There is a long-standing scientific debate about why the Alps glaciers began to retreat in the 1860s.
Scientists are now blaming black soot for the mid-1800s Alps glacier retreat. The soot, or black carbon, was sent into the air by the rapidly industrializing Europe between 1860 and 1930. The new report, which was published in the journal Proceedings of the National Academy of Sciences, may resolve a long-standing scientific debate about why the Alps glaciers began to retreat in the 1860s, years before global temperatures started increasing again.
The period in question is known as the end of the Little Ice Age, and marks when the large Alpine glaciers began retreating at a significant level, an average of nearly 0.6 mile. During the same time period, the temperatures in Europe cooled by nearly 1.8 degrees Fahrenheit. Because common sense says that glaciers retreat, or melt, when temperatures rise, scientists have long struggled with why the Alps glaciers retreated as temperatures cooled.
“Something was missing from the equation,” explains Thomas Painter, a snow and ice scientist at NASA’s Jet Propulsion Laboratory and the study’s lead author.
The team was determined to discover what that missing factor was.
By looking at history, they were able to see what was going on in Europe, home of the Alps, between 1860 and 1930. Europe was undergoing many changes as a result of industrialization, including an earnest effort to burn coal for homes, transportation and industry. As a result, black carbon and other particles were released into the atmosphere. When black carbon particles land on snow, they darken the surface. This melts the snow and exposes the underlying glacier ice to sunlight and warm air earlier in the year, leading to increased and faster melt.
By studying ice cores high on the Alpine mountains and then using computer models, researchers were able to determine that the soot accounted for the ice melting. In the computer model, none of the other factors significantly changed the melt rate; by adding in low-level coal pollution, the scientists could see the melt occurring.
“This study uncovers some likely human fingerprints on our changing environment,” said Waleed Abdalati, Director of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. “It’s a reminder that the actions we take have far-reaching impacts on the environment in which we live.”
Scientists now plan to examine the far-reaching effects of current coal burning on the environment and how that might continue to impact both global warming as well as the melting glaciers and ice sheets worldwide.
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