Climate and Water

Can the water sector do anything with the

inherently uncertain climate change scenarios ? Prof. Dr. Pavel Kabat

Wageningen University and Research Center, NetherlandsEarth System Science & Climate Change Group www.ess.wur.nlClimate Centre (CCB) Wageningen UR www.wur.nl/ccb National Climate Change and Spatial Planning Research Programme of Netherlands www.climatechangesspatialplanning.nl

With thanks to:Prof. Mike Hulmes, Tyndall Centre, UKProf. Peter Cox, Exeter University & Hadley Centre, UKProf. Joseph Alcamo, Kassel University & UNEPProf. Kundzewich & IPCC 4AR colleagues

Worldwide Water Use by Region in km3 per year

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500

1000

1500

2000

2500

3000

3500

1900 1920 1940 1960 1980 2000 2020

EuropeNorth AmericaAfricaAsiaSouth AmericaAustralia& Pacific

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1900 1920 1940 1960 1980 2000 2020

Wa

ter

Use

in

km

^3

pe

r ye

ar

AgricultureIndustryHouseholdsReservoiresTotal

Worldwide Water Use by Sector

The current situation

1 billion people without access to safe drinking water

1.4 billion people in watersheds with < 1000m3/capita/year

2.4 billion people with poor sanitation

IPCC 2007

ALL WATER RELATED (WATER DEPENDENT)

SECTORS

Climate scenarios chain………..

Emissions

Narratives

Concentrations

Climate changeImpacts

So What are the Limits to Climate Prediction?

Uncertainties in climate prediction arise from:

Lack of knowledge (Epistemic uncertainty)

Parameter uncertainty

Structural uncertainty

Randomness (Natural stochastic uncertainty)

Initial conditions uncertainty

Human actions (Human reflexive uncertainty)

Cox and Stephenson, Science, 2007

Accuracy versus Precision

High accuracyLow precision

Low accuracyHigh precision

‘Global mean temperature will increase between 1.4º and 5.8ºC by

the end of the century’

‘Maximum temperature in July will increase by 3.7ºC in Marseille in

2088...

Accuracy versus Precision

Climate variable

e.g. 20th percentil

e

Precise, but inaccurate

‘True’ valueProbability density

‘Accurate’, but imprecise

Not if we understand the wider contexts in which adaptation has to take place ...

... spatial planning, technical regulation, economic priorities,adaptive management, risk management, cultural preferences, risk psychology …..

So is climate adaptation in the water sector therefore limited?

Are there Alternatives to Predict-and-Adapt?

Predict-then-adapt approach Assess-risk-of-policy framework

Structure Problem

Characterise Climate Uncertainty

Design Adaptation

Evaluate Outcome

Outcome Optimised for Climate

Structure Problem

Propose Various Strategies

Assess Strategies Against a Wide Range

of Qt/Ql Futures

Summarise Trade-Offs Among

Promising Strategies

Outcome Optimised for Robustness

Adaptation (autonomous

)

Adaptation (with

investments)

x1

Climate parameter (e.g. rainfall)

Fre

qu

ency

Extremen Extremen

Drought risk

Flood risk

“Acceptable risk”

“Acceptable risk”

Adaptation (autonomous

)

Adapation (with

investments)

x1

Climate parameter (e.g.rainfall)

Fre

qu

ency

P1P2

x2

Climate Change

“Acceptable risk”

So What are the Implications for Water Management?

• Water managers expect decisions to be based on the ‘best

possible’ (read precise) scenarios

• But the science of climate modelling is unlikely to fulfil the

expectations of decision-makers and, through over-

precision, could potentially lead to mal-adaptation if

misinterpreted or used incorrectly

• Water sector will benefit much more from a greater

understanding of the vulnerability of climate-influenced

decisions to large irreducible uncertainties and in the

context of a broader set of socio-economic drivers...

Conclusions

We argue that the epistemological limits to climate model

predictions should not be interpreted as a limit to adaptation in

water sector, despite the widespread belief that it is ...

…there is no magic bullet precise climate scenario, there will always

be scenario ranges, probabilities/ensembles and plausible or

less plausible futures….

Conclusions

….climate scenario selection and must go hand in hand with the

target application, and it should be accompanied by broader

vulnerability, risk and cost-benefit analysis…

….selected adaptation measure should be robust and flexible

enough to reflect scenario and uncertainty ranges….

... climate adaptation strategies in the water sector can therefore be

developed in the face of these uncertainties…

Case1: Netherlands: Climate proofing in water….

“The climate is changing and we should make our country climate proof. The national government together with science, policy and other stakeholders”

Jan-Peter Balkenende - DutchPrime Minister, november 2005” Science - Policy

interaction

Map The Netherlands

Flooding area 1953

Netherlands: Are there technological limits to adapt?

Sea level rise: “plausible high end scenarios”

2100: + 0.55 - 1.20 m (0.65 – 1.35 incl. soil subs.)

