GEOG5839.19, Dendroclimatology

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GEOG5839.19, Dendroclimatology

  1. 1. November 13Dendroclimatology
  2. 2. Dr. Brian Luckman University of Western Ontario
  3. 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. 4. What characteristics of tree-ring records make them useful tools to understand ancient climates?
  5. 5. CLIMATE FROM TREESTAKING THE PLANET’S TEMPERATURECOMPLICATIONS AND CHALLENGES
  6. 6. CLIMATE FROM TREES
  7. 7. 2010 Jan-Aug temperature anomaly h p://www.giss.nasa.gov/
  8. 8. Source: St. George and Luckman, 2001
  9. 9. THE PRINCIPLE OF AGGREGATE TREE GROWTH Ct = Rt - At - δD1t - δD2t - Et
  10. 10. THE PRINCIPLE OF CROSS-DATING THE PRINCIPLE OFAGGREGATE TREE GROWTH THE PRINCIPLE OF REPLICATION STANDARDIZATION THE PRINCIPLE OFECOLOGICAL AMPLITUDE THE PRINCIPLE OF SITE SELECTION
  11. 11. How do we KNOW that tree rings are tracking a SPECIFIC climate?
  12. 12. Source: Minyoung Choi
  13. 13. Single-site reconstruction
  14. 14. rain gauges tree ringsSource: Hughes and Funkhouser, 1998
  15. 15. correlation The Pearson product-momentcorrelation coefficient is probably the singlemost widely used statistic for summarizingthe relationship between two variables.
  16. 16. variable ‘Y’ r = +1.0 variable ‘X’
  17. 17. variable ‘Y’ r = -1.0 variable ‘X’
  18. 18. variable ‘Y’ r = +0.85 variable ‘X’
  19. 19. Ring-width index
  20. 20. CORRELATION FUNCTION
  21. 21. Source: St. George and Luckman, 2001
  22. 22. Ring-width index
  23. 23. Ring-width index
  24. 24. yt = axt + b + ε
  25. 25. the climate variableof interest (at year t) yt = axt + b + ε the tree-ring variable (at year t)
  26. 26. Tree rings can provide extra-ordinarily good estimates (sometimes)Source: Woodhouse et al., 2006
  27. 27. TAKING THE PLANET’S TEMPERATURE
  28. 28. Temperature-sensitive trees Northeastern Alaska
  29. 29. 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
  30. 30. Source: Esper et al., Science, 2002
  31. 31. Source: D’Arrigo et al., 2006
  32. 32. Source: D’Arrigo et al., 2006
  33. 33. Source: Osborne and Briffa, 2006
  34. 34. “ 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
  35. 35. Source: Briffa et al., Global and Planetary Change, 2004
  36. 36. How do we KNOW that tree rings are any GOOD at “reverse predicting” past climate?
  37. 37. 1883“THE LOUDEST SOUND IN MODERN HISTORY”
  38. 38. Krakatau, Indonesia 1883
  39. 39. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/
  40. 40. Mount Tambora, Indonesia Its eruption in 1815 was the most explosive since AD 180
  41. 41. 1816THE “YEAR WITHOUT A SUMMER”
  42. 42. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/
  43. 43. Huaynaputina Peru
  44. 44. h p://www.cru.uea.ac.uk/cru/people/briffa/temmaps/
  45. 45. Source: Briffa et al., Global and Biological Change, 2004
  46. 46. Photograph: Mark Anbinder
  47. 47. Source: Intergovernmental Panel on Climate Change, 2007
  48. 48. COMPLICATIONS AND CHALLENGES
  49. 49. “ Tree rings are not thermometers or rain gages. Keith Briffa and colleagues Climate Variations and Forcing Mechanisms of the Last 2000 Years, 1996 ”
  50. 50. THEDIVERGENCE PROBLEM
  51. 51. Source: D’Arrigo et al., 2008
  52. 52. 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
  53. 53. Source: D’Arrigo et al., 2008
  54. 54. “ 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
  55. 55. Source: Briffa et al., Global and Biological Change, 2004
  56. 56. November 13Dendroclimatology
  57. 57. Source: Intergovernmental Panel on Climate Change, 2007
  58. 58. SURFACE TEMPERATURERECONSTRUCTIONSFOR T HE LAS T 2, 0 00 Y E A R S NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES
  59. 59. “ 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
  60. 60. GEOG5839 XT C L AS SNE

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