How a giant volcanic eruption on a small Indonesian island on the Pacific Ring of Fire wreaked global havoc in the mid-13th century, causing summer to turn to winter and leaving millions starving.
Forensic techniques are used to investigate bizarre landscapes in the USA, Iceland and on the floor of the English Channel that were carved out by raging floods on a huge scale thousands of years ago.
Scientists examine The Great Hurricane of 1780, the most powerful event of its kind on record, to find out what made it so destructive and ask whether warming climates could create more monster storms.