A change in climate may have triggered the decline and collapse of the Mayan city of Mayapán in the 15th century.
Science has made a strong case for the year 536 as being one of the worst in human history, a year punctuated by volcanic eruptions, drought, famine and plague - and a year long winter.
Greenland’s conditions were once similar to those of a greenhouse. Volcanoes swelled the land, constricted seaways and gigatonnes of greenhouse gases were released into the atmosphere.
Future extremes from the Indian Ocean will be acting on top of global warming, giving a double whammy effect, like the record-breaking heat and drought we saw in 2019.