PASADENA, California - Scientists have wondered about the apparent contradiction for years. Temperatures were dropping in Europe during the end of the late 1800s, during what is called "the Little Ice Age," but glaciers in the mountains were steadily receding. How was that possible?
NASA scientists now believe they've solved the mystery. Soot, thrown into the air by a rapidly industrializing Europe, may have settled on the snowy mountainsides. The black soot, composed of carbon from coal, would have caused those mountains to absorb more of the sun's heat, the theory goes. The resulting snow melt exposed the ice underneath to the spring and summer sun, causing the glaciers' retreat.
NASA scientists published their research involving sophisticated computer models this week in the Proceedings of the National Academy for Sciences.
The Little Ice Age, a cooler period between the 14th and 19th centuries, featured both expanded mountain glaciers and a drop in temperatures in Europe of nearly 1.8 degrees Fahrenheit (1 degree Celsius). But between 1860 and 1930, while temperatures continued to drop, large valley glaciers in the Alps retreated by an average of nearly 0.6 mile."Something was missing from the equation," said Thomas Painter, a snow and ice scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., who led the study. "Before now, most glaciologists believed the end of the Little Ice Age came in the mid-1800s when these glaciers retreated, and that the retreat was due to a natural climatic shift, distinct from the carbon dioxide-induced warming that came later in the 20th century. This result suggests that human influence on glaciers extends back to well before the industrial temperature increases."