While searching through historical archives to find out more about the 15th-century climate of what is now Belgium, northern France, Luxembourg, and the Netherlands, Chantal Camenisch noticed something odd.
“I realised that there was something extraordinary going on regarding the climate during the 1430s,” says the historian from the University of Bern in Switzerland.
Compared with other decades of the last millennium, many of the 1430s’ winters and some springs were extremely cold in the Low Countries, as well as in other parts of Europe. In the winter of 1432-33, people in Scotland had to use fire to melt wine in bottles before drinking it. In central Europe, many rivers and lakes froze over. This affected food production in many parts of Europe.
“For the people, it meant that they were suffering from hunger, they were sick and many of them died,” says Camenisch.
She joined forces with Kathrin Keller, a climate modeller at the Oeschger Centre for Climate Change Research in Bern, and other researchers, to find out more about the 1430s climate and how it impacted societies in northwestern and central Europe. Their results are published today in Climate of the Past, a journal of the European Geosciences Union.
They looked into climate archives, data such as tree rings, ice cores, lake sediments and historical documents, to reconstruct the climate of the time.
“The reconstructions show that the climatic conditions during the 1430s were very special. With its very cold winters and normal to warm summers, this decade is a one of a kind in the 400 years of data we were investigating, from 1300 to 1700 CE,” says Keller.
There have been other cold periods in Europe’s history. In 1815, the volcano Mount Tambora spewed large quantities of ash and particles into the atmosphere, blocking enough sunlight to significantly reduce temperatures in Europe and other parts of the world. But the 1430s were different, not only in what caused the cooling but also because they hadn’t been studied in detail until now.
The climate simulations ran by Keller and her team showed that these conditions were due to natural variations in the climate system, a combination of natural factors that occurred by chance and meant Europe had very cold winters and normal to warm summers.
Regardless of the underlying causes of the odd climate, the 1430s were “a cruel period” for those who lived through those years, says Camenisch. In some cities, such as Basel, Strasbourg, Cologne or London, societies adapted more constructively to the crisis by building communal granaries that made them more resilient to future food shortages.
In the 1430s, people had not been exposed to such extreme conditions before and were unprepared to deal with the consequences. “Our example of a climate-induced challenge to society shows the need to prepare for extreme climate conditions that might be coming sooner or later,” says Camenisch.