atmospheric research climate hazards & risk assessment roger n. jones aiacc kickoff meeting...

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.