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, Netherlands Earth System Science & Climate Change Group Climate Centre (CCB) Wageningen UR National Climate Change and Spatial Planning Research Programme of Netherlands With thanks to: Prof. Mike Hulmes, Tyndall Centre, UK Prof. Peter Cox, Exeter University & Hadley Centre, UK Prof. Joseph Alcamo, Kassel University & UNEP Prof. Kundzewich & IPCC 4AR colleagues

Worldwide Water Use by Region in km 3 per year

Worldwide Water Use by Sector

The current situation 1 billion people without access to safe drinking water 1.4 billion people in watersheds with < 1000m 3 /capita/year 2.4 billion people with poor sanitation

IPCC 2007 ALL WATER RELATED (WATER DEPENDENT) SECTORS

Climate scenarios chain……….. EmissionsNarratives 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 accuracy Low precision Low accuracy High 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

Accuracy versus Precision Climate variable e.g. 20th percentil e Precise, but inaccurate ‘True’ value Probability 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 approachAssess-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) x1x1 Climate parameter (e.g. rainfall) Frequency Extremen Drought risk Flood risk “Acceptable risk”

Adaptation (autonomous) Adapation (with investments) x1x1 Climate parameter (e.g.rainfall) Frequency P1P1 P2P2 x2x2 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 - Dutch Prime 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: 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 2007 Breskens, 9 november 2007 Katwijk, 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 solution Progressive defence raising along the Thames

The Thames Estuary 2100 project: planning for the 21 st century addresses extreme (plausible high end) climate change scenario considers demographic and social change stakeholder involvement examines range of options

1m 0m 4m 3m 2m 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

1m 0m 4m 3m 2m Max water level rise: New barrier, retain Thames Barrier, raise defences Raise Defences New barrier, raise defences New barrage 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 defences Flood 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

1m 0m 4m 3m 2m 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) 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 m John Thwaites, Minister for Water

Public anger as Water Supply Plummets

Climate Change and Melbourne’s Water Supplies Preliminary Estimates for Melbourne 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

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 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 !