Glacier Fluctuations and Climate in the Cordillera Blanca, Peru

Abstract

With a total of 723 km 2 of glaciers (1970) the Cordillera Blanca includes the largest glacier-covered area in the tropics. The climate is characterized by relatively large daily and small seasonal temperature variations as well as by a distinct succession between a dry (May-September) and a wet season (October-April). Since the early 1970s an ablation stake network has been installed on the tongues of the glaciers Uruashraju and Yanamarey. The determination of the equilibrium-line altitude at each end of a wet season was possible, showing a fair correlation with temperature, but not with the precipitation records of the nearby climatological station Querococha. Mean ablation rates at the lowest parts of the glacier tongues are markedly higher during the wet season than during the dry season. Reasons are presumably to be found in the seasonal variation of cloudiness and air moisture rates. Terminus variations of four glaciers in the Cordillera Blanca have been monitored since the early seventies, earlier positions are reconstructed back to 1948 by vertical air photographs. For the glaciers Uruashraju and · Yanamarey the terminus positions of 1939 are known from an early map. The general retreat of glaciers in the Cordillera Blanca during the last five decades correlates with the global attitude of glaciers and especially with the attitude of glaciers in other tropical areas. Decreased recession rates with minor advances (I974-79 and 1985-86) are accompanied by lower annual temperatures and preceded and accompanied by years with relatively high annual precipitation sums.

Glacier recession and human vulnerability in the Yanamarey watershed of the Cordillera Blanca, Peru

“…Regular observations of glacial extent and climate variables associated with hydropower production by the Huaraz-based Peruvian Office of Glaciology and Lake Security date back to the 1970s (Carey 2005). While observations prior to this period are rare or discontinuous for the region, compilations of historical glacier maps and photographs quantify glacier mass balance changes over time (Ames et al 1989;Georges 2004;Kaser et al 1990;Kinzl 1942;Kinzl et al 1964;Morales Arnao and Hastenrath 1998). A program of routine surveying was established in 1968, and four target glaciers, including Yanamarey, were selected to monitor the magnitude of changes to these frozen reservoirs, providing a particularly important geographic database (Ames 1998;Francou et al 1995).…”

“…Between 1970 and1997, glacial coverage across the country declined by 22% and average temperatures have increased significantly since 1939 (CONAM 2001;Georges 2004;Kaser and Osmaston 2002;Vuille and Bradley 2000;Vuille et al 2008b). Because over 80% of freshwater available for downstream populations and ecosystems of the semi-arid tropics and subtropics originates in mountains, the recession of glaciers in these areas is particularly significant for the social and ecological systems that depend on these vital components of the hydrological regime (Messerli 2001).…”

Climate trends and glacier retreat in the Cordillera Blanca, Peru, revisited

“…Glaciers in the tropical Andes have witnessed a strong retreat during the last decades (e.g. Kaser et al, 1990;Hastenrath and Ames, 1995;Kaser and Georges, 1997;Georges, 2004;Mark and Seltzer, 2005;Silverio and Jaquet, 2005;Raup et al, 2007;Vuille et al, 2008a;Rabatel et al, 2013;Salzmann et al, 2013). Small glaciers in the tropical Andes at low altitudes show a more pronounced retreat, as the current equilibrium line altitude (ELA) climbed up towards the upper reaches causing a reduction or even loss of the accumulation area (Rabatel et al, 2013).…”

Monitoring tropical debris-covered glacier dynamics from high-resolution unmanned aerial vehicle photogrammetry, Cordillera Blanca, Peru

“…Most research in the Cordillera Blanca has addressed the entire range with a focus on glacier response to larger-scale climatic perturbations (Rabatel et al, 2013;Vuille et al, 2008) and their role in the hydrologic budget of the Rio Santa basin (Baraer et al, 2012;Juen et al, 2007;Kaser et al, 2010). A number of studies have investigated mass balance response of individual glaciers, though these have generally aggregated mass balance at the glacier scale (Hastenrath and Ames, 1995a, b;Kaser et al, 1990;Winkler et al, 2009). Few studies have documented glacier surface and volume changes at fine resolution in the Cordillera Blanca.…”