Until now, it has been uncertain the extent to which Denmark was affected by the Late Antique Little Ice Age, a period of extreme cold and darkness between 536AD and 560AD, thought to have been caused by a series of major volcanic eruptions.  

But a new research study from the National Museum of Denmark, published in the Journal of Archaeological Science, has shown that the impact was massive, perhaps wiping out a large part of the population. The researchers studied the annual growth rings in more than 100 pieces of oak from the 6th century and found that for three years, between 539AD and 541 AD, there was barely any growth at all. 

“Many have speculated about it, but for the first time we can now demonstrate that perhaps the greatest climate disaster in human history affected Denmark – catastrophically,” Morten Fischer Mortensen, senior researcher at the National Museum, said in a press release. “If trees could not grow, nothing would have grown in the fields and in a society where everyone lived off agriculture, this must have had disastrous consequences.” 

He said this picture was backed up by parallel studies the museum is carrying out, which indicate a drastic decline in grain production, abandoned areas, and forests spreading into the former fields. 

Another recent study from the National Museum shows how agriculture changed to counter the harsher weather conditions, with a greater variety of crops grown to increase food security, including rye, which requires less sun than other cereals. 

“One can speculate whether the rye bread originates from this period, because historically rye has always been used for just that: bread. It’s an interesting thought that our love for rye bread might have been born out of a climate crisis, ” Mortensen said.

There has also been speculation that the climate catastrophe might be the origin of the Norse myth of the Fimbul winter, three years of darkness thought to herald the arrival of Ragnarok, the Viking apocalypse.