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Insufficient snowfall a cause of recessive glaciers

Lower winter precipitation has been one of the causes, along with global warming, behind melting glaciers over the past 150 years. These are the main findings of a study by researchers at the Laboratoire de glaciologie et géophysique de Grenoble/F and the Eidgenössische Technische Hochschule Zurich/CH, published in the Geophysical Research Letters.
Alpine glaciers rapidly increased in size during the Little Ice Age between 1550 and 1850, only to shrink again thereafter. Scientists had been puzzled by the strong period of growth between 1760 and 1830, given that average summer temperatures over that period were higher than in the 20th century. The study shows that this was due to winter precipitation, which decreased by 25% during the 19th century. Since this causal relationship does not apply to the 20th century, recessive glaciers are due largely to higher summer temperatures.
The researchers used a broad spectrum of data sources for their work. The oldest data pertains to the Clariden Glacier in Switzerland, which has been observed in detail since 1914. Scientists also analysed old maps, which accurately depicted the spread of the glaciers at the time. The study concludes that if alpine glaciers are to stabilise at their current levels in spite of a temperature increase of one degree centigrade, winter precipitation would have to increase by 300 to 400 mm a year.
Bibliography: Vincent, C. et al. "Solving the paradox of the end of the Little Ice Age in the Alps" in Geophysical Research Letters, Vol. 32, No. 9, 2005