1. Developing Tools to Enable Water Resource Managers to Plan for & Adapt to Climate Change Amy Snover, PhD Climate Impacts Group University of Washington July 2, 2004 SICCIA Climate Science in the Public Interest

2. Introduction Despite uncertainties in climate change projections –PNW water resources clearly vulnerable over next few decades –Many PNW water resources managers now recognize importance of planning for climate change Academic climate change impact assessments tend to be “interesting but irrelevant” to resource managers Need for future streamflow scenarios that could be easily and inexpensively used within existing planning frameworks Academic Research Resource Management ??

3. ~ + 1.7 C ~ + 2.5 C Somewhat wetter winters and perhaps somewhat drier summers Projected PNW Climate Change

4. Main Impact: Less Snow Snow-dominated Rain + Snow

5. Sensitivity of Water Resources PNW water systems relatively little reservoir storage strong reliance on mountain snowpack  sensitive to changes in the seasonal pattern of streamflows Timing of significant changes: ~20 years: hydrologic changes in rain/snow watersheds 40-50 years: hydrologic changes in snow-melt dominated systems Decades required to change water resources infrastructure or policy  PNW policy makers and water management agencies need to start planning for potential climate change now

6. 1997-2001: Increasingly focused climate change research Intensive region-wide outreach Widespread official recognition of regional water resources systems’ lack of capacity to meet present & anticipated future demands even without climate change! Planning for climate change 1997: First examination of PNW climate change impacts. Most stakeholders unfamiliar with potential impacts of climate change unprepared to use information Out in Front: Portland & Seattle Evaluating long-range planning alternatives under 5 different climate change scenarios (both supply & demand-side impacts) 1995: Interviews with natural resource managers Little recognition of predictability of climate No framework for applying information about climate change

7. Stakeholders requested: Climate change information for use in existing planning models Case studies of incorporating climate change projections into basin planning Planning for climate change 2001 High level water policy workshop: Climate change = potentially significant threat to regional water resources Climate change information = critical to future planning Significant step forward! Requirements of climate change information: more detailed, small scale information (catchment, watershed) must be “easy to apply to the problem at hand”

8. Observed Streamflows Planning Models System Drivers Critical Period Planning Methods for Water Studies Long-Range Water Resources Planning How would the water resources system respond to the drought of the 1930s with the current/alternate reservoir operating policy?

9. Observed Streamflows Climate Change Scenarios Planning Models Altered Streamflows System Drivers Incorporating Climate Change in Critical Period Planning What would water year X mean for our water resources system if the average climate changed as projected?

10. Climate change streamflow scenario development Four GCM climate change scenarios (2020s & 2040s) Downscaled to PNW using “delta method” –Perturb gridded historical meteorological data by monthly projected ∆T and ∆p –Retains fundamental temporal and spatial variability of observed regional climate and chronological sequencing of observed flows Simulate 40 year time series of monthly streamflows using hydrologic model Remove hydrologic model bias via probability mapping

11. Distributed hydrology model (VIC) Monthly changes in mean temperature and precipitation from global climate models Observed time series of meteorological data (gridded) Removal of hydrologic model bias using probability mapping Climate change streamflow scenarios

12. Application of Scenarios Tailored for use by –Northwest Power Planning Council (regional hydropower resources) –Idaho Department of Water Resources (irrigation) Publicly available via web server Portable method can be applied to other users

13. Planning for Climate Change: Future streamflow scenarios Water policy workshops have highlighted the need to inject climate change information into existing river basin planning activities and to provide free access to streamflow scenarios. www.cses.washington.edu/cig/www.cses.washington.edu/cig/ … see “Forecasts and Planning Tools”Snover et al. BAMS 2003

14. Conclusions Despite uncertainty in climate change projections, PNW water resources likely to experience important impacts within a few decades Initial outreach efforts (“describing & exhorting”) had some success –Potential impacts are well recognized –Shift in dialogue from what will happen to how to plan for it Without additional effort by academics to develop useful tools, region not likely to progress beyond a cursory examination of climate change Climate change streamflow scenarios (produced by perturbing the observed historical streamflow record) can be easily and inexpensively used in existing planning processes –Intent is to enable rapid injection of climate change information to support vulnerability assessment –First step towards more sophisticated assessments –Provides a “road map” for other agencies

15. For More Information … UW Climate Impacts Groupwww.cses.washington.edu Climate Science in the Public Interest