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Large-scale dendrochronology and low-frequency climate variability

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Large-scale low-frequency variability has emerged as a priority for climate research, but instrumental observations are not long enough to characterize this behavior or gage its impacts on dependent geophysical or ecological systems. As the leading source of high-resolution paleoclimate information in the middle- and high-latitudes, tree rings are essential to understand low-frequency variability prior to the instrumental period. But even though tree rings possess several advantages as climate proxies, like other natural archives they also have their own particular impediments. In this lecture, Dr. St. George will describe the structure and characteristics of the Northern Hemisphere tree-ring width network, and outline how the fingerprint of decadal and multidecadal climate variability encoded within ancient trees varies across the hemisphere.

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Large-scale dendrochronology and low-frequency climate variability

  1. 1. LARGE-SCALE DENDROCHRONOLOGY AND LOW-FREQUENCY CLIMATE VARIABILITY KlimaCampus Colloquium, University of Hamburg | July 9 2015 Sco St. George University of Minnesota
  2. 2. DECADAL VARIABILITY
  3. 3. Source: Mohino et al., Climate Dynamics, 2011 SAHEL PRECIPITATION ANOMALIES (FILTERED TO EMPHASIZE LOW-FREQUENCY VARIABILITY)
  4. 4. PACIFIC DECADAL OSCILLATION
  5. 5. 1900 1920 1940 1960 1980 2000 2020 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 discharge (cfs) at Grand Forks, North Dakota Source: United States Geological Survey THE RED RIVER OF THE NORTH, LEAST STATIONARY RIVER IN THE USA
  6. 6. DECADAL PREDICTION, A NEW FIELD OF STUDY, FOCUSES ON TIME-EVOLVING REGIONAL CLIMATE CONDITIONS OVER THE NEXT 10-30 YR, WHICH IS A TIME PERIOD OF INTEREST TO INFRASTRUCTURE PLANNERS, WATER RESOURCES MANAGERS, AND OTHERS. “ ” Meehl et al., 2009 Bulletin of the American Meteorological Society
  7. 7. INSTRUMENTAL CLIMATE OBSERVATIONS
  8. 8. -34°CFORT SNELLING, MINNESOTA 30.1.1820
  9. 9. 1900 1920 1940 1960 1980 2000 2020 -4 -3 -2 -1 0 1 2 3 4 Source: Dr. Nate Mantua, University of Washington LOW-FREQUENCY VARIABILITY IN THE NORTH PACIFIC AS REPRESENTED BY THE PACIFIC DECADAL OSCILLATION INDEX
  10. 10. A LIMITATION OF THE INSTRUMENTAL RECORD IS THAT IT SPANS AT MOST A FEW REALIZATIONS OF DECADAL VARIABILITY. “ ” Solomon et al., 2011 Bulletin of the American Meteorological Society
  11. 11. Source: Deser et al., Annual Review of Marine Science, 2010 DISTRIBUTION OF SEA-SURFACE TEMPERATURE OBSERVATIONS FROM THE INTERNATIONAL COMPREHENSIVE OCEAN ATMOSPHERE DATA SET Percentage of months with at least one measurement
  12. 12. MODEL SIMULATIONS
  13. 13. Source: Delworth and Zeng, Geophysical Research Le ers, 2012 INVESTIGATING DECADAL TO MULTICENTENNIAL VARIABILITY OF NORTHERN HEMISPHERE SURFACE AIR TEMPERATURES IN A 4000-YR CONTROL SIMULATION
  14. 14. IN CCSM4, CENTENNIAL VARIABILITY ARISES PRIMARILY AS A THERMODYNAMIC RESPONSE TO EXPLOSIVE VOLCANISM. Source: Ault et al., Geophysical Research Le ers, 2013
  15. 15. … THE USE OF HIGH-RESOLUTION 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
  16. 16. Because temperate and boreal forests are so extensive, trees that form annual rings are very common. Trees routinely a ain ages in excess of several hundred years. ADVANTAGES OF TREE-RING WIDTHS
 AS CLIMATE PROXIES Source: St. George, Quaternary Science Reviews, 2014 Tree-ring records have annual resolution and the accuracy of their dating is confirmed by a rigorous cross-comparison procedure.
