1. Best practice in using climate scenarios and hydrological models Rob Wilby, Department of Geography, Loughborough University (r.l.wilby@lboro.ac.uk)r.l.wilby@lboro.ac.uk PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan Model simulations of annual energy production at Kairakkum, Tajikistan

2. Changing mix of uncertainty elements The total uncertainty in CMIP3 global mean, decadal mean projections for the 21st century, separated into three components: internal variability (orange), model uncertainty (blue) and scenario uncertainty (green). Source: Hawkins and Sutton (2010) PrecipitationTemperature PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

3. PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan Future society GHG emissions Climate model Regional scenario Impact model Local impacts Adaptation responses Envelope of uncertainty The cascade of uncertainty Source: Wilby & Dessai (2009) Cascading uncertainties

4. Three big assumptions: 1.Skill at simulating the present climate implies skill at predicting the future climate 2.Agreement amongst climate models boosts confidence in predictions 3.All known regional climate forcings are included in the climate prediction Winter temperatures (four GCMs) Winter temperature bias (four GCMs) CMIP3 average Source: Knutti (2008) Hard truths

5. PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan Is there another way?

6. Strategy 0: Conventional scenario-led Climate change flow factors (2020s) for the River Itchen at Highbridge. Data source: UKWIR (2007) PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

7. Strategy 1: Demand management PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

8. Mean annual frequency of ecologically harmful flows (<224 Ml/d) in the River Itchen under various abstraction license conditions, climate variability and change. Source: Wilby et al. (2011). Strategy 2: Modify operations PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

9. Strategy 3: Delay decision/investment Detection times (years from 1990) for summer low flows in the River Itchen using two different periods to estimate variance (1961-90 and 1921-90). Source: Wilby (2006) PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

10. Strategy 4: Accept lower levels of performance The business as usual scenario for East Devon: the fraction of CP.net projections that fail to meet average water demand in October under SRES A1B. Source: Lopez et al (2009) PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

11. Modelled water supply failure rates (%) in East Devon, UK with no adaptation to climate change (Business as Usual), 15% reduction in water consumption (Demand), 18% increase in storage capacity (Reservoir), or demand reduction combined with increased storage (Demand+Reservoir). The results are based on 246 climate model runs under SRES A1B emissions from the CPDN experiment. Without adaptation the system failure rate exceeds 35% by the 2070s, but with both demand reduction and increased reservoir capacity is less than 10%. Source: Lopez et al (2009). Strategy 5: Evaluate adaptation portfolios PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

12. Strategy 6: Improve asset/network resilience Source: Henriques & Spraggs (2011) *Security & Emergency Measures Direction * Resistance to +20% flood Resilience to +20% flood PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

13. Strategy 7: Apply safety margin(s) PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan

14. Concluding remarks Climate models best used for sensitivity tests Plenty of low regret measures (hydrometry) Seasonal forecasting more tractable System models useful for evaluating options PPCR Workshop on Climate Resilience and the Energy Sector 6-7 March 2012, Barki Tojik, Dushanbe, Tajikistan