In Norse mythology, Fimbulvetr (meaning Great Winter) commonly rendered in English as Fimbulwinter, is the immediate prelude to the events of Ragnarök (the battle between Gods and Ice-giants that will occur at the end of the world).

It is theorised that Fimbulwinter may have occurred in 536AD, when volcanic activity caused tonnes of ash to blot out the sun for 18 months, plunging the Northern Hemisphere into a long, harsh winter that caused ripples across 150 years of history..

2500 years later, it's happening again...