3. White cedar 1452
Source: Danny Margoles

4. Bur oak >450 yr
Source: Joe Zeleznik NDSU

6. 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

7. DECADAL
CLIMATE VARIABILITY

8. “ ‘Drought’ people get. ‘Decadal-scale climate variability’
gets me that glazed eye look.
John Fleck
Albuquerque Journal
”

9. Behold, there comes seven years of great plenty throughout
all the land of Egypt: And there shall arise a er them seven
years of famine; and all the plenty shall be forgo en in the
land of Egypt; and the famine shall consume the land;
Genesis 41, 29-30

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

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

12. Atlantic Multidecadal Oscillation index

14. “ An improved understanding of [Decadal Climate Variability] is very important because
stakeholders and policymakers want to know the likely climate trajectory for the coming decades
for applications to water resources, agriculture, energy, and infrastructure development. ”

15. Observations Models
Proxies

16. THE DECADAL
BLIND SPOT

17. MINNESOTA
THE DECADAL BLIND SPOT
OBSERVATIONS

18. Source: Franklin Hunting

19. The Atlantic Multidecadal Oscillation and its relation
to rainfall and river flows in the continental U.S.
David B. Enfield, Alberto M. Mestas‐Nuñez and Paul J. Trimble
Geophysical Research Le ers, 2001

21. Does the state of the PDO and AMO influence the frequency of drought?
AMOnegative AMOpositive
PDOpositive
PDOnegative
McCabe et al, Proceedings of the National Academy of Sciences, 2004

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

23. OCEAN

24. LAND

25. Toby Ault National Corporation for Atmospheric Research

26. Is precipitation every red?

27. Using singular spectral analysis
to decompose precipitation records
Ault and St. George, Journal of Climate, 2010

28. GEOGRAPHY
MATTERS A LOT

29. Decadal ‘hotspots’ in winter precipitation
0% 10% 20% 30% variance
Ault and St. George, Journal of Climate, 2010

30. Central Pacific Coast

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

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

33. NOT
LOCALLY FIELD
SIGNIFICANT SIGNIFICANT

34. Carlo Emilio Bonferroni
1892 - 1960

35. Decadal ‘hotspots’ in winter precipitation
0% 10% 20% 30% variance
Ault and St. George, Journal of Climate, 2010

37. “ ... 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

39. MINNESOTA
THE DECADAL BLIND SPOT
PROXIES

41. “ RINGS
IN THE BRANCHES OF
SAWED TREES SHOW
THE NUMBER OF YEARS
AND, ACCORDING TO THEIR
THICKNESS,
THE YEARS WHICH WERE
MORE OR LESS
DRY.”
Leonardo da Vinci

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

43. water stress
narrow ring reduced photosynthesis
less cell expansion
reduced cell division

45. Central Pacific Coast

46. Source: Dan Griffin

47. St. George and Ault, Journal of Geophysical Research - Atmospheres, 2011

48. really
decadal
St. George and Ault, Journal of Geophysical Research - Atmospheres, 2011

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

50. 7 track this signal
23 don’t

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

52. White pine 1714
Source: Kurt Kipfmueller

53. ∆S

54. Vit Klemeš
1932 - 2010

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

56. Do proxies
PUMP UP
low-frequency signals?

57. Source: Stella Cousins

58. Source: Jansen Cardy
Sarah Truebe University of Arizona

59. Source: Sarah Truebe, University of Arizona

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

61. “ ...variability in this range [less than 100 years]
can represent a mixed signal of climate input
and subsurface storage.
”
Truebe et al.
IOP Conference Series : Earth and Environmental Science, 2010

62. Observations Models
Proxies

63. MINNESOTA
THE DECADAL BLIND SPOT
MODELS

65. “ Although global coupled models designed in the last 15 years
are able to generate DCV pa erns that resemble observed
DCV pa erns, the models tend to displace them spatially
”
and temporally with respect to observed pa erns.
Mehta et al.
Bulletin of the American Meteorological Society
2011

66. Toby Ault National Corporation for Atmospheric Research

67. The power-law scaling parameter
β
relates variance to timescale.

68. The spectrum of SST observations is either ‘red’ or ‘white’
Beta value of SST

69. The spectrum of simulated SST is too ‘white’ or too ‘blue’
Beta value of SST

70. Because the interannual components are too energetic,
is it possible they might be forcing decadal components in unrealistic ways?

71. THE DECADAL
BLIND SPOT

72. Observations Models
Proxies

73. 1
We need to test the ability of models to
simulate terrestrial climates at decadal timescales.

74. 2
We need to use (or develop) physically-based
forward models to test how proxies record
(and possibly distort) low-frequency climate signals.

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