1. Source: St. George and Luckman, 2001

2. Source: St. George and Luckman, 2001

3. Source: St. George and Luckman, 2001

4. a.k.a. Empirical Orthogonal Function analysis
PRINCIPLE COMPONENTS
ANALYSIS

7. PC1 (group 1)
PC3 (group 3)
PC2 (group 2)

8. Source: St. George and Luckman, 2001

9. Source: St. George and Luckman, 2001

10. most sites
Source: St. George and Luckman, 2001

11. most sites
farthest
north
Source: St. George and Luckman, 2001

12. most sites
farthest
north
unusual
site
Source: St. George and Luckman, 2001

13. LINEAR
REGRESSION

14. yt = axt + b + ε

15. Tjj = 0.23PC1 + -0.23PC3t+1
+ 0.16PC2t+1 + -0.09PC1t+1
+ -0.46

16. Source: St. George and Luckman, 2001

17. “ 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

18. G L O B A L T E M P E R AT U R E R E C O N S T R U C T I O N S
Photograph: Marianna

19. 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

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

21. Source: D’Arrigo et al., 2006

22. Source: D’Arrigo et al., 2006

23. Source: Osborne and Briffa, 2006

24. “ ...this study provides evidence for intervals of
significant warmth in the [Northern Hemisphere]
within the so-called Medieval Warm Period and for
significantly colder intervals during the so-called
”
Li le Ice Age period.
— Osborne and Briffa, 2006

25. LINEAR
REGRESSION

26. Source: Intergovernmental Panel on Climate Change, 2007

27. Photograph: Mark Anbinder

28. “ Tree-rings also allow the reconstruction of large-scale
regional or global temperature pa erns defined by
large networks of chronologies.
”— Brian Luckman

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

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

31. 1883
“THE LOUDEST SOUND IN MODERN HISTORY”

32. Krakatau, Indonesia 1883

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

34. 1816
THE “YEAR WITHOUT A SUMMER”

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

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

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

38. Huaynaputina Peru

39. “Trees are not thermometers or rain gagues.” Keith Briffa and colleagues

40. THE
DIVERGENCE
PROBLEM

41. 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

42. Source: D’Arrigo et al., 2008

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

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

45. Source: D’Arrigo et al., 2008

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