax
Precautionary
–
The option associated with the most
favourable of the least favourable
possible outcomes
MaxiMin
Least Regret
–
That option associated with the lowest
lost opportunities or regret
MiniMax
Regret
No-regret
–
The best adaptation option under all
possible outcomes
‘Risk Averse’
National Centre for Risk Analysis and Options Appraisal
Generic options for climate risk management
•
Wider use of risk assessment, forecasts and options appraisal
– preferably proactive technical response
•
Delay and buy-time
– proactive technical response to reduce uncertainty
•
Research  e.g. modelling, technology, ‘adaptive capacity’
•
Monitoring
– system performance monitoring - proactive technical response
– climate impact monitoring - reactive technical response
•
Data and information supply, and education, awareness raising
– proactive and reactive
•
Contingency planning
– low probability, high consequence events
– strategic planning response
National Centre for Risk Analysis and Options Appraisal
Generic options for climate risk management
•
Diversification or bet-hedging
– proactive technical or policy response
•
Insurance  proactive, fiscal response
•
Defend and Manage - reactive technical measures
•
Change of use
– proactive or reactive, planning response +/- technical measures
•
Retreat and Abandon
– strategic planning response
•
Safety factors, climate headroom, buffering measures
– technical and regulatory response
National Centre for Risk Analysis and Options Appraisal
Decision Making Framework
Climate change
issue
Climate change
policy
Climate change
research, monitoring
Identify
problem
Establish criteria for
decision-making
Monitor
Climate change
scenarios
Risk
assessment
Vulnerability
assessment
Implement
decision
Options
appraisal
Make decision
Climate change
application
No
No
Yes
Identify
options
Adaptation
strategies
Problem
defined
correctly ?
Objectives
met ?
Yes
Climate change
policy
Socio-economic
scenarios
Data information
collection
Impact
assessment
Risk screening
- climate variable checklist
•
Helps to both identify (Table 1) and define the different
characteristics (Table 2) of potentially significant or relevant
climate variables
•
Includes preliminary assessment of sensitivity and confidence
•
Useful for screening of variables
•
Not constrained by availability of climate forecast variables (e.g.
from GCM’s or RCM’s)
•
Encourages rigorous analysis of climate influence
•
Table 1 is not complete - proxy and compound variables will
depend on nature of particular assessment
National Centre for Risk Analysis and Options Appraisal
Climate variable checklist
Types of variables
Examples
• Primary
CO2, sea-level, temperature, precipitation, wind, cloud cover
• Synoptic
Weather types, pressure, storm track, lightning
• Compound
Humidity, evapotranspiration, mist, fog, growth season
• Proxy
Soil Moisture, river flow, wave climate
National Centre for Risk Analysis and Options Appraisal
Climate variable checklist
Characteristics of variables
Examples
• Magnitude and Direction Increase, decrease, rate of change
• Statistic
Average, time-integrated, variability and frequency
• Averaging period
Instantaneous ... hourly …. Annual …..decadal
• Joint probability events
and variables
Consecutive, coincident or joint occurrence,
correlation
National Centre for Risk Analysis and Options Appraisal
(Climate) Influence diagrams
Climate
Global
temperature
Mean water
level
Atmospheric
pressure
Tides
Land level
Rainfall,
freeze/thaw,
wave damage,
animal activity,
vegetation
Wind speed
direction
Surges
‘Everyday’
wave climate
Extreme water
level climate
Extreme wave
climate
Beach
morphology
Changes to
structure
Water
level
Structure
Flood
event
Waves
Beach
state
Overtop
Breach
Flood
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Describing confidence …..
Quantitative
probabilistic
descriptor
P > 95%
Subjective descriptor
Hazard
Certainty
‘Highly
probable’ ‘Very
likely’
‘Certain’,
‘Known’
‘Reliable’
75% < P < 95%
‘Likely’ to
‘Probable’
‘Confident’
25% < P < 75%
‘Possible’
‘Plausible’
‘Debatable’
5% < P < 25%
‘Unlikely’ to
‘Improbable’
‘Not
confident’
‘Uncertain’
‘Doubtful’
P < 5%
‘Impossible’
Theoretical
basis or
model
Established,
Validated
model
Information
or
data
Experimental
Peer
acceptance
Colleague
acceptance
Processbased model,
underpinned
by some
theory
Black box
and
Simulation
models
Absolute
‘All but
cranks’
Historical
or
Observation
High
‘All but
rebels’
3
Calculated
Medium
‘Different
schools’
2
Statistical
models
Fuzzy
models
Educated or
expert guess
Low
‘New field’
1
Concepts and
definitions
Uneducated
or nonexpert guess
None
‘No
opinion’
0
National Centre for Risk Analysis and Options Appraisal
Pedigree
rank
score
4
Downscaling 1
•
Space:
GCM  site
•
Time:
Monthly  daily
National Centre for Risk Analysis and Options Appraisal
SDSM - Statistical Down-Scaling Model
(Rob Wilby, Kings College London)
–
Daily data - observed data at site
–
Model - site data and large-scale data from GCM
–
Scenario - generate ensembles of daily time series
Maximum daily rainfall (mm)
30
Observed
25
rainfall (mm)
Modelled
Scenario
20
15
10
5
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
National Centre for Risk Analysis and Options Appraisal
Dec
Downscaling - Flood return period
prediction
1860 climate
2000 climate
2090 climate
National Centre for Risk Analysis and Options Appraisal
Scenario analysis and risk assessment
Q. Can we create scenarios which reflect changes in
variability as well as the mean?
A. YES - but it is difficult… and scenarios remain contingent on
assumptions and non-quantified uncertainties
Q. Can we assign probabilities to different scenarios?
A. Probably. Expert judgement can be used to assign probability to
the range encompassed by any two scenarios … but uncertainty
components within suite of scenarios have to be well-posed
National Centre for Risk Analysis and Options Appraisal
Estimating “probabilities” of different futures
We typically use a small
number of scenarios
If we make assumptions about the likelihood of different emissions
futures, use many more climate models, and incorporate the
effects of natural climatic variability, we can generate many more
scenarios
National Centre for Risk Analysis and Options Appraisal
Incorporating climate change into
water resources management
The future hydrological resource base will not be the same
as the present resource base
Mean climate will be different, due to climate change and
natural climatic variability
Variability in climate will be different. Altered frequency of
successive dry years?
….but we don’t know how different….
National Centre for Risk Analysis and Options Appraisal
Influence diagrams
- water resource management
land use
change
management
objectives
demand
Supply-side
baseline
data
hydrological
model
water
resources
model
reliability
Demand-side
Climate
change
adaptive response
National Centre for Risk Analysis and Options Appraisal
Use of socio-economic scenarios
000s of Ml/d
35
30
25
20
Water resources for the future
15
A STRATEGY FOR ENGLAND AND WALES
10
March 2001
5
0
1997/98
Forecast demand in 2025
National Centre for Risk Analysis and Options Appraisal
Coping with uncertainty
1.
Flexible management approaches
- review situation and adjust plans if appropriate
- continued monitoring
2.
Improved seasonal forecasts
- based on understanding of causes of seasonal
climatic variability
3.
Scenario analysis and risk assessment
National Centre for Risk Analysis and Options Appraisal
Conclusions and recommendations
(for decision-makers)
• Emphasis on understanding impact of present-day
observed climate variability
• Future climate change is only one source of decision
uncertainty
• Assessment of climate risk should be hierarchical
/tiered
• Climate adaptation should be iterative
• Assumptions and sources of uncertainty should be
treated explicitly in risk and impact assessments in
order to reach robust decisions
National Centre for Risk Analysis and Options Appraisal