In the year 536, the sun went dark and did not return to normal for a year and a half. Temperatures plummeted, crops failed and floods ravaged the land. But what had caused this devastating event? Through studying ice cores in the Antarctic, scientists traced the source to a huge volcanic eruption. The massive cloud of material it ejected was transported by jet streams right around the globe, causing the sun to dim and the earth to cool by several degrees. Civilisations around the planet were thrown into turmoil and the course of history changed forever. And the most terrifying thing about this event is that one day it will happen again…