Analysis of Glacier Recession in the Cordillera Apolobamba, Bolivia 1975-2010



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The tropical glaciers in the Bolivian Andes Mountains are small and respond quickly to changes in their climate. They are also a major source of freshwater year-round for nearby communities. Monitoring the glacial changes taking place in these glaciers has become increasingly important as they have been retreating over the past century. These glaciers are remote and the terrain treacherous making it potentially dangerous to gather data through field work. For this reason and because of advances in remote sensing technologies the use of satellite images has become the primary means to study these tropical glaciers in detail.

This research study focuses on the Cordillera Apolobamba range located on the Peruvian-Bolivian border. It is an example of the methodology applied to assess the area covered by glaciers in this and other regions around the world. Using Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) images from 1985 to 2010, as well as the Glacier Inventory of Bolivia, the glacier extents of the Apolobamba are mapped. From 1975 to 2010 the portion of the range located within Bolivia's border lost 110.76 km^2 of surface ice lowering its total area from 240.36 km^2 to 129.60 km2, a 46.08% reduction. From the 1985 to 2010 the entire Apolobamba range lost 102.72 km^2 of ice lowering its total area from 261.07 km^2 to 158.35 km^2, a 39.35% reduction.

An analysis of atmospheric conditions was conducted at the 500 hPa level for various climate variables using NCEP/NCAR reanalysis data. Between time period one (1975-1986) and two (1987-1995) the climate variables exhibiting a statistically significant change are air temperature with an increase of .165 degrees C and geopotential height with an increase of 2.967 m. Between time period two and three (1996-2005) the climate variables exhibiting a statistically significant change are freezing level with a 50.017 m increase, precipitation with an 60.604 mm/month decrease and wind velocity with an increase of .373 m/sec. According to the analysis conducted using the Oceanic Nino Index, the monthly sea surface temperatures exhibit no statistically significant change from 1975-2005.