  17. 17. Tree-ring display at elementary school Photograph:Tom Swetnam
  18. 18. Dr. David Meko University of Arizona
  19. 19. Source: Meko et al., Geophysical Research Le ers, 2007 MULTI-CENTURY RECONSTRUCTIONS OF COLORADO RIVER FLOW FROM TREE-RING WIDTHS
  20. 20. PROXY ARCHIVES
  21. 21. … PRECIPITATION RECONSTRUCTIONS THAT ARE ENTIRELY BASED ON TREE-RING WIDTH CHRONOLOGIES MAY CONSIDERABLY OVERESTIMATE THE TRUE PERSISTENCE OF REGIONAL RAINFALL REGIMES. “ ” Bunde et al., 2013 Nature Climate Change
  22. 22. THESE LARGE VALUES OF SERIAL CORRELATION SUGGEST THAT THE NON-RANDOMNESS OF TREE-RING SEQUENCES IS DUE TO THE STORAGE OF FOOD PRODUCTS IN THE TREE RATHER THAN THE YEAR TO YEAR VARIATIONS OF RAINFALL OR SOIL MOISTURE. “ ” Matalas, 1962 International Association of Scientific Hydrology. Bulletin
  23. 23. ADVANTAGE DISADVANTAGE Short relative to decadal timescales Firmly grounded in reality Too sensitive to volcanic forcing? Simulations are much longer than the timescale of interest Long records grounded in reality Proxy systems may distort or exaggerate decadal signals THE DECADAL CLIMATE “CONUNDRUM”
  24. 24. Dr. Toby Ault Cornell University
  25. 25. 1DECVAR ALONG THE CENTRAL PACIFIC COAST
  26. 26. 2THE FIDELITY OF PALEO-PDO ESTIMATES
  27. 27. 3STRATEGIES TO TRACK PALEO-DECVAR
  28. 28. 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
  29. 29. 36 EARLYWOOD LATEWOOD ONE GROWTH RING
  30. 30. HOW MANY (COMPLETE) TREE RINGS ARE VISIBLE IN THIS MICROPHOTOGRAPH?
  31. 31. HOW MANY (COMPLETE) TREE RINGS ARE VISIBLE IN THIS MICROPHOTOGRAPH?
  32. 32. 1871 1872 1873 1874 Source: Dr. Dan Griffin, University of Minnesota
  33. 33. Source: Dr. Dan Griffin, University of Minnesota NORTHWESTERN NEW MEXICO
  34. 34. CRATER LAKE NATIONAL PARK
  35. 35. 1809 1811 181218081807 Source: Sarah Appleton, University of Minnesota
  36. 36. 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
  37. 37. Source: Esper et al., Dendrochronologia, 2013 If tree-ring records from Europe are shi ed back one year, their strong correlation with long temperature records disappears.
  38. 38. 0% 2% 4% 6% 8% 20°N 40°N 60°N 80°N Latitude Percentage of locally-absent rings b Picea Quercus Pinus Pseudotsuga Larix Other genera Source: St. George et al., Geophysical Research Le ers, 2013
  39. 39. Source: Büntgen et al., Nature Climate Change, 2014 Radiocarbon measurements of a subfossil pine (Pinus cembra) show the same 1.2% increase in 14C from AD 774 to 775.
  40. 40. ±0
  41. 41. 1DECVAR ALONG THE CENTRAL PACIFIC COAST
  42. 42. Source: Dr. Greg Brooks, Geological Survey of Canada RED RIVER, CENTRAL CANADA
  43. 43. Source: Flickr user kc7cbf
  44. 44. ‘WHITE’ total annual precipitation (mm) ANNUAL PRECIPITATION IN DES MOINES, IOWA Source: Global Historical Climate Network
  45. 45. Central Pacific Coast
  46. 46. 1920 1960 2000 −400 0 400 Regional winter precipitation anomalies (mm) Ault and St. George, Journal of Climate, 2010 CENTRAL PACIFIC COAST
  47. 47. 1920 1960 2000 −400 0 400 Regional winter precipitation anomalies (mm) Ault and St. George, Journal of Climate, 2010 CENTRAL PACIFIC COAST
  48. 48. THE HISTORY OF METEOROLOGY IS LITTERED WITH THE WHITENED BONES OF CLAIMS TO HAVE DEMONSTRATED THE EXISTENCE OF RELIABLE CYCLES IN THE WEATHER. “ ” William James Burroughs Weather Cycles: Real or Imaginary?
