20th-Century Glacier Fluctuations in the Tropical Cordillera Blanca, Perú

The value of glacier fluctuations as indicators of climate change detection has been increasingly recognized in recent years. Tropical glaciers are of particular interest. The Cordillera Blanca in Perú (77°30′W, 9°S) is the largest glaciated area within the tropics. Its 20th-century fluctuations have been analyzed. The total ice coverage around 1990 was obtained using optical satellite data SPOT XS. Based on the 1990 results, inventories and estimates of the glaciation during the 20th century had to be corrected. The data in this paper illustrate the general ice retreat in the tropical Cordillera Blanca: 620 km2 in 1990, 660–680 km2 in 1970, and 800–850 km2 in 1930. The 1930 value documents the extent of glaciation shortly after an intense advance in the 1920s. The Little Ice Age extent is estimated as 850–900 km2. The ice recession during the 20th century was not constant but was concentrated in two periods. Strong ice retreat occurred in the 1930s and 1940s and intermediate retreat from the mid-1970s until the end of the century. The ice coverage at the end of the 20th century is considered to be slightly below 600 km2.