Status and Change of Climate Change Scenarios: Has Uncertainty Decreased?...and What to Do About It

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1 Status and Change of Climate Change Scenarios: Has Uncertainty Decreased?...and What to Do About It Paul Fleming Climate Resiliency Group Seattle Public Utilities 1

2 overview uncertainty prayer key concepts utilities use of and interest in climate projections uncertainty in climate projections strategies to address uncertainty conclusions 2

3 The Uncertainty Prayer Grant us. The ability to reduce the uncertainties we can; The willingness to work with the certainties we cannot; And the scientific knowledge to know the difference 3

4 key concepts Death of Stationarity natural systems fluctuate basis for water resource management no longer valid End of Reliability end of static design paradigm limited utility of GCM output 4

5 water utility use of climate projections eagerness to assess impacts on water systems increased use of climate projections often fed into chain of models (GCM + hydrology + system models) can lead to cascading uncertainties 5

6 impacts in Seattle 6

7 uncertain impacts in Seattle 7

8 Water Utility Climate Alliance Portland Water Bureau Seattle Public Utilities San Francisc o Public Utilities Commission Metropolitan Water District of So. California Southern Nevada Water Authority (Vice Chair) San Diego County Water Authority Denver Water Central Arizona Project New York City Department of Environmental Protection Tampa Bay Water (Chair) Mission: The Water Utility Climate Alliances provides leadership in assessing and adapting to the potential effects of climate change through collaborative action. We seek to enhance the usefulness of climate science for the adaptation community and improve water management decision-making in the face of climate uncertainty. 8 Slide created by David Behar, SFPUC

9 climate modeling and managing uncertainty Options for Improving Climate Modeling to Assist Water Utility Planning for Climate Change Decision Support Planning Methods: Incorporating Climate Change Uncertainties into Water Planning available at 9

10 improving the usefulness of climate projections Options for Improving Climate Modeling to Assist Water Utility Planning for Climate Change model agreement on change in key parameters narrowing of the range of model output temporal and spatial resolutions improved projections within planning horizons available at 10

11 improving the usefulness of climate projections Options for Improving Climate Modeling to Assist Water Utility Planning for Climate Change expectation of increased confidence and utility sizeable improvement > 10yrs + need for continued dialogue management approaches essential given uncertainty available at 11

12 actionable science Actionable science provides data, analyses, projections, or approaches that can support assessment or management of the risks and impacts of climate change. It is ideally co-produced by scientists and decision-makers working together, and creates rigorous, understandable, accessible and usable products to meet the needs of all stakeholders. 12

13 sources of uncertainty future emissions natural variability model approximation climate sensitivity have to pay attention to types of question being asked: spatial and temporal scales variables of interest Claudia Tebaldi, PUMA Workshop, Dec

14 CMIP5 next generation of climate data basis of IPCC 5 th AR impacts community starting to utilize data how much better is it than CMIP3? has uncertainty decreased? 14

15 CMIP5 next generation of climate data temperature improvement large patterns of precip somewhat improved regional level precip not simulated as well substantial progress in extremes high confidence that regional downscaling adds value IPCC AR5 WG1 Report, Ch. 9 15

16 CMIP5 Performance IPCC AR5 WG1 Report, Ch 9, 2013 Prepared enabling change Aarhus, 21 23, January 2014

17 CMIP5 Next Generation of Climate Data model spread has not changed much unknown unknowns better incorporated more confident that relevant processes are captured impact relevant predictions may be even harder to improve too limiting to define progress in terms of limiting uncertainty? Knutti and Sedlacek,

18 ranking model performance established metrics to compare 37 GCMs against observations in PNW ranked performance or credibility noted few differences btwn CMIP3 and CMIP5 Rupp et al, in review 18

19 making science more actionable identify which parameters are better modeled in a given region bottom up approaches with those parameters weighting models greater emphasis on model interpreters and translators continued dialogue and co-production with climate modelers and users ( users as shapers of research) 19

20 management responses to uncertainty decision analysis real options scenario planning robust decision making portfolio planning Attributes: dynamic, incremental, adaptive, flexible, choices that aren t sensitive to uncertainty Means et al,

21 scenario planning plausible descriptions of the future not predictions alternate potential circumstances w/o probability focused on surfacing uncertainties develop signposts Means et al,

22 robust decision making combines decision analysis with scenario planning relies on simulation models robust vs optimized evaluates numerous strategies over many possible futures involves hedging Rob Lempert at Rand leading practitioner Making Good Decisions Without Predictions, Rand Corporation 22

23 real options pioneered by WSAA combines decision analysis with financial theory options analysis incremental and adaptive decision making monitoring Means et al,

24 portfolio planning combination of assets and strategies diversification lazy assets identify: return risk/volatility of return contribution of each element Means et al,

25 conclusions climate change poses science, management and policy challenges undercuts key assumptions and strategies calls for utility engagement and innovation engage researchers, articulate our needs reduce uncertainties we can refine our management approaches: dynamic flexible adaptive 25

26 Acknowledgements Claudia Tebaldi, NCAR/Climate Central Phil Mote, Oregon State University Jeff Arnold, US Army Corps of Engineers Rob Lempert, Rand Joel Smith, Stratus Consulting My colleagues in WUCA 26

27 Thank You Aarhus, 21 23, January 2014 Prepared enabling change 27