RECONSTRUCTIONG AND ANALYZING THE FLUCTUATIONS OF GLACIER ESPERANZA NORTE, WET ANDES, ARGENTINA, SINCE THE LITTLE ICE AGE

RUIZ, L.; MASIOKAS, M.; VILLALBA, RICARDO.

Valdivia

Simposio; II International Symposium "Reconstructing Climate Variations in South America and the Antartic Peninsula over the last 2000 years"; 2010

CECS

Glacier Esperanza Norte (also known as Glacier Túnel, 42°15′S, 72°10′W) is one of the largest glaciers in the north Patagonian Andes of Argentina and one of the very few glaciers with information about frontal fluctuations for the last centuries. This valley glacier is part of the Esperanza/Universo icefield and had in 2007 an area of 10.5 km2, a mean altitude of 1844 m, and a length of 4.94 km. The glacier is formed in a compound basin and has a land terminating, clean ice tongue. The longitudinal profile of the glacier is characterized by a relatively flat accumulation area and a steep ice fall in which the ablation area is currently located. Although basic data for this glacier has been included in the World Glacier Inventory, this information is presently inadequate for reconstructing the Equilibrium Line Altitude (ELA), length or areal variations. Here we present a reconstruction of glacier geometry and mass balance/glacier flux response for the past 400 years using an inverse glaciological approach based on dendrocronology data, historic photos, satellite images and a new geomorphology map made from field work and remote sensing data. Preliminary results indicate that the Little Ice Age maximum extent occurred in the early 17th century and has been followed by at least 20 glacier readvances or standstills embedded within an overall retreating. An analysis of the glacier’s response to changes in mass balance/glacier flux is performed in order to explain changes in the glacier’s geometry and the characteristics of the frontal moraines. This hypothesis is further explored with different ELA reconstruction methods in combination with climate reconstructions from other proxies.