1. Tree ring records from across the Northern Hemisphere provide a powerful tool to study past climate, though the information that can be recovered varies regionally depending on climate influences on individual tree species. 2. The large global tree ring network allows understanding of tree-climate relationships without being influenced by decisions to include or exclude certain records, improving the accuracy of paleoclimate reconstructions. 3. Tree ring records have been used to generate reconstructions of large-scale climate drivers like the El Nino-Southern Oscillation and Pacific Decadal Oscillation, though conclusions depend on the choice of reconstruction method and data.

1. SEEINGTHEFORESTFOR
THETREE(RING)S
An overview of tree-ring width records
across the Northern Hemisphere
University of North Carolina | Department of Geography | October 24, 2014

4. Andrew Douglass Flagstaff 1898

6. Hal Fri"s 1964

7. Large sets of ring-width data have provided the foundation
for many proxy estimates of regional or global surface temperature.
Source: Intergovernmental Panel on Climate Change, AR5, Working Group 1

8. The Monsoon Asia Drought Atlas generated yearly maps of drought severity
Source: Cook et al., Science, 2010
based on ring-width and other tree-ring measurements.

9. Surrogate estimates of discharge have been used to produce ‘worst-case’
scenarios for water supplies in major western rivers, including the Colorado.
Source: Meko et al., Geophysical Research Le!ers, 2007

11. TREE-RING MYTHS

12. “IF NO RING WAS FORMED IN A GIVEN YEAR, ”
THAT CREATES A FURTHER COMPLICATION,
INTRODUCING AN ERROR
IN THE CHRONOLOGY ESTABLISHED BY
COUNTING RINGS
BACK IN TIME.
Dr. Michael Mann
Penn State News, February 6, 2012

13. “ MANY HIGH-RESOLUTION PALEOCLIMATE RECORDS,
SUCH AS THOSE BASED ON TREE RINGS,
”
ARE BIASED
TOWARDS RECORDING CLIMATE CONDITIONS
DURING THE SUMMER SEASON,
THE CRITICAL PERIOD FOR PLANT GROWTH.
Ersek et al., Nature Communications, 2012

14. “ CONVERSELY, GROWTH RATES IN
”
DROUGHT SENSITIVE TREES
ARE PRIMARILY CONTROLLED BY
SOIL MOISTURE CONTENT
DURING THE GROWING SEASON
(I.E., SPRING AND SUMMER)…
Steinman et al., Proceedings of the National Academy of Sciences, 2012

15. Source: Erika Wise

17. 1Despite their simplicity, the millions of observations that make up the
global tree-ring network provide us with a powerful and flexible tool
to study forest vigor and climate.

18. 2The climate ‘filtering’ conducted by individual trees creates major
regional differences in information that may be recovered from the
hemispheric network.

19. 3Because the Northern Hemisphere ring-width network is now so
large, our understanding of tree-environment relations must not be
influenced by decisions to include or exclude certain records.

22. Dr. Toby Ault Cornell University

23. MILLIONSOFRINGS

30. SIMPLE NOT ‘EASY’

31. How many tree rings
can you count?

32. Source: Peter Brown

33. Sarah Appleton Crater Lake, Oregon

35. Source: Sarah Appleton

36. 1807 1808 1809 1811 1812 1813
Source: Sarah Appleton

39. Source: Sarah Appleton

40. The trees composing the forest rejoice and
lament with its successes and failures and
carry year by year something of its story in
their annual rings.” “
A. E. Douglass
University of Arizona

41. Source: Baillie (1982)

44. Source: Phil Camill

45. Source: Uday Kunwar Thapa

46. The International Tree-Ring Database holds more than 3,200 records
Pinus
Picea
Quercus
Pseudotsuga
Larix
Nothofagus
Austrocedris
Phyllocladus
Agathis
Source: St. George, PAGES News, 2014
from every continent except Antarctica.

48. 1Despite their simplicity, the millions of observations that make up the
global tree-ring network provide us with a powerful and flexible tool
to study forest vigor and climate.

49. THEIMPRINTOFCLIMATE

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

51. Dr. Hal Fri"s University of Arizona

52. Fri"s, H.C. Growth-rings of trees: their correlation with climate. Science 154, 973-975 (1966).

53. “THROUGH SEVERAL DIFFERENT STUDIES ”
MY ASSOCIATES AND I HAVE ACCUMULATED
MORE THAN 40 REPLICATED SAMPLES
OF TREE RINGS FROM A VARIETY OF SPECIES AND SITES
NEAR WEATHER STATIONS HAVING
RELATIVELY LONG AND CONTINUOUS RECORDS,
IN ARIZONA, COLORADO, CALIFORNIA,
AND ILLINOIS.
Dr. Hal Fri"s
Science, 1966

54. LOW-ELEVATION FORESTS
IN SEMI-ARID REGIONS
carry-over effects
from wintertime climate
HIGH-ELEVATION OR
HIGH-LATITUDE FORESTS
climate during the growing season

55. The principles outlined by Fri"s have guided the collection of tree-ring
records at thousands of locations around the planet since the 1970s.
Pinus
Picea
Pseudotsuga
Quercus
Larix
A
C
36ºN
18ºN
records
records
B
54ºN
72ºN
90ºN
180ºW 120ºW 60ºW 0º 60ºE 120ºE 180ºW
2000
1000
12%
6%
0º
Source: St. George et al., Geophysical Research Le!ers, 2013

