In the 16th century, Europe and the North Atlantic went through a strange climate episode called the Little Ice Age. It was a time of paradoxes. In Western Europe, the chill of the Little Ice Age deepened, crops withered, and rivers froze over. But in Transylvania, a different climate story unfolded — one marked by scorching summers, devastating droughts, and, later, relentless rain.

The clues to this forgotten climate saga weren’t discovered in ice cores or tree rings but rather in human memories — diaries, parish registers, and monks’ chronicles. The findings suggest that while Western Europe shivered, Transylvania burned — at least for the first half of the century. Only later did the region succumb to the cooling effects of the Little Ice Age.

These centuries-old diaries tell a tale that’s very relevant to us today.

A Delayed Little Ice Age?

In principle, the Little Ice Age is well known. For decades, scientists have studied this period of global cooling between the 14th and 19th centuries. In Western Europe, glaciers advanced, harvests failed, and winter fairs were held on the frozen Thames. Unlike a true ice age, it did not involve massive glaciation but rather a series of colder-than-average centuries that profoundly affected human societies, ecosystems, and weather patterns. But it wasn’t the same everywhere.

“The first half of the 16th century was marked by extreme heat and prolonged droughts,” said Tudor Caciora, one of the study’s authors. “This makes us believe that the Little Ice Age could have manifested itself later in this part of Europe.”

Meanwhile, in Transylvania, historical records paint a different picture.

“The springs dried up, and the rivers dwindled to mere trickles. Livestock fell in the fields, and the air was thick with despair as the people gathered in processions, praying for rain,” one passage reads. “This vivid account underscores the emotional and spiritual dimensions of living through climatic extremes,” writes Tudor Caciora, from the University of Oradea, Romania.

These records align with findings from Western Europe, where 1540 is also known as the “year without water.” But unlike Western Europe, where cold set in shortly afterward, Transylvania’s heatwaves and droughts persisted well into the 1570s.

Disaster after disaster

Located in central Romania, Transylvania has cold winters and warm summers. Its inhabitants go through a broad range of temperatures within a year, but in the 16th century, things took a dramatic turn.

Poor harvests and scorching heatwaves led to 23 years of famine in the region. In some cases, starvation was so severe that people resorted to eating grass. For instance, one diary describes a famine where people were “losing their minds because of hunger,” resorting to eating herbs, tree bark and carrion. Skeletal corpses were described as having grass in their mouths.

Then came the plagues.

Over 30 years of plague outbreaks were recorded, often following food shortages. “The poor harvests of the rainy years and the atypical weather from the fall of 1553 and the winter towards 1554, sunny as if it were spring, caused the malnutrition that facilitated the terrible plague epidemic of 1553–1554,” the authors note.

As the century wore on, Transylvania’s climate started changing. By the 1590s, heavy rains replaced drought, leading to devastating floods. Historical sources describe years of almost ceaseless downpours, washing away entire villages. To top it all off, swarms of locusts, fueled by prolonged droughts, stripped fields bare in at least nine recorded years, worsening food shortages.

A warning from the past

While nature’s archive — glaciers, tree rings, and sediment — provides a long-term record of past climate change, “society’s archive” reveals something just as valuable: how people experienced and responded to those changes. It’s not objective, but it offers a more nuanced, human-centric view of climate history, beyond raw temperature data.

Yet, using historical documents comes with challenges. Few people in the 16th century were literate, and even fewer had the means to record daily weather. The records that survive are often biased toward extreme events. No one wrote about an average summer, only the unbearable ones.

Even so, this gives a stark warning to our current times, where climate change is far more severe than in the Little Ice Age, which was a natural transition.

First, it underscores how abrupt and severe climate shifts can be. The transition from prolonged droughts to years of flooding shows how unpredictable regional climate can be — something modern climate models warn about in our own warming world.

Second, it highlights the deep societal impacts of climate change. Food shortages, disease outbreaks, and mass displacement are not new — they have happened before, and they will happen again.

The study was published in the journal Frontiers in Climate.