Resumen de Estudio del glaciar Lange y su impacto debido al aumento de temperatura en la bahía Almirantazgo, isla Rey Jorge, Antártica

Diego Fernando Mojica Moncada, Carlos Cárdenas, Jhon Fredy Mojica Moncada, David Holland, Fabian Brondi Rueda, Cedomir Marangunic, Dalia C. Barragán Barrera, Andrés Franco Herrera, Gino Casassa

• español

  Al occidente de la Península Antártica se ha identificado una de las áreas de mayor calentamiento del hemisferio sur. Para caracterizar esta tendencia, se seleccionó el Glaciar Lange (GL) en la Isla Rey Jorge, con el fin de evaluar: 1) temperatura superficial y dinámica del GL utilizando estacas con sensores de temperatura; 2) espesor sumergido del GL y parámetros del mar a través de batimetría (BT) y 29 estaciones CTD frente al GL; 3) frente de glaciar (FG) utilizando BT y un Modelo Digital de Elevación (MDE); 4) cambio en la posición del FG usando MDE y datos históricos de su ancho; 5) flujo de Calving (QC). Los resultados mostraron que el 85 % de las temperaturas estuvieron por encima del punto de fusión de 0 °C (media = 5,0 ± 5,2 °C). Las estacas arrojaron una pérdida promedio de hielo de 9,3 ± 1,3 cm. La dinámica promedio del GL fue de 8,8 ± 1,5 m (0,40 ± 0,70 m/día), corroborado por imágenes de satélite Sentinel-1 (Offset Tracking = 0,43 ± 0,01 m/día). Seidentificó una intrusión de aguas externas más cálidas que las aguas residentes en la bahía del GL, lo cual desestabiliza la columna de agua debido a procesos de convección. Nuestros hallazgos en conjunto indicaron una fusión glaciar continua que aumenta su dinámica debido al aumento de temperatura, con un aporte de agua dulce a la Bahía del Almirantazgo. Según los resultados históricos y este estudio, el retroceso del GL se estimó entre 1956 y 2019 en 2.492 m.

• English

  The Intergovernmental Panel on Climate Change concludes that glaciers are sensitive indicators of climate change. Numerous studies have detected changes in the cryosphere during the last decades, where the thickness of the ice has decreased due to temperature increase, causing melting ice and sea-level rise. Antarctica is one of the greatest areas of interest due to its sensitivity and implications of warming over the cryosphere. Particularly, the Antarctic Peninsula and adjacent islands are areas where the greatest regional warming of the Southern Hemisphere has been identified. We selected the Lange Glacier on King George Island, Antarctica, in order to characterize the implications of Southern warming, from to description its dynamics, glacier front, temperature, melting and calving flux. Three temperature data loggers were installed in bamboo stakes at 200m distance each, and 200m from the north side on the surface of the glacier, which worked by 10 min for 22 days in the austral summer 2018-2019. Additionally, a bathymetric survey and 29 CTD stations were carried out in front of the glacier to determine frontal ice and water conditions. In order to determine the calving flux (QC), we assessed the glacier front using both bathymetric and a digital elevation model (DEM) data, we calculated the glacier front velocity using movement stakes data, and we assessed change in glacier frontal position using DEM and historical data of width glacier front. Our results showed that 85% of the temperatures were above the 0°C melting point, with average records of 5.0 ± 5.2°C. The stakes showed an average thickness of the ice loss of 9.3 ± 1.3cm. The average glacier movement registered by stakes was 8.8 ± 1.5m in the southeast direction equivalent to 0.40 ± 0.70m/day. This movement was corroborated by satellite images of Sentinel-1, which reported an Offset Tracking of 0.43 ± 0.01m/day. Survey bathymetric recorded depths from 10 to 220m, at the front of the glacier, which corresponds to ice thickness below sea level. External waters intrusion to the Lange bay were identified from the oceanographic stations. The external water is warmer than resident waters, destabilizing the water column through convection processes; as a result, the ocean influences the glacier, driving the subsurface glacier retreatment and basal melt. Our findings together indicate a continuous glacier fusion that increases its dynamics due to the increase of temperature, with a contribution of freshwater to the Admiralty Bay. Systematic monitoring is required to establish the direct implications of the LG climate change and water contributions to sea-level rise.