1. November 13
Dendroclimatology

2. Dr. Brian Luckman University of Western Ontario

3. “ Tree-ring-derived records have played a
prominent role in a empts to establish how
climate has varied in the recent past.
”
Jones et al.
The Holocene, 2009

4. What characteristics of tree-ring records
make them useful tools
to understand ancient climates?

5. CLIMATE FROM TREES
TAKING THE PLANET’S TEMPERATURE
COMPLICATIONS AND CHALLENGES

6. CLIMATE FROM TREES

7. 2010 Jan-Aug temperature anomaly h p://www.giss.nasa.gov/

9. Source: St. George and Luckman, 2001

10. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Ct = Rt - At - δD1t - δD2t - Et

11. THE PRINCIPLE OF
CROSS-DATING
THE PRINCIPLE OF
AGGREGATE TREE GROWTH
THE PRINCIPLE OF
REPLICATION
STANDARDIZATION
THE PRINCIPLE OF
ECOLOGICAL AMPLITUDE
THE PRINCIPLE OF
SITE SELECTION

12. How do we KNOW that tree rings are
tracking a SPECIFIC climate?

14. Source: Minyoung Choi

15. Single-site reconstruction

16. rain gauges
tree rings
Source: Hughes and Funkhouser, 1998

17. correlation The Pearson product-moment
correlation coefficient is probably the single
most widely used statistic for summarizing
the relationship between two variables.

18. variable ‘Y’
r = +1.0
variable ‘X’

19. variable ‘Y’
r = -1.0
variable ‘X’

20. variable ‘Y’
r = +0.85
variable ‘X’

21. Ring-width
index

22. CORRELATION
FUNCTION

25. Source: St. George and Luckman, 2001

26. Ring-width
index

27. Ring-width
index

28. yt = axt + b + ε

29. the climate variable
of interest (at year t)
yt = axt + b + ε
the tree-ring
variable (at year t)

31. Tree rings can provide extra-ordinarily good estimates (sometimes)
Source: Woodhouse et al., 2006

32. TAKING THE PLANET’S TEMPERATURE

34. Temperature-sensitive trees Northeastern Alaska

35. Long, temperature-sensitive tree-ring records have been used to estimate
average temperatures across the entire hemisphere or globe.
Source: Esper et al., Science, 2002

36. Source: Esper et al., Science, 2002

37. Source: D’Arrigo et al., 2006

38. Source: D’Arrigo et al., 2006

40. Source: Osborne and Briffa, 2006

42. “ Tree-rings also allow the reconstruction of
large-scale regional or global temperature pa erns
defined by large networks of chronologies.
”
Brian Luckman
Geoscience Canada, 2010

43. Source: Briffa et al., Global and Planetary Change, 2004

44. How do we KNOW that tree rings are
any GOOD at “reverse predicting”
past climate?

46. 1883
“THE LOUDEST SOUND IN MODERN HISTORY”

47. Krakatau, Indonesia 1883

48. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/

49. Mount Tambora, Indonesia Its eruption in 1815 was the most explosive since AD 180

50. 1816
THE “YEAR WITHOUT A SUMMER”

51. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/

52. Huaynaputina Peru

53. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/

54. Source: Briffa et al., Global and Biological Change, 2004

55. Photograph: Mark Anbinder

56. Source: Intergovernmental Panel on Climate Change, 2007

57. COMPLICATIONS AND CHALLENGES

58. “ Tree rings are not thermometers or rain gages.
Keith Briffa and colleagues
Climate Variations and Forcing Mechanisms of the Last 2000 Years, 1996
”

59. THE
DIVERGENCE
PROBLEM

60. Source: D’Arrigo et al., 2008

61. the ‘divergence problem’ is defined as the tendency
for tree growth at some previously temperature-
limited northern sites to demonstrate a weakening in
mean temperature response in recent decades.
Source: D’Arrigo et al., 2008

62. Source: D’Arrigo et al., 2008

63. “ It is important to stress that not all high-latitude
regions display this apparent decoupling
between observed and dendroclimatically
”
estimated temperatures.
Phil Jones and colleagues
The Holocene, 2009

64. Source: Briffa et al., Global and Biological Change, 2004

65. November 13
Dendroclimatology

66. Source: Intergovernmental Panel on Climate Change, 2007

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

68. “ Tree-ring-derived records have played a
prominent role in a empts to establish how
climate has varied in the recent past.
”
Jones et al.
The Holocene, 2009

69. GEOG5839
XT C L AS S
NE