56. -0.8 -0.6 -0.4 -0.2 +0.2 +0.4 +0.6 +0.8
correlation coefficient
(ring-width vs. local climate)

57. (a) Winter precipitation
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014

58. Winter precipitation
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014

59. WINTER PRECIPITATION
(a) Winter precipitation
(b) Summer precipitation
Source: St. George, Quaternary Science Reviews, 2014

63. (b) Summer precipitation
SUMMER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014

64. (b) Summer precipitation
SUMMER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014

65. SUMMER PRECIPITATION
(b) Summer precipitation
(c) Summer temperature
Source: St. George, Quaternary Science Reviews, 2014

67. (c) Summer temperature
SUMMER TEMPERATURE
-0.8 -0.6 -0.4 -0.2 +0.2 +0.4 +Source: St. George, Quaternary Science Reviews, 2014

68. (c) Summer temperature
SUMMER TEMPERATURE
Source: St. George, Quaternary Science Reviews, 2014
-0.6 -0.4 -0.2 +0.2 +0.4 +0.6 +0.8

69. SUMMER TEMPERATURE
(c) Summer temperature
-0.8 -0.6 -0.4 -0.2 +0.2 +0.4 +0.6 +0.8
Source: St. George, Quaternary Science Reviews, 2014

71. Fri"s, H.C. Growth-rings of trees: their correlation with climate. Science 154, 973-975 (1966).

72. summer
temperature
winter
precipitation
summer
precipitation

73. summer
temperature
winter
precipitation
summer
temperature
summer
precipitation
winter
precipitation
summer

74. summer
temperature
winter
precipitation
summer
precipitation

75. GEOGRAPHICBIASES

76. Angiosperms (including Quercus) diverged from the gymnosperms at least 140 mya.

77. Xiaolu (Grace) Li Cornell University

78. Vaganov et al., In Dendroclimatology, 2010

79. Synthetic tree-ring records generated by a forward model (and modern climate data)
oW
120exhibit the same spatial pa"erns in climate response as do real trees.
60oW
0o 60oE
120oE
75oN
90oN
SOIL MOISTURE : TEMPERATURE
Source: LI et al., in preparation

80. 2The climate ‘filtering’ conducted by individual trees creates major
regional differences in information that may be recovered from the
hemispheric network.

82. Cook et al., Earth Science Reviews, 2007

83. PLANETARYDENDROCLIMATOLOGY

84. The International Tree-Ring Database holds more than 3,200 records
Pinus
Picea
Quercus
Pseudotsuga
Larix
Nothofagus
Austrocedris
Phyllocladus
Agathis
Source: St. George, PAGES News, 2014
from every continent except Antarctica.

85. BENEFITS OF LARGE NETWORKS
assign more weight to behavior exhibited by
many records and tree species
reduce emphasis given to unusual records
that may be dominated by non-climatic noise
improve the accuracy of paleoclimate reconstructions
Source: Meko et al., Journal of Climate, 1993

86. Climate field reconstructions can only be produced
through analysis of large arrays of proxy data.
Source: Wise and Dannenberg, Nature Communication, 2014

87. ENSO
El Niño-Southern Oscillation
PDO
Pacific Decadal Oscillation

88. H H
PACIFIC
WARM POOL

89. “El Niño-Southern Oscillation-related
hydroclimatic variability in the western
United States is characterized by a north–
south dipole pa"ern of precipitation
anomalies with opposing signs.”
Source: Wise, Geophysical Research Le!ers, 2010

90. EL NIÑO enhances tree growth
LA NIÑA suppresses tree growth

91. ENSO
Source: St. George, Quaternary Science Reviews, 2014

94. PACIFIC
DECADAL
OSCILLATION

95. ... the use of high-resolution paleoclimate proxy data should be
expanded because the short observational record and model
uncertainty are unable to simulate [Decadal Climate Variability]... “ ”
Mehta et al., 2011
Bulletin of the American Meteorological Society

96. PDO
Source: St. George, Quaternary Science Reviews, 2014

97. There are several proxy estimates of the PDO index during the past
several centuries, each developed from different sets of tree-ring data
Source: Kipfmeuller et al, Geophysical Research Le!ers, 2012
and a variety of reconstruction approaches.

98. Dr. Kurt Kipfmueller University of Minnesota

99. “ ANY CONCLUSION
”
THAT EXTENSIVE WILDFIRES ARE
MORE OR LESS COMMON
WHEN THE PDO IS IN ONE PHASE OR THE OTHER
DEPENDS ENTIRELY
ON THE CHOICE OF PDO RECONSTRUCTION.
Kipfmueller et al., Geophysical Research Le!ers, 2012

100. The International Tree-Ring Database holds more than 3,200 records
Pinus
Picea
Quercus
Pseudotsuga
Larix
Nothofagus
Austrocedris
Phyllocladus
Agathis
Source: St. George, PAGES News, 2014
from every continent except Antarctica.

101. TYPE 1
ERROR

102. LARGE POOL
OF POTENTIAL CANDIDATES
SMALL NUMBER
OF PREDICTORS

103. 3Because the Northern Hemisphere ring-width network is now so
large, our understanding of tree-environment relations must not be
influenced by decisions to include or exclude certain records.

108. The International Tree-Ring Database holds more than 3,200 records
Pinus
Picea
Quercus
Pseudotsuga
Larix
Nothofagus
Austrocedris
Phyllocladus
Agathis
Source: St. George, PAGES News, 2014
from every continent except Antarctica.