Recession of Yanamarey Glacier in Cordillera Blanca, Peru, during the 20th century

Abstract For Yanamarey Glacier in Cordillera Blanca, Peru, mostly situated between about 5000 and 4600 m, maps of the surface topography at a scale of 1: 5000 obtained by terrestrial triangulation for 1973, 1982 and 1988 and by aerial photogrammetry for 1948 and 1962 are compared with the glacier boundaries from a 1939 map and an undated maximum extent inferred from moraine morphology. The glacier length decreased from the maximum, 2800 m to 1600 m in 1948. and to 1250 m in 1988, with an accompanying decrease in area from 17 × 10 5 to 10 × 10 5 and thence to 8 × 10 5 m 2 . The shrinkage of ice volume was 35 × 10 6 m 3 from the maximum to 1948. and 29 × 10 6 m 3 from 1948 to 1988. compared to a total remaining ice volume of about 25 × 10 6 m 3 in 1988. This quantitative assessment of mass-loss rates creates the observational basis for sensitivity studies of the climatic forcing.