  49. 49. Source: California Department of Water Resources Florsheim, JL, De inger, MD, 2007. Climate and floods still govern California levee breaks. Geophysical Research Le ers.
  50. 50. Source: Ault and St. George, Journal of Climate, 2010 STRONG DECADAL VARIABILITY SYNCHRONIZES RAINFALL, STREAMFLOW, AND HAZARDS IN NORTHERN CALIFORNIA.
  51. 51. A STRONG ATMOSPHERIC RIVER
 CAN TRANSPORT 7-15X THE WATER IN THE MISSISSIPPI RIVER
  52. 52. … IN TODAY’S EMBANKED SYSTEM, 81% OF LEVEE BREAKS ALONG CENTRAL VALLEY RIVERS OCCURRED FLOODS GENERATED BY WINTERTIME [ATMOSPHERIC RIVERS] WITH ONLY 15% OCCURRING DURING SNOWMELT FLOODS. “ ” Florsheim and De inger, 2015 Geomorphic Approaches to Integrated Floodplain Management of Lowland Fluvial Systems in North America and Europe,
  53. 53. UNDER THE ‘HASSELMANN’ PARADIGM, THE LOW-FREQUENCY COMPONENTS ARE DRIVEN BY THE STOCHASTIC HIGHER-FREQUENCY ONES AND ARE NOT PREDICTABLE. days TIMESCALE VARIANCE decades high low months
  54. 54. ARE TREE-RING WIDTH RECORDS ABLE TO TRACK THIS PARTICULAR NARROWBAND FEATURE?
  55. 55. CRATER LAKE NATIONAL PARK
  56. 56. ) Winter precipitation Source: St. George, Quaternary Science Reviews, 2014 WINTER PRECIPITATION
  57. 57. Source: Dr. Dan Griffin, University of Minnesota QUERCUS DOUGLASII
  58. 58. 1700 1750 1800 1850 1900 1950 2000 Tree growth (anomalies) −0.4 0.4 0 1650 ring-width records mean of set Source: St. George and Ault, Journal of Geophysical Research - Atmospheres, 2011 TREE-RING WIDTH RECORDS FROM BLUE OAKS INDICATE THE 20TH CENTURY WAS UNUSUALLY DECADAL.
  59. 59. Source: Dr. Kevin Anchukaitis, University of Arizona ✔
  60. 60. days decadesmonths UNDER THE ‘BJERKNES’ PARADIGM, THE LONGER TIMESCALES MODULATE THE SHORTER ONES THROUGH OCEAN PROCESSES AND THEREFORE MAY BE PREDICTABLE. TIMESCALE VARIANCE high low
  61. 61. Source: NASA
  62. 62. 2THE FIDELITY OF PALEO-PDO ESTIMATES
  63. 63. PEYTO LAKE, CANADA
  64. 64. (c) Summer temperat Source: St. George, Quaternary Science Reviews, 2014 SUMMER TEMPERATURE
  65. 65. Source: Fri s et al., Journal of Applied Meteorology, 1971 SEASONAL PRESSURE ANOMALIES OVER THE NORTH AMERICAN SECTOR RECONSTRUCTED FROM 49 RING-WIDTH RECORDS
  66. 66. A LONG CLIMATIC RECORD CAN SERVE TO IDENTIFY THE RANGE OF POSSIBLE CLIMATES
 AND THE CHARACTERISTICS OF POSSIBLE CLIMATE “MODES”. “ ” Fri s et al., 1971 Journal of Applied Meteorology
  67. 67. Source: St. George, Quaternary Science Reviews, 2014 ENSO
  68. 68. PACIFIC DECADAL OSCILLATION
  69. 69. PDO D’ARRIGO AND WILSON, 2006 “ON THE ASIAN EXPRESSION OF THE PDO” D’ARRIGO ET AL., 2001 “TREE-RING ESTIMATES OF PACIFIC DECADAL CLIMATE VARIABILITY” BIONDI ET AL., 2001 “NORTH PACIFIC DECADAL CLIMATE VARIABILITY SINCE 1661” GEDALOF AND SMITH, 2001 “INTERDECADAL CLIMATE VARIABILITY AND REGIME-SCALE SHIFTS IN PACIFIC NORTH AMERICA” MACDONALD AND CASE, 2005 “VARIATIONS IN THE PACIFIC DECADAL OSCILLATION OF THE PAST MILLENNIUM”
  70. 70. Source: Newman et al,, in revision
  71. 71. … DROUGHTS OCCURRED DURING PERIODS OF BOTH WARM AND COOL KUROSHIO EXTENSION SSTS AND PERHAPS DURING POSITIVE AND NEGATIVE PDO, ALTHOUGH THIS IS DEPENDENT ON WHICH PDO RECONSTRUCTION IS USED. “ ” McCabe-Glynn et al., 2013 Nature Geoscience
  72. 72. Source: Newman et al,, in revision POOR REPRODUCIBILITY BETWEEN VARIOUS PDO RECONSTRUCTIONS CALLS TO QUESTION THEIR COLLECTIVE FIDELITY.
