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Pacific Northwest National Laboratory U.S. Department of Energy The Effects Of Climate Change On Water Resources In The Western United States: The Accelerated.

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Presentation on theme: "Pacific Northwest National Laboratory U.S. Department of Energy The Effects Of Climate Change On Water Resources In The Western United States: The Accelerated."— Presentation transcript:

1 Pacific Northwest National Laboratory U.S. Department of Energy The Effects Of Climate Change On Water Resources In The Western United States: The Accelerated Climate Prediction Initiative Bill Pennell, Pacific Northwest National Laboratory Tim Barnett, Scripps Institution of Oceanography April 30, 2003

2 2 The ACPI Demonstration Project

3 3 Implementation Ocean Data Assimilation: UCSD, NPS Global Climate Modeling: NCAR/LANL PCM Downscaling: PNNL & UCSD Impacts: Columbia River: UW Yakima River: PNNL Sacramento/San Joaquin Rivers: UW, UCSD, USGS, PNNL Wild fires: UCSD & DRI Ocean Data Assimilation Global Climate Modeling Downscaling Impact Assessment

4 4 Step 1 Begin with current state of global oceans

5 5 Why Initialize the Oceans? That’s where the heat has gone! Data from Levitus et al, Science, 2001

6 6

7 7 How Good is the Ocean Simulation? Pierce et al, Climatic Change, to appear

8 8 Step 2 Estimate climate change due to emissions

9 9 Global Climate Change Simulations Used NCAR/DOE Parallel Climate Model (PCM) Three projections using the Business as Usual Scenario (BAU) Period covered: 1860-2100 These simulations provided the basis for our projections of western U.S. climate change

10 10 How well does the PCM work over the Western United States? Dec-Jan-Feb total precipitation (cm)

11 11 Projected change by 2050

12 12 Step 3 Downscaling and Impacts

13 13 Why do we do it? Global model (orange dots) vs. Regional model grid (green dots)

14 14 It works El Nino rainfall simulation ObservationsDownscaled modelStandard reanalysis Ruby Leung, PNNL

15 15 And It Clearly Improves PCM Simulations PCMRCM Absolute Bias (mm/day) Winter (DJF) Summer (JJA) Control Simulation Precipitation Biases

16 16 Precipitation Skill Score PCM RCM 0 0.1 0.2 0.3 0.4 0.5 123456789101112 0 0.1 0.2 0.3 0.4 0.5 123456789101112 0 0.1 0.2 0.3 0.4 0.5 123456789101112 0 0.1 0.2 0.3 0.4 0.5 123456789101112 Equitable Threat Score Precipitation Threshold (mm/day) Columbia River BasinSacramento-San Joaquin Basin

17 17 So What Does the “Future” Look Like? An Ensemble of Projected Future Climate Simulated by the PCM

18 18 TemperaturePrecipitation PCM RCM Climate Change Signals (2040-2060)

19 19 Extreme Precipitation and Snowpack Changes

20 20 Such Changes Would Clearly Affect Water Resources Andrew Wood, Univ. of Washington

21 21 And The Effects Would be Greater for Smaller River Basins Source: Lance Vail, PNNL

22 22 ClimateMean flow (m3/s) Peak flow (m3/s) Peak flow date 1/3 date1/2 dateFreshet date Historic48.2281May 17Mar 11May 1May 16 BAU4452.0285Jan 25Jan 24Mar 14 BAU4652.0270Feb 4Feb 5Mar 20Apr 8 BAU4754.9262Mar 18Feb 17Mar 25Apr 21 Average altered climate change from historic 4.8-9-91-34-42 Streamflow and snowmelt statistics for regulated basins. Values are medians computed from 19 years of model output for each climate. Difference in dates is given in days. Source: Lance Vail, PNNL

23 23 With Consequences for Humans ScenarioBase20% Increase In Demand 20% Decrease In Demand 20% Increase In Storage 20% Decrease In Storage Current Climate 560211 BAU 447152217 BAU 469123314 BAU 473120116 Number of years (out of 19) with prorationing reductions greater than 25% of normal flow for current climate and for 3 BAU realizations. System forecast and operation rules based on current climate data. Note: Prorationing means reductions to users with junior water rights. Reductions greater than 25% have significant economic impacts. Source: Lance Vail, PNNL

24 24 ScenarioBase20% Increase In Demand 20% Decrease In Demand 20% Increase In Storage 20% Decrease In Storage Current Climate 66304020695 BAU 44384928891601704 BAU 4639689729501396 BAU 47119480051330 Total number of days (out of 19 years) with prorationing reductions greater than 25% of normal flow for current climate and for 3 BAU realizations. Normal irrigation season in the Yakima Basin runs from April through September or about 180 days. Source: Lance Vail, PNNL

25 25 And Fish Warm Fall WaterEarlier Freshet Spawning, Incubation, Rearing, Smolt Migration Historical Climate Altered Climate Climate Change will Seriously Compress the Time Available for Fall Chinook to Complete their Spawning Cycle


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