Paul Scherrer Institute researchers have shown PSI together with colleagues from China and the United States, that global warming is not solely responsible for the melting of glaciers in the Himalayas. Even Russia, which is deposited on the glacier, is helping. It leaves the surface are dark, after which can be heated by solar radiation and melts the ice faster. The soot produced when oil or wood is burned, the wind then carries it to the Himalayas. The influence of algae on the glacier is under investigation by the PSI.
For his work, researchers have investigated an ice core has been drilled on the northern slope of Mount Everest, and therefore could look past the glacier until about 1860 and shows how the amount of soot in the past decades has increased. Even if global warming is the main reason for the melting of glaciers could also be delayed if the soot emissions are reduced. The results of this study are published in the journal Geophysical Research Letters.
Paul Scherrer Institute researchers have discussed with their U.S. colleagues and China is another source that contributes to the melting of glaciers: the soot deposits. The soot formed during the incomplete combustion of fossil fuels like coal and oil, and wood and other biomass. Carried by the wind, reached into the highest regions of the Himalayas, where it is deposited on the surfaces of glaciers and becomes darker, so get hotter by the rays of the sun. How strong is this effect and whether it is caused by human activities, but is not yet clear.
Last soot content in the glacier ice
For their work, researchers have investigated an ice core that had been taken on the northern flank of Mount Everest more than 6,500 meters. In the 108 meters of drilling time can be compressed layer upon layer of snow in recent years - until 1860, so go back the details about each of the trace elements mentioned in the snow. So much so, and that variations can be made visible in different years. For measurement, the researchers used a new laser device can very accurately the amount of carbon black, the black share of black coal, found in a sample.
Since 1975, more soot in the Himalayas
Tests have shown for the first time how changes in the amount of soot in the Himalayas since pre-industrial. The result is soot contributes about three times since 1975 in a glacier melting in the pre-industrial era. It has been found that the amount of soot deposits in the single year varies widely - is in winter and spring is greatest when winds move from the southwest of Russia from South Asia and the Middle East to the Himalayas. In summer, the amount of soot is much lower - the soot is removed by monsoon rain in the atmosphere. While researchers have observed in 1990, an increase in soot content, which remains more or less constant since then. That could be a sign that Russia, Eastern Europe and the former Soviet Union, the areas where emissions have fallen significantly in recent decades, until it can be transported to the Himalayas. Due to prevailing westerly winds almost no proven Russ on Everest in China's industry.
The soot and dust?
The wind carries the mountains not only in Russia but also the rock dust from the surrounding arid regions. Fortunately, the researchers show that soot contributes significantly more heat than ice and dust that the amount of dust in the Himalayas has not changed since 1860, so that soot is probably the man of dust is not. "In the winter months, Russia contributes about the same strength to the melting of glaciers and global warming. A measure that would reduce soot emissions may therefore contribute to reduce the glaciers are melting." said Margit Schwikowski , director of the research project at PSI. "So far we have demonstrated the role of soot in the melting of glaciers in the Himalayas. What role for glaciers in Switzerland, is the subject of an ongoing research project. Also assess the degree of algae contribute to the dark surface of the glacier at the end of summer. "
Text: Paul Piwnicki
About ISP
The Paul Scherrer Institute, builds and operates major facilities, complex research and provide the scientific community nationally and internationally available. Prepared by the solid-state research and material sciences, elementary particle physics, biology and medicine, energy and environmental research. With 1,400 employees and an annual budget of around 300 million francs, is the largest research institute in Switzerland.
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