An eruption in 1257—the biggest in the last 3,700 years—was so vast that it left its mark at opposite ends of the Earth and exacted a profound short-term impact on the climate, including a "year without a summer." Its chemical signature appears in Arctic as well as Antarctic ice, while in Europe, medieval records discuss plunging temperatures and ruined harvests, the BBC reports. Now, experts believe they've figured out which volcano was responsible—and it's in Indonesia. The Samalas Volcano, on the country's Lombok Island, isn't so imposing today: The area is dominated by a crater lake. In order to find the volcano, "We conducted something similar to a criminal investigation," a researcher says.
"We didn't know the culprit at first," he says, "but we had the time of the murder and the fingerprints in the form of the geochemistry in the ice cores, and that allowed us to track down the volcano responsible." Chemical traces in the ice seem to match data from the Lombok region, ranging from material ejected to tree rings to historical records of a local kingdom that fell around the same time. "We had geologists, geochemists, geographers, historians, radiocarbon-dating specialists, and many others—all these researchers from different specialties to combine facts," the researcher tells National Geographic. (Another fascinating find: Scientists recently found an underwater volcano—the size of Arizona.)