ABSOLUTE HISTORY THE STORY OF TREE RINGS

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ABSOLUTE HISTORY THE STORY OF TREE RINGS
CLIMATE IN THE SOUTHWEST

• Dr. Katie HirschboeckLaboratory of Tree-Ring
  ResearchUniversity of ArizonaWestern Snow
  Conference2003

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What we take for the history of nature is only
the very incomplete history of an instant
--Denis Diderot
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ABSOLUTE HISTORY

• ABSOLUTE (def) relating to or derived in the
  simplest manner from the fundamental units of
  length, mass, and time
• HISTORY (def)
• a branch of knowledge that records and explains
  past events

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OUTLINE

• A BRIEF HISTORY OF TREE RINGS
• DENDROCHRONOLGY, ARCHAEOLOGY DROUGHT
• STUDIES IN CLIMATE, FIRE, WATER . . . . SNOW

Acknowledgments The Laboratory of Tree-Ring
Research (LTRR), Dr. Tom Swetnam (Director), Dr.
Connie Woodhouse, and countless other LTRR
researchers
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What happened to the Anasazi? Why did they leave
and where did they go?
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Are we less vulnerable today to droughts and
other climate-related disasters than the Anasazi,
or Great Plains farmers of the 1930s?
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A BRIEF HISTORYOF TREE RINGS
Andrew Ellicott Douglass 1867-1962 Founder of
Modern Dendrochronology The Laboratory of
Tree-Ring Research
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REPLICATION noise minimized by sampling many
trees at a site more than one core per tree
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ABSOLUTE DATING matching the patterns in ring
widths of several tree-ring series of known age
allows precise dating to the exact year
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Crossdating The Basic Principle of
Dendrochronology
B
A
C
Bridging back in time
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DENDROCHRONOLOGY, ARCHAEOLOGY DROUGHT
CHACO CANYON, N.M.
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The search for tree rings that would bridge the
gap between living trees and the beams in
abandoned cliff dwellings included the sampling
of beams in Hopi villages.
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Stuck in the mud! National Geographic Society
sponsored Beam Expeditions 1920s
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Excavating specimen HH-39, which bridged the
gap Show Low, Arizona, July 22, 1929
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Secrets of the Southwest Solved by Talkative
Tree Rings, by A. E. Douglass, National
Geographic Magazine, December 1929
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Population estimates from tree-ring dated
dwellings indicate nearly total abandonment of
the Colorado Plateau by AD 1300, while a major
influx of people occurred in northern New Mexico
at this time.
From Dean, Doelle, Orcutt 1994
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SOURCE Swetnam Betancourt, 1998 Journal of
Climate
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STUDIES IN CLIMATE, FIRE, WATER . . .
. . . SNOW
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DENDROCLIMATOLOGY
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Complacent Sensitive
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Tree-ring width chronologies from dry sites are
highly correlated with precipitation patterns.
Statistical models are used to calibrate the
tree-ring chronologies in terms of precipitation
units . . .
SOURCE Fenbiao Ni, Tereza Cavazos, Malcolm K.
Hughes, Andrew C. Comrie, and Gary Funkhouser
2002. International Journal of Climatology.
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. . . Or drought indices
Palmer Drought Severity Index(PDSI)
reconstructed for the Southwest (4 corners
states)
Source Sheppard et al. (2002) The Climate of
the Southwest Climate Res.
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Long-term Variability of Southwest PDSI
Source CLIMAS, U of AZ website(Climate of the
Southwest link -- based on Sheppard et al., 2000)
http//www.ispe.arizona.edu/climas/learning.html
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FIRE HISTORY FROM TREE RINGS
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FIRE HISTORY DROUGHT
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Fire-scar chronology from Santa Catalina
Mountains, Arizona
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Cerro Grande Fire Los Alamos, NM
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DENDROHYDROLOGY
STREAMFLOWRECONSTRUCTIONS
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PHYSICAL BASIS FOR DENDROHYDROLOGY
EVAPO-TRANSPIRATION
Based on Meko, et al., 1995
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Stockton, C.W., 1975Stockton Jacoby, 1976
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Colorado River at Lees FerryReconstructed Runoff
Stockton, 1975Stockton Jacoby, 1976
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Tree-Ring / Water Resource Management
PartnershipsDr. Connie Woodhouse NOAA
Paleoclimatology Program, National Climatic Data
Center, Boulder, CO
How does the Front Range drought of 2002 compare
to other low flow extremes?
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Data and figure from Connie Woodhouse, NOAA
Paleoclimatology Program
The severity of 2002 has been matched or exceeded
4-6 times in the past 315 years and 8-10 times in
the past 560 years.
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Data and figure from Connie Woodhouse, NOAA
When considered as a 3-year drought, the period
2000-2002 is a much rarer event.
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A 431-Year Reconstruction of Western Colorado
Snowpack from Tree Rings
Forthcoming Woodhouse, C. Journal of Climate,
15 May 2003
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SOME FINAL REFLECTIONSABSOLUTE HISTORYThe
Story of Tree Rings Climate in the Southwest
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Every time history repeats itself, the price
goes up. -- John A. Appleman
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Life must be lived forward, but understood
backward -- Kierkegaard
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