Stockholm (AP) — The writing on a famous Viking-era runestone may reflect fears of an approaching climate disaster in 9th century Scandinavia, according to new research by a team of Swedish academics.

The Rok stone, located near Lake Vattern in central Sweden, carries what is believed to be the longest known runic inscription in the world. It consists of more than 700 runes, the letters of old Germanic language alphabets.

Researchers have long thought the 5-ton, roughly 2.5-meter (8-feet) tall Rok stone was raised as a memorial to a dead son and the writing on it related heroic tales of Viking kings and the battles they fought.

But four Swedish academics who teamed up to interpret the inscription postulated in a paper published this week that several passages dealt with a natural threat, not a military battle.

“We believe it talks about a cosmic balance,” University of Goteburg Professor Per Holmberg, who led the study, said.

“Maybe we’ve focused too much on the importance of military power, but maybe the religious power to keep the cosmos together was more important.” Holmberg added.

A reference on the stone to the “death of the sun nine generations ago” could refer to the extreme climate cooling in the years 535-536 that caused worldwide crop failures and famine.

“The powerful elite of the Viking Age saw themselves as guarantors for good harvests,” Olof Sundqvist, a professor of religious history at Stockholm University, said. “They were the leaders of the cult that held together the fragile balance between light and darkness."

Norse mythology describes a Fimbulwinter, or brutal winter, preceding the end of the world. In the 9th century there were reasons for the Vikings to fear one was coming and wipe out all life on Earth, according to Bo Graslund, an archaeology professor at Uppsala University, said.

“Before the Rok runestone was erected, a number of events occurred which must have seemed extremely ominous: a powerful solar storm colored the sky in dramatic shades of red, crop yields suffered from an extremely cold summer, and later a solar eclipse occurred just after sunrise. Graslund said. "Even one of these events would have been enough to raise fears of other Fimbulwinter.”

_

Follow full AP coverage at https://www.apnews.com/Climate