HISTORICAL DATA:

• A unique human perspective: information in diaries and other documents given climatic interpretation
  
• Unique biases
  • Written record biased toward extreme events (e.g., droughts, floods) and can be used to reconstruct frequency of extreme events
    
  • Written records biased toward short-term (< 20 yr) climate change because people adjust to longer changes (longer than one generation)
    
  • EXAMPLE: "Tucson summers are hotter than they used to be"
    

• author's personal biases
  • Standardize each author's observations ("mild" to "severe")
    
• second-hand information sometimes quoted as personal observation
  • Data from another area or another time
• Non-climatic impact of human activities on environmental record
  • construction of dams (floods)
    
  • construction on floodplains (floods)
    
  • construction of irrigation canals (droughts)
    

1. Instrumental records
   • most reliable (but, changes in recording station, heat island)
   • short time scale: 100 yr in W US
   
   
2. Primary observations (result from specific meteorological condition)
   • timing of frosts (air temperatures < 0 ^oC)
   • snowfall depth (not same as precipitation)
3. Weather-dependent phenomena: (result from complex meteorological conditions)
   
   • freezing of lakes, rivers, canals
     
   • droughts, floods
     
   • time scale: up to 5000 years in China, < 100 yr Australia
     
4. Phenologies: seasonal biological phenomena
   • dates of flowering, fruiting, harvest
     
   • dates of migrations
   • NGDC
   • National Phenology Network
5. Economic Production:
   • harvest
     
   • catch
     
6. Historic Photographs (Matched Pairs)
   • spotty coverage
     
   • short time scale
     
   • 0.4-1.2°C LIA cooling Uintas (Munroe 2003)
   
   

   Matched Photograph Pairs

   • Earliest Photographs 150 yrs old
     
   • Provide visual documentation of environmental (vegetation, geomorphic) change
     
   • EXAMPLE: desert grassland and Sonoran upland invaded by mesquite, creosote bush, juniper
     (Turner et al., 2003; Davis Turner, 1986; Hastings & Turner, 1965)

     Tucson, Santa Cruz 1904	Tucson, Santa Cruz 1981
     Landscape Changes in the Southwestern United States: Allen, Betancourt, & Swetnam
     BLM NPS Pages

   
   EXAMPLES OF WRITTEN DOCUMENTS:
   • number of days with snow lying on ground in Zurich
     
   • number of frosts per decade
     
   • droughts/floods
     
   • freezing of rivers, lakes
     
   • average date of grape harvest
     
   
   Tax records:
   
   
   CALIBRATION OF HISTORIC DOCUMENTS: relating weather-dependent phenomena to written record
   • Example sea ice -- mean annual temperature
     • canal freezing -- mean winter temperature
       
       
       
       
     • spring temperature -- first flowering
   
   Example: EL NIÑO History from historic documents:
   Quinn and Neal (1992) El Niños 5-point scale strength
   • Moderate
   • Moderate+
   • Strong
   • Strong+
   • Very Strong
   El Niño Strength Scale was considered
   1. high sea & air temp.
   2. red tides
   3. rain & floods
   4. raises in sea level
   5. departure of guano birds
   6. drastic reduction in fisheries . . .
   
   based on historic data
   
   
   based on geochemical data
   
   

   EUROPEAN HISTORIC CLIMATIC EVENTS

   1. Medieval Warm Period = Medieval Optimum = Viking Period
      A.D. 1050 - 1350 Greenland's temp. 2-4^oC higher than today
      • Viking colonization of Greenland, North America
        
      • wheat, oats, barley grown in Iceland, Norway
        
      • English vineyards productive
        
      • Scottish farming in the highlands
        
      • Southwestern population maximum
      • Southwestern climate optimum
   2. Little Ice Age
      A.D. 1350 - 1910 1-3^oC colder than today (Campbell & McAndrews, 1993)
      • Viking colonies had already collapsed
        
      • Many tax assements reduced due to cold-related disasters
        
      • Dutch Canals Frozen
        
      • French Grape Harvest reduced
        
      • LIA events are associated with DROUGHTS in monsoonal Africa
        (Verschuren et al., 2000)
   
   

   SOUTHWESTERN PREHISTORIC CLIMATIC EVENTS

   1. Greater Summer Precipiation AD 1000 - 1400
      600 - 1000 years ago
      
      • population maxima for 19 of 27 Puebloan Sites on Colorado Plateau
      • population maximum in Tucson
        
        
   2. Arroyo Cutting
      • before 1890s Santa Cruz River meandering stream, grist mill near A-Mountain
        
      • example of complex interaction of cattle, climate, land use
        
   3. 1910 coldest, wettest in meteorological record
      • but used in calculating water volume for dams, irrigation
        
   
   
   Historical Readings
   
   HOMEWORK