1. Recent Climate Change Modeling Results
Eric Salathé Climate Impacts Group University of Washington

2. Global Climate Models 20th Century Validation

3. IPCC Scenarios for Pacific Northwest Climate Change

4. Range of Projected Climate Change for the Pacific Northwest from Latest IPCC Climate Simulations

7. 21st Century Change

8. Shift in Pacific Storm Track
Observed
20th Century Model Composite
21st Century Model Composite
Salathé, Geophys Res Lett, 2006

9. Downscaling

10. Downscaling Methods Used in CIG Impacts studies
Empirical Downscaling
• Assumes climate model captures temperature and precipitation trends
• Quick: Can do many scenarios
• Shares uncertainties with global models
Regional Climate Model
Based on MM5 regional weather model
Represents regional weather processes
May produce local trends not depicted by global models
Additional modeling layer adds bias and uncertainty

11. Mesoscale Climate Model
Based on MM5 Weather Model
Nested grids km
Nudging on outermost grid by forcing global model
Advanced land-surface model (NOAH) with interactive deep soil temperature

12. Potential Surprises
How does loss of snowpack feed back on the climate?
How do changes in the winds affect the local climate?
Are their changes in cloudiness that can affect the local rate of warming?

13. MM5 Simulations ECHAM5 global model to force the mesoscale system
to see how well the system is working
, , Climate Change

14. 1990s Validation 1995 Daily Max and Min Temperature at SeaTac
MM5 Max
Obs Record Max
Obs Mean Max
Temperature (°F)
Obs Mean Min
Obs Record Min
MM5 Min
Day of Year

15. 1990s Validation 1990-2000 Mean Surface temperature January July
Gridded Observations
MM5 - NCEP Reanalysis
MM5 - ECHAM5
January
July

16. Evaluation of Future Runs
Because there are some biases in the GCM runs, results for future decades (2020s, 2040s, and 2090s) will be evaluated against the ECHAM5-MM baseline

17. Difference between MM5 and ECHAM5
Winter Warming
1990s to 2050s
Temperature Change
Difference between MM5 and ECHAM5

18. Loss of Snow cover and Warming
Snow Cover Change
Temperature Change

19. Consistent trend over 21st Century

20. MM5 Compared to raw Climate model
2020s
2050s
2090s

21. Difference between MM5 and ECHAM5
Spring
1990s to 2050s
Temperature Change
Difference between MM5 and ECHAM5

22. Pressure gradient and Cloud
Pressure Change
Cloud Change

23. Trend over 21st Century
2020s
2050s
2090s

24. MM5 Compared to Raw Climate Model
2020s
2050s
2090s

25. Winter Trends at Various Stations
MM5 - ECHAM5
10 IPCC Models

26. Applications: Air Quality

27. Applications: Hydrology

28. Summary Projected Pacific Northwest Climate Change
warming: 1/4 to 1 ºF/decade
Probably more warming in Summer than Winter
Precipitation changes uncertain – Possibly wetter winters and drier summers
Challenges
Deficiencies in Global model propagate to regional model
Biases from regional model
Mesoscale model simulates different climate signal from global model
Loss of snow amplifies warming in Winter and Spring
Increased cloud cover in Spring -- reduces effect of snow loss

29. Shift to Northerly Winds
Change in Sea-level Pressure
Change in Surface Winds