1. SURFACE TEMPERATURE
RECONSTRUCTIONS
FOR T H E LAS T 2 , 00 0 Y E A R S
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES

4. Photograph: Nevada Tourism Media Relations

5. Tucson

6. Photograph: Chazz Lane
Central Arizona Project

9. Photograph: Ben Amstutz

10. Photograph: Ben Amstutz

11. Photograph: Michael Koukoullis

12. Water transfers in the American southwest
Courtesy Glen MacDonald

13. Colorado River Compact
1922

14. Average river flow, 1906 to 1922
18 MAF

15. allocated to 7 basin states
15 MAF
Average river flow, 1906 to 1922
18 MAF

16. allocated to Mexico
1½ MAF
allocated to 7 basin states
15 MAF
Average river flow, 1906 to 1922
18 MAF

18. Observed discharge, Colorado River
Compact allocation (16.5 MAF)

19. Observed discharge, Colorado River
Compact allocation (16.5 MAF)

20. Average river flow, 1906 to 2005
15 MAF

21. Average river flow, 1906 to 2005
15 MAF

22. UNITED STATES MEXICO
Arizona Sonora
California Baja California
Colorado
New Mexico
Nevada
Utah
Wyoming

23. Low reservoir
Photograph: Glen MacDonald

25. T H E W E S T, WA T E R A N D T H E C O L O R A D O R I V E R

27. Tree-ring display at elementary school
Photograph:Tom Swetnam

29. The history of precipitation and
runoff in the Colorado Basin as
indicated by tree-rings
Edmund Shulman
Ph.D. Thesis
Harvard University
1944

33. water stress
narrow ring reduced photosynthesis
less cell expansion
reduced cell division

34. INDIRECT
RELATION

37. Source: Woodhouse et al., 2006

38. 100%
EXPLAINED VARIANCE
St. George and Luckman
JJA temperature
0%

39. 100%
EXPLAINED VARIANCE
Woodhouse et al.
Annual discharge
St. George and Luckman
JJA temperature
0%

40. stream gauge
tree-ring estimate
Source: Woodhouse et al., 2006

41. Source: Woodhouse et al., 2006

42. MEGADROUGHT
intensity at least equivalent to modern multiyear droughts
duration longer than the several years to decade thereof
Seager et al., Journal of Climate, 2008

43. “ Average reconstructed annual flow
for the period 1844–1848 was lower
”
than the observed flow for 1999–2004.
Woodhouse et al., 2006

44. “ The long-term perspective provided by
tree ring reconstructions points to looming
conflict between water demand and supply
”
in the upper Colorado River basin.
Woodhouse et al., 2006

45. Dave Meko University of Arizona

46. Source: Woodhouse et al., 2006

47. Relic tree, circa 323 BC Harmon Canyon, Utah

48. 1,200 years of Colorado River discharge Meko et al., GRL, 2007

49. “ The tree-ring record shows that droughts
lasting decades have routinely gripped
”
western North America.
Jonathan Overpeck and Bradley Udall

50. “ As western North America currently endures its
worst drought since 1900, it is important to realize
that this drought might be nothing compared to
what is possible in the future if megadrought and
”
even ho er temperatures coincide.
Jonathan Overpeck and Bradley Udall

52. Tree rings provided the central evidence that caused municipal water agencies to
“RETHINK OLD
ASSUMPTIONS”
about worst-case scenarios for reservoir operations and re-evaluate the
potential duration and geographic scope of severe drought.

53. READING FOR THURSDAY
David Meko and Connie Woodhouse (2010), Application of
streamflow reconstruction to water resources management.
M.K. Hughes et al. (eds.), Dendroclimatology, Developments in
Paleoenvironmental Research.

54. Please read the complete paper (eventually).

55. FOR NEXT CLASS
Read sections 8.3.3 and 8.3.4

56. MID-TERM
EXAM

58. “ They all laughed at me...
but I'LL SHOW THEM!
I'LL SHOW THEM ALL!!
”
BWAHAHAHAAA!

59. PLEASE WAIT
at least one day before asking
questions about your exam.

60. QUESTION 4
A common misconception is that dendrochronology
involves just counting tree rings. Describe three situations
that would lead simple ring counting to provide an
inaccurate estimate of tree age.

62. LAB
UPDATE

63. Photograph: Calvin Farris

64. Photograph: Lane Johnston