Major droughts ahead of famine and Black Death in 14th century have parallels with climate crisis today, researchers say

A 14th century climate transition period following centuries of warm European weather and before the onset of the so-called Little Ice Age bears a striking resemblance to some of today’s weather phenomena, scientists have said.

A new study by a team in Leipzig, Germany, is based on research combining physical climate data recorded in tree rings and sediment cores, along with written historical sources from the time, which together paint a vivid picture of how conditions changed and what the impacts were.

Starting in around 950AD and lasting for over 300 years, a climate anomaly known as the Medieval Warm Period raised temperatures in Europe, before a brief period of transition led to the onset of the Little Ice Age when global temperatures fell.

As the warm period drew to an end, severe droughts between 1302 and 1307 in Europe preceded a prolonged wet and cold phase during the 1310s which resulted in the great famine of 1315-21.

The scientists have suggested the 1302-07 weather patterns have marked similarities to the 2018 weather anomaly, in which continental Europe experienced exceptional heat and drought.

The research team, from the Leibniz Institutes for the History and Culture of Eastern Europe (GWZO) and Tropospheric Research (TROPOS), said both the medieval and the recent weather patterns resemble the stable weather patterns which have occurred more frequently in Europe since the 1980s due to the increased warming of the Arctic.

They said such transitional phases in the climate are always characterised by periods of low variability, in which weather patterns remain stable for a long time.

But after this period of relative climate stability marked by the droughts, a phase of rapid climate change began in around 1310. The weather during this tumultuous decade became known as the “Dantean Anomaly" after the contemporary Italian poet and philosopher Dante Alighieri, famous for his vivid depictions of Hell.

Weather historian Neville Brown described the conditions as “quasi-continuous cyclonic circulation of moist air of polar origin”, in which grey skies and heavy rain soaked the landscape causing extensive flooding and washing away fertile soils.

The result was the Great Famine (1315-1321), which is considered the largest pan-European famine of the past millennium.

This was followed a few years later by the Black Death (1346-1353), the most deadly pandemic in human history, which wiped out about a third of Europe’s population, and lingered for centuries after.

The meteorological records and the socio-economic history detailed in written sources have not previously been studied together, and the scientists say their approach, which currently focuses on northern Italy, southeastern France, and east central Europe, provides new insight into the vulnerabilities of populations at the time.

“We want to show that historical climate change can be reconstructed much better if written historical sources are incorporated alongside climate archives like tree rings or sediment cores,” said Dr Martin Bauch from the GWZO.

“The inclusion of humanities research clearly contributes to a better understanding of the social consequences of climate change in the past and to drawing conclusions for the future.”

The human records provide information on wine and wheat production, the number and location of historical city fires, and economic data revealing trade and market conditions, all of which are influenced by the climate.

The researchers said while the summer of 1302 was still very rainy in central Europe, several hot, very dry summers followed from 1304 onwards.

From the perspective of climate history, this was the most severe drought of the 13th and 14th centuries.

“Sources from the Middle East also report severe droughts. Water levels in the Nile, for example, were exceptionally low. We therefore think that the 1304-06 drought was not only a regional phenomenon, but probably had transcontinental dimensions,” said Dr Thomas Labbé from the GWZO.

Based on the recorded effects, the team reconstructed the historical weather conditions between the summer of 1302 and 1307.

Through evaluations of the 2018 drought and similar extreme events, it is now known that, in such cases, a so-called “precipitation seesaw” usually prevails.

This is where there is extremely high precipitation in one part of Europe and extremely low precipitation in another.

“This is usually caused by stable high and low pressure areas that remain in one region for an unusually long time,” according to meteorologist Dr Patric Seifert from TROPOS, who was responsible for reconstructing the large-scale weather situations for the study.

He added: “In 2018, for example, very stable lows lay over the North Atlantic and southern Europe for a long time, which led to heavy precipitation there and an extreme drought in between in central Europe.”

The analysis of the possible large-scale weather situations indicates that between 1303 and 1307, a strong, stable high pressure system predominated over central Europe, which explains the extreme drought in these years.

The research team said their analysis of the historical weather in Europe could inform the ongoing discussion about how the climate crisis affecting the Arctic is impacting weather patterns in Europe.

In recent decades, the Arctic has warmed more than twice as much as other regions of the world.

This phenomenon, called “Arctic amplification”, is also being studied by a team of academics led by the University of Leipzig.

One theory assumes that the disproportionate warming of the Arctic causes the temperature differences in mid-latitude areas to decrease.

The effect of this is to also reduce the extent of the sharp contrasts between warm and cold fronts of air which cause meteorological disturbances.

As a result, according to a common hypothesis, weather patterns may persist longer than in the past.

"Even if it was a phase of cooling in the Middle Ages and we are now living in a phase of man-made warming, there could be parallels,” Dr Seifert said.

“The transitional period between two climate phases could be characterised by smaller temperature differences between the latitudes and cause longer-lasting large-scale weather patterns, which could explain an increase in extreme events.”

In their study, the researchers recorded a noticeable coincidence between the periods of drought and urban fires.

Fires were a major danger for the densely constructed, largely wooden, cities in the Middle Ages, where there were no fire brigades like there are today.

The best documented fire between 1302 and 1307 was probably in Florence, where over 1,700 houses burned on 10 June 1304.

Sources for both Italy and France showed a correlation between extreme drought and fires at the same time.

“We think our analysis is the first to find a correlation between fires and droughts over a two-hundred-year period,” said Dr Bauch.

“Large urban fires usually followed droughts by a year. The wooden structures in medieval houses did not dry out immediately. But once they did, they ignited very easily.”

Contemporaries were also aware of the connection between drought and fire: during dry periods, citizens were obliged to place buckets of water next to their front doors as a primitive sort of fire extinguisher, to be kept available at all times.

It was only later that municipalities organised fire brigades, for example in Florence around 1348.

Major infrastructural measures in response to the droughts have survived in the cities of northern Italy: Parma and Siena invested in larger, deeper wells, and Siena also bought a harbor on the Mediterranean coast, which it expanded after the drought years of 1302-04 in order to be able to import grain and become less dependent on domestic production.

“According to our analysis, the drought of 1302-1307 was a once-in-a-century event with regard to its duration,” said Annabell Engel from GWZO.

“No other drought reached these dimensions in the 13th and 14th centuries. The next event that came close was not until the drought of 1360-62, which stretched across Europe and for which there indications in the historical record in Japan, Korea, and India.”

While numerous studies have already documented strong fluctuations in the 1340s, shortly before the plague epidemic, the first decade of the 14th century has been the focus of little research so far.

The Leibniz researchers have now been able to show for the first time that exceptionally dry summers between 1302 and 1304 to the south of the Alps and 1304 and 1307 north of the Alps were the result of stable weather conditions and disparately distributed precipitation.

The study thus sheds new light on the first years of the 14th century with its dramatic changes and draws a link to modern climate changes.

“However, it is difficult to draw conclusions about future climatic developments in the 21st century from our study,” the researchers said.

“While climate fluctuations in the 14th century were natural phenomena, in the modern age, humans are exerting artificial influence on the climate, as well.”

The research is published in the journal Climate of the Past.