Slideshow Transcript

1. Slide 1: Tree rings and Prairie drought Scott St . George Geological Survey of Canada
2. Slide 2: How bad can Prairie drought get?
3. Slide 3: 100 years of stream and lake gauging
4. Slide 4: resource allocation
5. Slide 5: worst-case scenarios
6. Slide 9: 100 years of stream and lake gauging
7. Slide 10: not enough
8. Slide 12: How bad can Prairie drought get?
9. Slide 13: Prairie tree-ring network Northern Saskatchewan Eastern Rockies Northwestern Ontario Southern Manitoba
10. Slide 14: Regional tree growth and inferred summer climate in the Winnipeg River basin, Canada since AD 1783 Scott St. George David Meko Mike Evans in press, Quaternary Research
11. Slide 15: The tree-ring record of summer drought in the Canadian Prairies Scott St. George David Meko Greg Pederson Martin-Phillippe Girardin David Sauchyn Glen MacDonald Jacques Tardif Erik Nielsen Emma Watson Submitted to the Journal of Climate, January 2008
12. Slide 16: 3 Seasonality Accuracy Drought history
13. Slide 17: Seasonality
14. Slide 18: Prairie tree-ring network Northern Saskatchewan Eastern Rockies Northwestern Ontario Southern Manitoba
15. Slide 19: Prairie trees principally track summer precipitation 90 82 Number of sites 75 60 45 30 24 15 7 3 0 19 Autumn Winter Spring Summer Autumn
16. Slide 20: 20
17. Slide 21: Vaganov-Shashkin model of tree-ring formation Gr(t) = g E (t) • min[g T (t), g W (t)] Total Solar radiation Temperature Water balance growth rate growth rate growth rate growth rate
18. Slide 22: INPUT Daily climate data MODEL Vaganov-Shashkin model Synthetic OUT Daily growth rates Cell characteristics ringwidth chronologies
19. Slide 23: INPUT Daily climate data MODEL Vaganov-Shashkin model Synthetic OUT Daily growth rates Cell characteristics ringwidth chronologies
20. Slide 24: Medicine Hat, Alberta Source: Environment Canada, Adjusted Historical Canadian Climate Data, 1895 – 2006
21. Slide 25: 25
22. Slide 26: 26
23. Slide 28: El Niño (1983)
24. Slide 29: ENSO and winter ppt Correlation between CTI and winter precipitation (● = significant at p = 0.05)
25. Slide 30: ENSO and PDSI Correlation between CTI and summer PDSI (● = significant at p = 0.05)
26. Slide 31: Prairie ringwidth records 138 Significant correlation with ENSO 4 Expected from random chance 6.9 31
27. Slide 32: 32
28. Slide 34: Accuracy
29. Slide 35: “ This must be voodoo.” Anonymous water manager
30. Slide 36: How good are drought records from tree rings?
31. Slide 37: Ringwidth as a proxy for ‘Lethbridge’ PDSI
32. Slide 38: 755 m3/s 847 m3/s 809 m3/s 770 m3/s 823 m3/s 787 m3/s 901 m3/s 3
33. Slide 39: Error of the estimate
34. Slide 40: Error of the estimate
35. Slide 41: 755 m3/s 847 m3/s 809 m3/s 770 m3/s 823 m3/s 787 m3/s 901 m3/s 3
36. Slide 42: Very wet Wet Average Dry Very dry
37. Slide 44: Drought history
38. Slide 45: Prairie tree-ring network Northern Saskatchewan Eastern Rockies Northwestern Ontario Southern Manitoba
39. Slide 46: Eastern Rockies drought
40. Slide 47: 1720s
41. Slide 48: 58 oN 56 oN 1718 - 1722 54 oN 52 oN 50 oN 48 oN oW 90 114 oW 9 6o W 108oW 10 2oW Ringwidth anomaly −2 -2 −1 0 0 1 2 +2 (deviations)
42. Slide 49: 49
43. Slide 51: La Niña (1989)
44. Slide 52: ENSO and PDSI Correlation between CTI and summer PDSI (● = significant at p = 0.05)
45. Slide 54: 3 main points
46. Slide 55: Prairie trees record summer drought
47. Slide 56: Pacific Ocean influences are weak
48. Slide 57: How bad can Prairie drought get?
49. Slide 58: worse
50. Slide 59: Tree rings and Prairie drought web.mac.com/scottstgeorge