Researchers have reconstructed the climate of 17th-century Transylvania by examining hundreds of historical documents, including town records, church logs, travel accounts, and administrative and monastic diaries. The region, located in present-day Romania, experienced the effects of the Little Ice age, a period of unusually cold and unstable conditions that affected Europe for centuries.
The study, published in PLOS Climate, was led by Ovidiu Răzvan Gaceu of the University of Oradea. The research team collected 937 written accounts from 68 Transylvanian localities. The documents contained direct descriptions of weather, indirect signs such as delayed crop ripening and frozen rivers, and reports of consequences including destroyed harvests and rising food prices.
To assess the reliability of the evidence, two researchers reviewed each account and retained events supported by multiple sources. They also compared the documentary findings with physical evidence from cave ice and tree rings. This approach allowed the researchers to examine not only weather events but also how communities experienced and responded to environmental stress.
The records identified 55 exceptionally harsh winters during the 17th century. Thirty-six of them occurred between 1645 and 1700, although the period also included occasional hot summers and mild winters. Reports of excessive rainfall and other unusually wet conditions were more common than accounts of drought, though droughts were also documented.
Extreme weather had serious social consequences. Crop failures, sharp increases in food prices and widespread hunger were reported, while the conditions also favored the spread of diseases such as the plague. Climate stress compounded the effects of wars and political instability that were already placing pressure on local populations.
The researchers identify low solar activity, volcanic eruptions and changes in wind currents as possible contributors to regional cooling. However, the study could not determine the extent to which each factor influenced Transylvania’s climate. The authors emphasize that climate anomalies acted as additional pressures rather than being the sole causes of famine, epidemics or wider social disruption.
The study is titled “Climatic extremes and their social implications in 17th century Transylvania: An historical climate reconstruction” and was published in PLOS Climate in 2026.
Sources: Phys.org.