Key importance of adaptive management: adapataion measures must be flexible, no-regret (robust) and hand in hand with monitoring & ability to incorporate new scientific insifghts

28

Sea level rise scenarios

Plausible high end scenarios ( = not to be excluded given the current state of the art science) are needed to test how robust the adaptation mesures are ( specific to flood protection and water safety applications)

Vlieland, 9 november 2007Breskens, 9 november 2007Katwijk, 9 november 2007

Noordwijk, 9 november 2007

“Building with Nature”

Flexible regarding changing conditions and societal values, and increased understanding

Cost-effective Opportunities for

integrated and multifunctional approach

Case2: Thames Gateway

Thames Gateway: properties at risk (floodplain)

2007: 29%

2016: 71%

1879 Flood Act >

Late C19 update to Flood Act >

1928 Flood & subsequent 1930 Flood Act >

Interim Defences during the construction of the Thames Barrier >

The traditional solutionProgressive defence raising along the Thames

The Thames Estuary 2100 project:

• planning for the 21st century

• addresses extreme (plausible high end) climate change

scenario

• considers demographic and social change

• stakeholder involvement

• examines range of options

1m0m 4m3m2m

Max water level rise:

Existing system

New barrier, retain Thames Barrier, raise defences

Raise Defences

Improve Thames Barrier and raise d/s defences

Note:

Each box represents one or more portfolios of responses

The arrows indicate paths for adapting options for different sea level ranges

Flood storage, over rotate Thames Barrier, raise d/s defences

New barrier, raise defences

Flood storage, raise d/s defences

New barrage

Over-rotate Thames Barrier and raise d/s

defences

Route 1

Route 3a

Route 3b

Route 4

Route 2

Flood storage, improve Thames Barrier, raise u/s & d/s defences

1m0m 4m3m2m

Max water level rise:

New barrier, retain Thames Barrier, raise defences

Raise Defences

New barrier, raise defences

New barrage

2050 2100

Medium High Climate Change Scenario

Route 1

Route 3a

Route 3b

Route 4

Route 2

All four Routes suitable in 2100

Alternative Routes for achieving the plan

Existing system

Improve Thames Barrier and raise d/s defences

Over-rotate Thames Barrier and raise d/s

defencesFlood storage, improve Thames Barrier, raise u/s & d/s defences

Flood storage, over rotate Thames Barrier, raise d/s defences

Flood storage, raise d/s defences

Note:

Each box represents one or more portfolios of responses

The arrows indicate paths for adapting options for different sea level ranges

1m0m 4m3m2m

Max water level rise:

New barrier, retain Thames Barrier, raise defences

Raise Defences

New barrier, raise defences

New barrage

Route 1

Route 3a

Route 3b

Route 4

Route 2

High++ Climate Change Scenario

Only route 4 suitable in 2100

(unless SoP reduced)

21002050

The final plan could be a combination of options

Existing system

Improve Thames Barrier and raise d/s defences

Over-rotate Thames Barrier and restore interim defences

Flood storage, improve Thames Barrier, raise u/s & d/s defences

Flood storage, over rotate Thames Barrier, raise u/s & d/s defences

Flood storage, restore interim defences

Note:

Each box represents one or more portfolios of responses

The arrows indicate paths for adapting options for different sea level ranges

Case 3: Melbourne Water Management

mJohn Thwaites, Minister for Water 2002 - 2007

Public anger as Water Supply Plummets

Climate Change and Melbourne’s Water Supplies

Preliminary Estimates for Melbourne

(no climate change) (low climate change) Yield (medium climate change)

(high climate change)

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

1994

/95

1999

/00

2004

/05

2009

/10

2014

/15

2019

/20

2024

/25

2029

/30

2034

/35

2039

/40

2044

/45

2049

/50

2054

/55

Date

Megalitr

es

Yield

Demand

2034202420192016

Shortfall by 2055 of 178 billion litres

Example: Preliminary estimates for Melbourne

Water Supply Plummets 2006

Water Crisis 2006

Conservation: Melburnians are the best water savers in the

nation

Recycling

Melbourne 1999: 4% recycling

Melbourne 2005/06: 14% recycling

Melbourne Target: 20% by 2010

Our Water Our Future

Four key principles:

1. Conservation

2. Increased recycling and stormwater use

3. Boosting supplies

4. Looking after rivers

Impact of Conservation on Storage Level

500 GL/Year Average

37

0 G

L

38

1 G

L

41

0 G

L

44

7 G

L

44

3 G

L

47

9 G

L

43

9 G

L

DEMAND:

Recorded storage levels Projected storage levels without conservation

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10

20

30

40

50

60

70

80

90

100

July

/1996

July

/1997

July

/1998

July

/1999

July

/2000

July

/2001

July

/2002

July

/2003

July

/2004

July

/2005

July

/2006

July

/2007

July

/2008

July

/2009

July

/2010

Sto

rag

e v

olu

me

/ %

Lessons Learnt

With climate change it is difficult to predict water availability

Cannot rely on historic water data Climate Change impacts may be greater

than we thought

Positive Lessons Learnt: Conservation

2002 Strategy Target 12 % reduction per head by 2010

2006 Achieved 22 % reduction per head before strict

restrictions 2008

Achieved 36 % reduction per head more than the desalination plant supplies

Positive Lessons Learnt: Planning

A robust planning framework helped even if the predictions were wrong

Involved public early and changed attitude to water

Planning processes in place allowed adaptive management

Common alignment across water agencies and government

Thank you !