  73. 73. Source: Michael Chow BOULDER, COLORADO
  74. 74. Source: Kipfmueller et al., Geophysical Research Le ers, 2012 BLACK : WARM PHASE WHITE: COLD PHASE GREY: NO DATA 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.
  75. 75. WHY HAS IT BEEN SUCH A CHALLENGE TO RECONSTRUCT THIS ASPECT OF DECADAL VARIABILITY IN THE NORTH PACIFIC?
  76. 76. OCEAN SURFACE HEAT FLUX (VIA THE ALEUTIAN LOW) OCEAN MEMORY THE KUROSHIO-OYASHIO CURRENT + + THE PDO = Source: Newman et al,, in revision
  77. 77. SMALL SETS OF TREE-RING WIDTH DATA LARGE-SCALE GEOPHYSICAL PHENOMENA
  78. 78. Source: St. George, Quaternary Science Reviews, 2014 PDO
  79. 79. Pinus Picea Quercus Pseudotsuga Larix Nothofagus Austrocedris Phyllocladus Agathis Source: St. George, PAGES Magazine, 2014 There are more than 3,200 publicly-available tree-ring records (and many more held by individual investigators).
  80. 80. 3STRATEGIES TO TRACK PALEO-DECVAR
  81. 81. Source: Gray et al., Geophysical Research Le ers, 2003 Most dendroclimatic studies first reconstruct an annually-resolved target variable, and then apply some form of filter to emphasize decadal behavior.
  82. 82. IMPROVING ESTIMATES OF INTERMEDIATE-SCALE VARIABILITY
  83. 83. TREE-RING WIDTHS BECOME SMALLER 
 AS THE TREE GETS OLDER BECAUSE OF THE GEOMETRICAL CONSTRAINT CREATED
 BY ADDING A VOLUME OF WOOD TO A STEM OF INCREASING RADIUS.
  84. 84. [AGE-SIZE TRENDS IN TREE-RING WIDTH] SHOULD BE THOUGHT OF AS A NONSTATIONARY, STOCHASTIC PROCESS THAT MAY, AS A SPECIAL CASE, BE MODELED AS A DETERMINISTIC PROCESS. “ ” Cook and Briffa, 1990 Methods of Dendrochronology
  85. 85. (A) the ‘raw’ ring-width data
  86. 86. (B) the ‘detrended’ ring-width index
  87. 87. THE MOST OBVIOUS SOURCE OF NONCLIMATIC PERSISTENCE IN TREE-RING DATA
 IS ERROR IN REMOVAL OF THE GROWTH TREND WHEN CONVERTING ANNUAL RING WIDTHS TO TREE-RING INDICES. “ ” Meko, 1981 Doctoral dissertation, University of Arizona
  88. 88. PRESERVING DECADAL VARIANCE IN DENDROCLIMATIC RECONSTRUCTIONS
  89. 89. Dr. Toby Ault Cornell University
  90. 90. CHRONOLOGY RECONSTRUCTION mean-value function representing annual tree growth across many dozens or hundreds of trees quantitative estimate of a climate variable derived from one or several tree-ring chronologies
  91. 91. Source: Adapted from Ault et al., Journal of Climate, 2013 PALEO-PRECIPITATION RECONSTRUCTIONS FROM TREE RINGS HAVE LESS VARIANCE AT LOW FREQUENCIES
 THAN THE ORIGINAL TREE-RING CHRONOLOGIES.
