Walter Silverio

Multi-temporal and multi-source cartography of the glacial cover of Nevado Coropuna Arequipa, Peru between 1955 and 2003

This study reports on the glacial cover evolution of the Nevado Coropuna between 1955 and 2003, based on Peruvian topographic maps and satellite images taken from the Landsat 2 and 5 multispectral scanner (MSS), Landsat 5 Thematic Mapper (TM) and Landsat 7 (ETM+). The normalized difference snow index has been applied to these images to estimate the glacierized area of Coropuna. The satellite-based results show that the glacier area was 105 ± 16 km2 in 1975 (Landsat 2 MSS), which then reduced to 96 ± 15 km2 in 1985 (Landsat 5 MSS), 64 ± 8 km2 in 1996 (Landsat 5 TM) and 56 ± 6 km2 in 2003 (Landsat 5 TM). Altogether, between 1955 and 2003, Coropuna lost 66 km2 of its glacial cover, which represents a mean retreat of 1.4 km2 year−1, that is, a loss of 54% in 48 years (11% loss per decade). The maximum rate of retreat occurred during the 1980s and 1990s, a phenomenon probably linked with the pluviometric deficit of El Niño events of 1983 and 1992.

Remote sensing of rapidly diminishing tropical glaciers in the northern Andes

This chapter presents an overview of some of the changes recently observed on glaciated areas in the tropical Andes of South America. Tropical glaciers are exceptional indicators of shifts in tropical climate, and the Andes are home to almost 99 % of the world’s tropical ice cover (Kaser et al. 1996). Many of the glaciated cordilleras in the northern Andes are mere remnants of what existed 50 years ago. Here we present a history of deglaciation of the Quelccaya Ice Cap in Peru, the largest body of ice in the tropics, which has lost approximately 30 % of its total area in the last 35 years; the Cordillera Blanca, a glaciated range in Peru, which has lost over 20 % of its area in the same period; glaciers in Colombia that have lost between 20–50 % or more of their area in the last few decades; Tres Cruces, a glaciated area in Bolivia, which has lost over half of its area; and one glacier in Venezuela that has lost over 90 % of its area. These changes are quite representative of overall glacier retreat throughout the tropical Andes.