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Area and volume loss of the glaciers in the Ortles-Cevedale group (Eastern Italian Alps): controls and imbalance of the remaining glaciers

DOI: 10.5194/tcd-7-267-2013

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Abstract:

A widespread loss of glacier area and volume was observed in the European Alps since the 1980s. Besides differences among various regions of the Alps, different responses characterize neighboring glaciers within the same region. In this study we describe the glacier changes in the Ortles-Cevedale group, the largest glacierized area in the Italian Alps. We characterize the drivers, the spatial variability and the main factors controlling the current loss of ice in this region by comparing glacier extents and snow covered areas derived from Landsat images acquired in 1987 and 2009. Glacier outlines were obtained from a band ratio with manual corrections and snow was classified from a near infrared image after topographic correction. The total glacierized area shrank by 23% in this period, with no significant changes in the mean altitude of the glaciers. The snowline is now 240 m higher than in the 1960s and 1970s. From the snow covered area of 2009, which fairly represents the extent of the accumulation areas over the last decade, we estimate that about 50% of the remaining glacier surfaces have to melt away to re-establish equilibrium with present climatic conditions. The average geodetic mass budget rate, calculated for 112 ice bodies by differencing two Digital Terrain Models (DTMs), ranged from 0.15 to 1.50 m w.e. a 1, averaging 0.68 m w.e. a 1. A correlation analysis of mass budgets vs. topographic variables confirmed the important role of the hypsometry in controlling area and volume loss of larger glaciers, while a higher variability characterizes smaller glaciers and glacierets, likely due to the increasing importance of local topo-climatic conditions.

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