  92. 92. Chronology ‘A’ Chronology ‘B’ Chronology ‘C’ Chronology ‘D’ Chronology ‘E’ Chronology ‘F’ Chronology ‘G’ Chronology ‘H’ Chronology ‘I’ Chronology ‘J’ Reconstruction 10 predictors76421 THE NESTED RECONSTRUCTION APPROACH GENERATES A NEW MODEL FOR EACH SUBSET OF PREDICTORS.
  93. 93. Source: Cook et al., Journal of Quaternary Sciences, 2010 THE NORTH AMERICAN DROUGHT ATLAS USES A NETWORK OF MOISTURE- SENSITIVE TREE-RING RECORDS TO ESTIMATE CHANGES IN DROUGHT CONDITIONS ACROSS THE CONTINENT.
  94. 94. 450 km A FIXED SEARCH RADIUS AROUND EACH GRID POINT DEFINES THE ZONE OF LOCAL CONTROL EXERCISED BY THE METHOD IN SELECTING CANDIDATE TREE-RING PREDICTORS OF PDSI. Source: Cook et al., Journal of Climate, 1999
  95. 95. CHOOSING ALTERNATIVE DECADAL TARGETS FOR RECONSTRUCTION
  96. 96. OCEAN SURFACE HEAT FLUX (VIA THE ALEUTIAN LOW) OCEAN MEMORY THE KUROSHIO-OYASHIO CURRENT + + THE PDO = Source: Newman et al,, in revision
  97. 97. IF THE RELATIVE IMPORTANCE OF THESE CONTRIBUTIONS VARIES, THEN THE APPARENT TELECONNECTION FROM THEIR SUM (THE PDO) COULD BE NONSTATIONARY EVEN IF TELECONNECTIONS TO THE INDIVIDUAL PDO PROCESSES WERE FIXED. “ ” Newman et al., in revision Bulletin of the American Meteorological Society
  98. 98. Source: Zanche in et al., Climate of the Past, 2015 PACIFIC/ NORTH AMERICAN PATTERN
  99. 99. THESE RESULTS CALL FOR STRENGTHENED COOPERATION BETWEEN THE CLIMATE PROXY AND CLIMATE MODELING COMMUNITIES IN ORDER TO IMPROVE OUR KNOWLEDGE ABOUT THE EARLY 19TH-CENTURY PNA AND TO SOLVE THE RELATED RECONSTRUCTION-SIMULATED DISCREPANCY. “ ” Zanche in et al., 2015 Climate of the Past
  100. 100. Dr. David Meko University of Arizona
  101. 101. Source: Meko, Ph.D. dissertation, 1981
  102. 102. TREE-RING RECORDS ARE ABLE TO TRACK DECADAL CLIMATE VARIABILITY, AT LEAST IN SOME CASES. BUT WE NEED TO SPECIFICALLY TEST THEIR FIDELITY AT THOSE TIMESCALES.
  103. 103. TREE-RING ESTIMATES OF DECADAL CLIMATE MODES ARE NOT CONSISTENT PRIOR TO THE 20TH CENTURY. THAT LACK OF AGREEMENT COULD TELL US SOMETHING ABOUT THE STABILITY OF TELECONNECTIONS ASSOCIATED WITH DECADAL MODES.
  104. 104. ACCURATELY EXTRACTING DECADAL SIGNALS FROM TREE-RING PROXIES IS A LONGSTANDING PROBLEM. THE PALEO-COMMUNITY MIGHT NEED TO ADOPT (AND TEST) NEW STRATEGIES TO DEAL WITH OUR PARTICULAR DECADAL ‘CONUNDRUM’.
  105. 105. SCOTT ST. GEORGE DEPARTMENT OF GEOGRAPHY, ENVIRONMENT AND SOCIETY UNIVERSITY OF MINNESOTA @SCOTTSTGEORGE

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