French geologist Robert Delmas leans back triumphantly in his lab chair. It’s 1992 and he has been examining a 550-year-old ice core looking for evidence that might reveal why the world was tormented by natural disasters and unusual weather phenomena in the mid-1400s. And he has found what he was looking for: close layers of sulfuric acid in the ice core suggest a massive volcanic eruption, one that veiled the world in a cloud of ash and sulfur.
The eruption was clearly one of the most devastating events in recorded history. The energy discharge would have been equivalent to some 2,000,000 nuclear bombs, the explosion so loud that it could have been heard 2000km away. Ash would have rained from the sky, tsunamis striking coasts, the sunlight blocked out for several years.
To people in the 1400s, the destruction must have seemed like punishment from on high. In the resulting famine, tens of thousands starved to death, yet the cause would have been unknown to most of them. To Robert Delmas and the other geologists, it was now obvious that a volcano was responsible. But which volcano?
The search for that answer turned into a major detective assignment. The search has taken scientists around the world for three decades – from volcanic islands in ice-covered Antarctica to submarine craters in the tropics. Clues from history have also been re-examined, from analyses of old portrait frames to accounts of Swedish summers that never happened, and Polish city-dwellers who had to paddle through flooded
