Evolution récente des paramètres cryo-climatiques et des teneurs isotopiques des précipitations dans les Andes Boliviennes: La Paz et Glacier du Zongo

Abstract

Near La Paz, Bolivia, the main indicators of climatic trend are: (a) an increase in re-analysis temperatures at 500 hPa of 0.017°C year-1 between 1973 and 2004; (b) at Laica Cota meteorological station, between 1995 and 2004, a temperature rise of 0.03°C year-1 and a decrease in relative humidity of 0.6% year-1; and (c) an increase in rainfall δ18O of +0.26‰ year-1 as well as an increase in its deuterium excess of +0.1‰ year-1. One of the main consequences of this trend is a retreat of the Zongo Glacier front at 12 m year-1 between 1991 and 2004 (a decline of 2% per year of the glaciated area from 1997 to 2004, to 1.84 km2 in 2004). The simultaneous temporal data analysis shows that the variability of ENSO conditions has in-phase impacts at the infra-annual time scale on temperature, relative humidity, precipitation and glacier mass balance, and delayed consequences, over periods exceeding a year, for the isotopic ratio of Andean precipitation. © 2010 IAHS Press.