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Snowline Altitude and Climate in the Peruvian Andes (5-17?S) at Present and during the Latest Pleistocene Glacial Maximum

TitleSnowline Altitude and Climate in the Peruvian Andes (5-17?S) at Present and during the Latest Pleistocene Glacial Maximum
Publication TypeJournal Article
Year of Publication1994
AuthorsFox, A. N., & Bloom, Arthur L.
JournalJournal of Geography
Volume103
Issue7
Pagination867-885
AbstractThe present snowline in the Peruvian Andes (5-17˚S), rises from as low as 4.7+/-0.1km on theeastern (windward) to more than 5.3+/-0.1km on the western (leeward) side of the central Andes.The effect of temperature on snowline altitude is isolated from the effect of precipition bysubtracting the altitude of the mean annual 0°C isotherm from the altitude of the snowline.This difference, defined as the normalized snowline altitude, increases with decreasing precipitation.The lowest late Pleistocene snowline rose from east to west and ranged in altitude from 3.2 to4.9 (+/-0.1) km. Both the present and lowest late Pleistocene snowlines indicate that moisture atboth times was derived principally from tropical easterly winds. An east-west precipitationgradient steeper than present is inferred for the eastern dopes of the central Andes from thesteeper late Pleistocene snowline gradient. Mean annual temperatures were 10+/-1.9°C coolerthat today at 3.52km, as calculated from a late Pleistocene snowline as much as 1.4+/-0.2 kmlower than today. Mean annual precipitation was 25 to 50% less than today along the easternside, and more than 75% less on the western side of the central Andes. These estimates oflower temperature and decreased precipitation are more extreme than previous estimates. Theyimply that the amount of glacial-age cooling eIsewhere, such as in western North America,may also have been underestimated by previous researchers because they did not adequatelyconsider the effect of reduced ice-age precipitation on snowline lowering.