Information on Weather and Climate History in Historical Documents

Researchers use two different archives to reconstruct the weather and climate of the past:

Nature's archives store data created by natural processes. These include, for example, tree rings and ice cores. Such data is analysed using scientific methods.

Society's archives store information that has been created by humans. They are analysed using historical, artistic and literary methods. A distinction must be made between sources and data. A climate-historical source is a man-made unit of information that contains data on weather and climate.

They can be found in historical written and pictorial documents:

• Daily observations of the weather (temperature, cloud cover, wind, rain, snowfall, thunderstorms, hail, sleet) in weather diaries
• Descriptions of (unusual) weather events
• Descriptions of the causes and consequences of nature-induced disasters
• Early instrument measurements of temperature, air pressure, precipitation and runoff
• Water marks (high water marks, low water marks)
• References to bio-physical temperature indicators in the near-natural environment (proxy data):
  • vegetation development in the summer months (April to September)
  • snow cover, icing of lakes and rivers and extraordinary vegetation activity in the winter months (October to March)
• Image data (historical drawings, paintings and early photographs) for the reconstruction of former glacier levels and natural disasters