Using modern weather data and ancient records of grape harvests, researchers have divined summer climate patterns in parts of Switzerland as far back as the late 1400s.
Temperature strongly influences the growth of grapevines and the ripening of their fruit, which makes the plants excellent climate sensors, says This Rutishauser, a climatologist at the University of Bern. He and his colleagues looked for climate clues in grape-harvest data for 15 locations in northern and western Switzerland.
Rutishauser says that grape-harvest data are available back to 1600 for all but a few years, such as 1879 to 1884, when various pests and diseases devastated Swiss vineyards. Gaps in harvest data are more frequent between 1480 and 1600, he notes.