London, June 05 (ANI): Man-made global warming may not be the only reason behind the receding of the Great Aletsch Glacier, which is the largest Alpine glacier, in Valais, Switzerland.
The glacier has receded by more than two kilometers during the twentieth century.
However, Matthias Huss, a glaciologist at the University of Fribourg in Switzerland, claims that about half of the glacier loss in the Swiss Alps is due to natural climate variability.
"This doesn't question the actuality, and the seriousness, of man-made climate change in any way," Nature quoted Huss, as saying.
He added: "But what we do see is that current glacier retreat might be equally due to natural climate variations as it is to anthropogenic greenhouse warming."
Nature magazine reports, "Huss and his team managed to gather some 10,000 in situ observations that had been made over the past 100 years, and constructed three-dimensional computer models of 30 glaciers. By comparing a time series of daily melt, snow accumulation and ice and snow volume readings of the glaciers with a widely used index of the AMO, they teased out the impact of natural climate variability. Although the mass balance of individual glaciers varied, the long-term overall trend followed the pulse of the AMO.
"Since 1910, the 30 glaciers have lost a total of 13 cubic kilometres of ice - about 50 percent of their former volume. Brief periods of mass gain during cool AMO phases in the 1910s and late 1970s were outweighed by rapid losses during warm phases in the 1940s and since 1980, when temperatures rose and more precipitation fell as rain than as snow. The scientists believe that these changes are due to the combined effects of the natural cycle and anthropogenic global warming, which now seems to have a greater role than early in the twentieth century."
Georg Kaser, a glaciologist at the University of Innsbruck in Austria, said: "This is the first detailed attribution of known climate forces on glacier behaviour. Given the importance of glaciers to local water supply, this is essential information.
"The widespread idea that glacier retreat is the sole consequence of increased air temperature is overly simplistic. Glaciologists have known for more than 50 years that glaciers are sensitive to a variety of climate variables, not all of which can be attributed to global warming." (ANI)