atmospheric research climate hazards & risk assessment roger n. jones aiacc kickoff meeting...
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Atmospheric Research
Climate Hazards&
Risk Assessment
Roger N. Jones
AIACC Kickoff Meeting Nairobi
February 11-14 2002
Atmospheric Research
What is a hazard?
Atmospheric Research
Typology of extreme climate events
Type Description Variable Measure
Simpleevents
Exceeding criticallevel on a continuousscale
Extreme rainfallTemperature
FrequencyReturn periodSequenceDuration
Complexevents
Weather eventscombining multiplevariables and/orresulting in multipleimpacts
Tropical cyclonesENSO eventsDrought
Frequency magnitudeSeverity ofimpacts
Singularevents
A possible futureclimatic state withpotentially extremeoutcomes
Cessation of deep-ocean circulationIce sheet collapse
Probability magnitude ofimpact
Atmospheric Research
Frequency of exceeding heat index threshold
50.0
60.0
70.0
80.0
90.0
1/10/98 31/10/98 30/11/98 30/12/98 29/01/99 28/02/99 30/03/99
Date
TH
I U
nits
THI72
THI78
Atmospheric Research
Current climate
Coping range
Vulnerability(drought)
Vulnerability(flood)
Atmospheric Research
Future climate - no adaptation
Coping range
Vulnerability(drought)
Vulnerability(flood)
Atmospheric Research
Future climate with adaptation
Coping range
Vulnerability(drought)
Vulnerability(flood)
Adaptation
Planning horizon
Policy Horizon
Atmospheric Research
Thresholds
A non-linear change in a measure or system, signalling a physical or behavioural change
Climate related thresholds are used to mark a level of hazard
Atmospheric Research
Thresholds
Biophysical• Tropical cyclone
• Coral bleaching
• ENSO event
• Island formation
• Island removal
Behavioural• Legal/regulatory
• Profit/loss
• Cultural
• Agricultural
• Critical
Atmospheric Research
Thresholds
• Link socio-economic criteria with biophysical criteria through a value judgement
• Provide a fixed point against which to measure climate uncertainty
• Directly link a particular impact to climatic variables
• Introduce criteria as defined by stakeholders into an impact assessment
Atmospheric Research
Critical thresholds
A level considered to represent an unacceptable degree of harm
This is a value judgement and may be decided by stakeholders, be a legal requirement, a safety requirement, a management threshold etc
Atmospheric Research
Metrics for measuring costs
• Monetary losses (gains)• Loss of life• Change in quality of life• Species and habitat loss• Distributional equity
Atmospheric Research
What is a risk?
Atmospheric Research
What is a risk?
Two uses
1. In general language
2. A specific operational meaning
Atmospheric Research
Characterising risk
UNEP definition
risk = hazard + vulnerability
vulnerability = exposure + susceptibility to loss
risk = f(hazard,likelihood)
Atmospheric Research
Uncertainty
Uncertainty and probability can be expressed in two ways:
1. Return period / frequency-based
2. Single event
Atmospheric Research
Return period / frequency-based probability
Recurrent eventWhere a continuous variable reaches a critical level, or
threshold.
Eg. Extreme temperature (max & min), Extreme rainfall, THI >72, >78, 1 in 100 year flood
Discrete eventAn event caused by a combination of variables (an
extreme weather event)
Eg. tropical cyclone/hurricane/typhoon, ENSO event
Atmospheric Research
Single event probability
Singular or unique eventAn event likely to occur once only. Probability refers to
the chance of an event occurring, or to a particular state of that event when it occurs.
Eg. Climate change, collapse of the West Antarctic Ice Sheet, hell freezing over
Atmospheric Research
What is the probability of climate change?
1. That it will occur• IPCC (2001) suggests that climate change is occurring with
a confidence of 66% to 95%
2. What form will climate change take?Uncertainties are due to:
• future rates of greenhouse gas emissions
• sensitivity of global climate to greenhouse gases
• regional variations in climate
• decadal-scale variability
Atmospheric Research
Uncertainty explosion
global climatesensitivity
emissionscenarios
regionalvariability
range ofpossible impacts
Atmospheric Research
CO2 emissions and concentrations
Simulated global warming: A2
Atmospheric Research
Global warming
Atmospheric Research
Mean sea level in the 20th century
Church et al. (2001)
Atmospheric Research
Sea level rise projections for one emission scenario(IS92a)
Church et al. (2001)
Atmospheric Research
SRES sea level rise to 2100
Atmospheric Research
Placing thresholds within scenario uncertainty
global climatesensitivity
emissionscenarios
regionalvariability
range ofpossible impacts
A
B
Atmospheric Research
Impact thresholds
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Year
Glo
ba
l W
arm
ing
(°C
)
Threshold A
Threshold B
Atmospheric Research
Complex system undergoing change
Pre-adapted state
Vulnerable state•M1
•M2
•M3
•M4
Atmospheric Research
Probabilistic structure of climate uncertainties
Critical threshold
Critical threshold
Time
Va
riab
le(s
)
Atmospheric Research
Linking key climatic variables to impacts
Climatevariable
Impactedactivity
Performancecriteria
