1. CONTEMPORARY ISSUES
IN THE STUDY OF
ANCIENT CLIMATES
CLIMATE SCIENCE, STATISTICS AND THE COMPUTATIONAL SCIENCES READING GROUP
APRIL 2012

3. anecdote

4. “ It doesn't really seem like winter. It seems
more like an unusual fall that kind of lingers
on and doesn't go anywhere.
”
Jessica Forster
Commenting on the mild 2012 winter in Minnesota

5. observation

6. Weather data recorded by the Department of Earth Sciences h p://sokar.geo.umn.edu/weather/

8. The Central England Temperature record is
the longest instrumental record of temperature in the world.
Degrees celsius relative to the long-term mean
Source: Parker et al., Journal of Climate, 1992

9. Source: Goddard Institute for Space Studies, NASA

10. The number of climate stations recording air temperature
falls off rapidly prior to AD 1900.
Number of stations in the Northern Hemisphere
Source: Jones et al., Journal of Geophysical Research, 2012

11. anecdote < observations <<

12. ‘Striations’ (scratches) on bedrock
near Knife Lake, BWCAW
Source: Blue~Canoe

13. Thickness of glacial ice
3000 m
IDS Tower
241 m

14. CLIMATE HISTORY OF NORTH AMERICA
Younger Demise of Laurentide
Dryas Ice Sheet
20 16 12 8 4 0
THOUSANDS OF
YEARS AGO
Final Drainage
of Lake Agassiz
LAST GLACIAL MODERN
MAXIMUM OBSERVATIONS

15. CLIMATE PROXIES
ice cores
tree rings
lake sediments
speleothems
corals

16. CLIMATE
“PROXIES”
natural phenomena which are climate-dependent,
and which incorporate into their structure a measure of this dependency.
Source: Bradley, Paleoclimatology: Reconstructing climates of the Quaternary, 1995

17. Source: Tim Shanahan, University of Texas at Austin

19. Source: Geological Survey of Canada

20. Source: LACCORE, University of Minnesota

21. Source: Stella Cousins

22. “ To anticipate future changes, we must understand
how and why climates varied in the past.
Dr. Ray Bradley
University of Massachuse s
”

23. PALEOCLIMATOLOGY
the study of climate prior to the period of instrumental measurement

24. Global networks of climate proxies have been used
to estimate past changes in hemispheric temperature.
Source: Commi ee on Surface Temperature Reconstructions for the Last 2,000 Years, National Research Council, 2006

25. How did the ENSO system behave prior to the 20th century?

26. Tree-ring estimates of 1,200 years of Colorado River discharge Meko et al., GRL, 2007

27. OBSERVATIONS PROXIES MODELS

29. “ Each individual proxy provides a record of environmental change,
but the process of combining these signals into a spatially averaged
temperature signal requires careful statistical evaluation.
Commi ee on Surface Temperature Reconstructions for the Last 2,000 Years
”
National Research Council

30. ?
How can we extract climatic signals from
a large, diverse network of noisy proxies that
are distributed irregularly around the planet?

33. Tree-ring display at elementary school
Source: Tom Swetnam

34. Intermountain bristlecone pine 4,844 years
Source: Tom Harlan

35. Giant sequoia 3,266 years
Source: Julie Jordan Sco

36. Eastern white cedar (in Minnesota) 560 years
Source: Danny Margoles

38. Pinus spp.
Source: Paul Schulte

39. Source: Baillie (1982)

42. 755 m3/s
847 m 3/s
809 m 3/s
770 m 3/s
823 m 3/s
787 m 3/s
901 m3/s
3

43. TEMPERATURE
high growth
frozen water
low photosynthetic rate
low photosynthetic rate
higher evaporation
shorter growing season
low growth
cold hot

44. WATER
high growth
reduced cell division
flooding
reduced cell expansion
anoxic conditions
C02 starvation
low growth
dry wet

45. Single-site reconstruction

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

48. “ THERMOMETERS ”
TREES ARE NOT
OR RAIN GAUGES.
Keith Briffa and colleagues

49. 3
CHALLENGES
IN DENDROCLIMATOLOGY

50. 3 Do climate-sensitive trees (and other proxies)
transform climate signals in predictable ways?

51. 2 Is there an optimal approach for recovering
low-frequency variability from climate-sensitive tree rings?

52. 1
Should paleoclimatic estimates from trees be derived
from (a) common pa erns or (b) optimal predictors?

