Black soot from 19th century homes and factories in Europe hastened the end of the Little Ice Age and caused glaciers in the Alps to retreat decades sooner than they would have otherwise, according to a new study. 
 
 The black carbon particles caused the snow to absorb more heat, speeding up the melting process. As a result, the glaciers beneath the snowpack were exposed earlier in the year, giving them more time to melt. And glacial ice melts faster than snow, because it is darker. 
 
 This story line explains why Alpine glaciers began to retreat around the year 1865, even though temperatures were cooler than they had been over the previous century and there was just as much rain and snow as before. An international team of scientists connected the dots in a study published Monday by Proceedings of the National Academy of Sciences. 
 
 Black carbon was “a byproduct of industrialization,” the scientists wrote. Emissions rose “dramatically” in the mid-1800s as coal was burned to heat buildings, power steam locomotives and fuel industrial activities. 
 
 Tiny black particles rose into the atmosphere and landed on the European Alps. The scientists examined some of them by examining ice cores from glaciers at several locations in the mountains. 
 
 At Monte Rosa in the Swiss-Italian Alps, the concentration of black carbon doubled in a roughly 20-year span. Before 1850, there were about 7 micrograms of black carbon per kilogram of glacier; by 1870, there were about 14 micrograms per kilogram. 
 
 At another site in the interior Swiss Alps, levels rose from 3 to 4 micrograms per kilogram in the 1860s to about 20 micrograms per kilogram by 1880. 
 
 The researchers created a detailed model to simulate glacier behavior based on the temperature and precipitation of the late 1800s. The model's results didn't match up to reality -- until the effects of black carbon were factored into the mix. Without them, the Alpine glaciers would have kept growing until about 1910, they wrote. 
 
 The heat effect of black carbon "is unique in explaining the Alps glacier retreat from the [Little Ice Age] in the mid-19th century while maintaining consistency with the temperature and precipitation reconstructions," they concluded. 
 
 Return to Science Now. ||||| Mountain peaks in the Bernese Alps protrude above the top of a hazy layer of air. Scientists have found convincing evidence that, beginning in the 1860s, soot sent into the air by a rapidly industrializing Europe caused the abrupt retreat of mountain glaciers in the European Alps. 
 
 Soot billowing across Western Europe during the Industrial Revolution may have caused the abrupt and unexpected retreat of European glaciers during a climatically cool period in the 19th century, new research suggests. 
 
 Mountain glaciers in the European Alps retreated by an average of nearly 0.6 miles (1 kilometer) between 1860 and 1930. This period falls at the end of Europe's so-called Little Ice Age, when temperatures dipped below average by about 1.8 degrees Fahrenheit (1 degree Celsius) across much of the continent. 
 
 Scientists have long struggled to identify a cause for this surprising retreat, but had been unable to find a suitable answer in the climate record. Now, researchers based at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have honed in on the potential anthropogenic — or human-induced — causes of the retreat. The researchers focused on the potential impact of particulate carbon, or soot, on snow melt. Soot was a major form of pollution at the time of the melt, given the prevalence of coal burning in that era. [In Images: Tracking a Retreating Glacier] 
 
 When soot settles on snow in large enough quantities, it creates a dark, heat-absorbent film on the otherwise reflective white surface of the snow. This causes the surface to absorb significantly more heat than it otherwise would, which eventually thins the snow down to the glacial ice that sits below the surface layer, causing further retreat. 
 
 To examine whether this effect would have been strong enough to induce the abrupt glacial retreat in the European Alps, the team analyzed ice cores collected from several European mountain glaciers and measured the levels of soot in various ice layers. The researchers used these measurements to estimate the quantities of soot that would have settled on glaciers lower in the Alps during the Industrial Revolution, and then entered this data into a computer model of glacial behavior. 
 
 They found that the soot could, in fact, have had a strong enough effect to heat and melt the snow at the rate recorded. 
 
 "This study uncovers some likely human fingerprints on our changing environment," Waleed Abdalati, a researcher at the University of Colorado and an author on the paper, said in a statement. "It's a reminder that the actions we take have far-reaching impacts on the environment in which we live." 
 
 The research appeared in the Sept. 2 issue of the journal Proceedings of the National Academy of Sciences. 
 
 Follow Laura Poppick on Twitter. Follow LiveScience on Twitter, Facebook and Google+. Original article on LiveScience. ||||| 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. 
 
 The glaciers melted an average one kilometer (0.6 miles) between 1860 and 1930. However, Europe’s average temperature dropped by nearly one degree Celsius (1.8 degrees F) during that same time. 
 
 “We must now look closer at other regions on Earth, such as the Himalaya, to study the present-day impacts of black carbon on glaciers,” said Georg Kaser, from the University of Innsbruck and co-author of the study. 
 
 IMAGE: Glacier Blanc in the Alps (Tom Corser, Wikimedia Commons)
– This much isn't in dispute: The glaciers of the European Alps retreated by an average of 0.6 miles between 1860 and 1930. But why, especially when the temperature of the continent itself actually cooled in the same period? Now a team of scientists thinks it has the answer, reports LiveScience: Soot from the Industrial Revolution. All those coal-burning factories and homes blanketed the mountains with thick black "particulate carbon," say researchers at NASA's Jet Propulsion Lab in Pasadena. They concluded as much after drilling ice cores from the Alpine glaciers and measuring remnants of the black stuff, reports Discovery, which explains the melting process thusly: "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." That exposed the glacier's underlying ice, which melted, too. If not for the soot, the glaciers would have kept expanding until about 1910, say the scientists, according to the LA Times.