Atmospheric Research
Production effects
THI between 79 and 88
THI between 72 and 78
mild stress no stress
moderate stress mild stress
Microsoft PowerPoint
Presentation
Atmospheric Research
Coral bleaching
• Caused by SST above a threshold• Expels xosanthellae algae• Severity related to days above
bleaching threshold• Corals may recover or die
Atmospheric Research
Critical thresholdsMacquarie River Catchment
Irrigation5 consecutive years below 50% allocation of
water right
Wetlands10 consecutive years below bird breeding
events
Atmospheric Research
P and Ep changes for Macquarie catchment
In change per degree global warming
-16.0
-8.0
0.0
8.0
16.0
J F M A M J J A S O N D
Cha
nge
fo
r 1
ºC g
lob
al w
arm
ing
(%
)
Evaporation (Ep) Rainfall (P)
Atmospheric Research
Irrigation allocations and wetland inflows- historical climate and 1996 rules
10,000
100,000
1,000,000
10,000,000
1890 1910 1930 1950 1970 1990
Year
Flo
w (
Gl x
10)
0
20
40
60
80
100
Irrig
atio
n al
loca
tion
(%)
Allocations Marshes
Atmospheric Research
Threshold exceedance as a function of change in flow (irrigation)
Change in mean average allocationSequences belowthreshold (years) +5% 0 -10% -15% -30% -40% -45%
1615 114 113 112 111 1 010 1 1987 16 1 15 2 2 14 2 2 4 53 1 1 1 2 4 1 12 5 4 6 6 5 6 21 10 13 11 12 7 4 4
Percent of total yearsbelow threshold
22 23 34 38 50 58 64
Atmospheric Research
Threshold exceedance as a function of change in flow (bird breeding)
Change in MAFSequences belowthreshold (years) +5% 0 -10% -15% -30% -40% -50%
16 115 1 1 214 1 1 213 1 2 312 1 2 311 1 110 1 1 1 198 17 1 1 1 16 2 15 1 1 1 1 2 14 3 2 2 3 4 2 33 2 1 3 4 3 3 12 4 7 4 2 2 11 4 3 7 5 3 3
Percent of total yearsbelow threshold 40 45 52 56 63 71 79
Atmospheric Research
Probabilities of flow changesclimate view
0
10
20
-10-20-30-40
0 5-5-5
0
5
10
10
15
-10
Rainfall change (%)
Po
ten
tia
l ev
apo
rati
on
ch
ang
e (
%)
<60
<70
<80
<90
<95
<100
<50
CumulativeProbability (%)
10Dam inflow change (%)
Atmospheric Research
Probabilities of flow changes - impacts view
Range of possible outcomes
0
10
20
30
40
50
60
70
80
90
100
-40-30-20-1001020
Change in supply (%)
Cu
mu
lativ
e P
rob
ab
ility
Burrendong Marshes Irrigation
Likeliest outcome
Atmospheric Research
Risk analysis resultsMacquarie 2030
0
10
20
30
40
50
60
70
80
90
100
-40-30-20-1001020
C ha nge in sup ply (% )
Cu
mu
lati
ve
Pro
ba
bili
ty
B urrend ong M arsh es Irr igat ion
DDR Nor mal FD R
Atmospheric Research
Characterising risk
The standard “7 step method” of impact assessment progresses from climate to impacts to adaptation. This infers that we must predict the likeliest climate before we can predict the likeliest impacts?
Agree or disagree?
Atmospheric Research
Characterising risk
There is another way.
Impacts = function(Gw)
Impacts = function(Gw,t,p)
p(impacts) = no. of scenarios < threshold = risk
Atmospheric Research
Risks to Many
Risks to Some
I
I Risks to unique and threatened systems
II
II Risks from extreme climate events
Large Increase
Increase
III Distribution of impacts
III
Negative for most regions
Negative for some regions
IV Aggregate impacts
IV
Net Negative
in all metrics
Markets + and -
Most people
worse off
V Risks from large-scale discontinuities
V
Very low
Higher
Characterising the risk of global warming
0ºC
1.4ºC
5.8ºC
Most likely
Least likely
Warming | Risk
Scenario 1
Scenario 5
Scenario 3Scenario 4
Scenario 6Scenario 2
Atmospheric Research
0 1 2 3 4 5
0
1
2
3
4
5
6
Glo
bal w
arm
ing
(°C
)
Frequency (%)
Increasing likelihood of global warming
0 50 100
0
1
2
3
4
5
6
Glo
bal w
arm
ing
(°C
)Frequency (%)
Pro
bab
ility
of t
hre
sho
ld
exc
eed
anc
e
Characterising the risk of global warming
Atmospheric Research
Characterising the risk of global warming
Risks to Many
Risks to Some
I
I Risks to unique and threatened systems
II
II Risks from extreme climate events
Large Increase
Increase
III Distribution of impacts
III
Negative for most regions
Negative for some regions
IV Aggregate impacts
IV
Net Negative
in all metrics
Markets + and -
Most people
worse off
V Risks from large-scale discontinuities
V
Very low
Higher
0 50 100
0
1
2
3
4
5
6
Glo
ba
l warm
ing (
°C)
Frequency (%)
Pro
bab
ility
of t
hre
sho
ld
exc
eed
anc
e
Atmospheric Research
Long-term planning Short-term policy response
1. Enhance adaptive capacity so that the current coping range expands, reducing present vulnerability.
2. Develop this capacity in such a way that the longer-term risks to climate change are also reduced.
Atmospheric Research
Basic principles
• Pay greater attention to recent climate experience. Link climate, impacts and outcomes to describe the coping range.
• Address adaptation to climate variability and extremes as part of reducing vulnerability to longer-term climate change.
• Assess risk according to how far climate change, in conjunction with other drivers of change, may drive activities beyond their coping range.
• Focus on present and future vulnerability to ground future adaptation policy development in present-day experience.
• Consider current development policies and proposed future activities and investments, especially those that may increase vulnerability.