Mass balances 2007/12 of four small glaciers at Central Andes, Argentina-Chile.

CABRERA, G. A.; .LEIVA, J. C.

Fairbanks, Alaska

Simposio; International Symposium on Glaciers and Ice Sheets in a Warming Climate; 2012

International Glaciological Society

A five-year mass-balance series are presented for four glaciers of the central Andes of Argentina and Chile between 4900 and 5500 m a.s.l. On the Argentinian side, Jáchal river basin, the glaciers are Conconta (9 ha) and Brown (19 ha), headwaters of Conconta Creek (29°59´ S, 69°38´ W) in Cordillera Colangüil; Los Amarillos (99 ha) on the international border summit, headwaters of Turbio and Los Amarillos streams; and Amarillo (24 ha), very close to the last before mentioned, on the Chilean side, Huasco river basin, at the headwaters of Tránsito Creek. The study area also has many glacierets increasingly receding, some of which will disappear in the near future; one of them extinguished in 2011. Mass balances were obtained by the glaciological method, with one spring field mission to get the winter balance and another one in the autumn to get the summer balance, every year. The net annual mass balances have been negative for all the glaciers during the study period. The weighted mass-balance means for the two Colangüil glaciers are ?64 (2007/08), ?101 (2008/09), ?118 (2009/10) and ?171 cm w.e. (2010/11); and for the two glaciers on the international border are ?21 (2007/08), ?75 (2008/09), ?102 (2009/10) and ?75 cm w.e. (2010/11). The 4 year cumulated balances (2007/11) are ?454 cm w.e. as average for the two Colangüil glaciers and ?273 cm w.e. as average for the other two glaciers. Taking into account the areas of 28 ha and 123 ha, this represents a mass loss of 1.46 and 3.40 million tons of water, respectively. The accumulated mass variation of each glacier system, calculated with the glacier volumes obtained by GPR surveys in 2008, is ?13.2% for the Colangüil glaciers and ?22% for the higher ones. The balance stakes displacement was measured. At the central part of Conconta Glacier the stake displacement was 3 m between the spring and autumn field missions 2009/10. The following year this displacement duplicates to 7 m. The displacements at the central part of Brown Glacier were, respectively, 8 and 22 m, showing in this way its greater activity. At the higher glaciers, the displacements were smaller: 1?2 m at Amarillo Glacier and 3?4 m at Los Amarillos Glacier, which shows its greater activity also in its morphology. The mass-balance results were compared with the WGMS global sample and few significant differences were found. The strong negative balances are discussed as local evidence of the current warming climate.