53. Source: Baillie (1982)

54. Network reconstruction

55. “ Continental- and hemispheric-scale networks contain
robust synoptic-scale pa erns, which may o en be
interpreted in terms of climatic conditions.
Dr. Malcolm Hughes
”
University of Arizona
Source: Hughes, Dendroclimatology, 2010

56. Tree-ring records in North America circa 1990
Source: Meko et al., Journal of Climate, 1991

57. Major regional pa erns recovered from North American tree rings
Source: Meko et al., Journal of Climate, 1991

58. Tree-ring data used to estimate past drought in North America Cook et al., Journal of Quaternary Sciences, 2010

59. One thousand years of drought in western North America Cook et al., Science, 2004

60. alternative

61. ‘Optimal’ reconstruction

62. PACIFIC
DECADAL
OSCILLATION

64. Pacific Decadal Oscillation index
3
2
1
0
-1
-2
-3
1900 1920 1940 1960 1980 2000

65. Are these two records more closely tuned to the North Pacific Ocean
than other tree-ring data from North America?
Source: MacDonald and Case, Geophysical Research Le ers, 2005

67. “ This method of selecting proxies by screening a potentially
large number of candidates for positive correlations
runs the danger of choosing a proxy by chance.
Gerg Bürger
Freie Universität-Berlin
”
Source: Bürger, Science, 2007

69. Carlo Emilio Bonferroni
1892 - 1960

71. 2 Is there an optimal approach for recovering
low-frequency variability from climate-sensitive tree rings?

72. 20-day weather simulation from NASA’s GEOS-5 model

74. DECADAL
CLIMATE VARIABILITY

76. Benoit Mandelbrot March 2007

77. “ We shall speak of “Joseph-wild” behavior when the we est decade
within a century includes an extraordinary “term” of wet years.
”

78. Central Pacific Coast

79. Ault and St. George, Journal of Climate, 2010

80. Ault and St. George, Journal of Climate, 2010

81. “ The decadal time scale offers
a critical bridge for informing
adaptation strategies as
”
climate varies and changes.
Meehl et al., BAMS, 2009

82. ~10 yr
~100 yr
=
variability
low ‘n’
observations

83. “ ... 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.
Bulletin of the American Meteorological Society
2011

84. Source: Dan Griffin

85. DIFIED
M O
SINGULAR
SPECTRUM
ANALYSIS

86. x(t)
y(t)
tEOFs
reconstructed sibling
components components

87. really
not that
decadal
decadal
Source: St. George and Ault, Journal of Geophysical Research - Atmospheres, 2011

88. How well does this approach characterize decadal variability?
Ault and St. George, Journal of Climate, 2010

89. 3 Do climate-sensitive trees (and other proxies)
transform climate signals in predictable ways?

90. WATER
high growth
reduced cell division
flooding
reduced cell expansion
anoxic conditions
C02 starvation
low growth
dry wet

91. ∆S

92. “ Discharge or lake records ‘‘have a tendency to
exhibit more pronounced and smoother cycles’’
than precipitation because of storage.
”
Vit Klemeš

93. Do proxies
PUMP UP
low-frequency signals?

94. Source: Jansen Cardy
Sarah Truebe University of Arizona

95. Truebe et al., IOP Conference Series : Earth and Environmental Science, 2010

96. WATER
high growth
reduced cell division
flooding
reduced cell expansion
anoxic conditions
C02 starvation
low growth
dry wet

97. “ [L]inear empirical–statistical analyses alone cannot be used
to prove a physical or biological mechanism for variability or
”
change in the climate-tree growth relationship.
Anchukaitis et al., Geophysical Research Le ers, 2007

98. Even a simple cambial model can reproduce the main features in real tree-ring data from Russia
Source: Evans et al., Journal of Geophysical Research, 2006

99. Pinus spp.
Source: Paul Schulte

100. CONTEMPORARY ISSUES
IN THE STUDY OF
ANCIENT CLIMATES
CLIMATE SCIENCE, STATISTICS AND THE COMPUTATIONAL SCIENCES READING GROUP
APRIL 2012

101. “ Tree-ring analysis is one of the most powerful tools
available for the study of environmental change
and the identification of fundamental relationships
”
between tree growth and climate.
Ed Cook and Neil Pederson
Lamont-Doherty Earth Observatory

103. Toby Ault National Corporation for Atmospheric Research