As the Industrial Revolution began to pick up steam in Europe, the glaciers of the Alps retreated. However, the average temperature of the continent cooled at that time, which created a glacial melting mystery for scientists.
"Something was missing from the equation," Thomas Painter, of NASA's Jet Propulsion Laboratory said in a press release. Painter led a team of scientists that recently found a clue identifying the Alpine glacier's attacker.
Soot in the smoke billowing from coal-burning factories, steam engines and other sources seems to have sullied the white glaciers, causing them to melt, according to Painter's study published in the Proceedings of the National Academy of Sciences.
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Painter's team discovered the filthy fingerprint of Industrial Age soot in ice cores drilled from Alpine glaciers. The soot probably settled on the snow overlaying the glaciers and caused the insulating blanket of snow to heat up like a black car in the sun. After the snow melted, the underlying ice of the glacier was left open to the sunlight and melted as well.