Tree rings and drought on the Canadian Prairies

Slide 1: Tree Rings and Drought Past drought on the Canadian Prairies S co tt St. Ge orge Geological Survey of Canada

Slide 2: Prairie tree-ring network, ca. 1996

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Slide 5: Fort Dufferin, Manitoba

Slide 6: 4,000 year-old river logs 6

Slide 7: Prairie tree-ring network Northern Saskatchewan Eastern Rockies Northwestern Ontario Southern Manitoba

Slide 8: 4 Characteristics of Prairie tree rings

Slide 9: 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

Slide 10: Tree age

Slide 11: Bristlecone pine 4,844 years Source: OLDLIST Photo: Tom Harlan

Slide 12: Eastern white cedar 1,653 years Source: OLDLIST Photo: Peter Kelly

Slide 13: Eastern white pine 290 years Source: M. Girardin

Slide 14: Bur oak 279 years

Slide 15: Limber pine 846 years Source: G. Pederson Photo: Greg Pederson

Slide 16: Richard I of England 16 Photo: julie & fanu

Slide 17: Length of regional records S. Alberta 480 N. Saskatchewan 169 S. Manitoba 485 NW Ontario 225 0 125 250 375 500 Years

Slide 18: Seasonality

Slide 19: “ The trees composing the forest rejoice and lament with its successes and failures and carry year by year something of its story in their annual rings. ”Douglass A.E.

Slide 20: Dominant seasonal signals 90 82 80 70 60 50 Sites 40 30 24 20 10 7 3 0 20 Autumn Winter Spring Summer Autumn

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Slide 23: Medicine Hat, Alberta Source: Environment Canada, Adjusted Historical Canadian Climate Data, 1895 – 2006

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Slide 25: Effectiveness

Slide 26: Dendrohydrology works best where it’s dry ...

Slide 27: and not so well where it’s wet

Slide 28: Ringwidth as a proxy for ‘Lethbridge’ PDSI

Slide 29: Ringwidth as a proxy for ‘Dryden’ PDSI

Slide 30: Uncertainty

Slide 31: 755 m3/s 847 m3/s 809 m3/s 770 m3/s 823 m3/s 787 m3/s 901 m3/s 3

Slide 32: “Trees are not thermometers or raingauges.” Keith Briffa and colleagues

Slide 33: Quantitative drought estimates

Slide 34: Quantitative drought estimates

Slide 35: Can we Absolutely! do better?

Slide 36: Photo: Emma Watson

Slide 38: Photo: New York Times 38

Slide 39: Focus on long-term drought 100% 60% 43% Explained variance 75% 50% 57% 40% 25% 0% Single Year 5-Year Average

Slide 40: Courtesy Keith Lombardo Measure other stuff Wood chemistry Wood density Stable isotopes Wood anatomy

Slide 41: Prairie tree rings & drought 41

Slide 42: Photo: Monceau web.mac.com/scottstgeorge