New insights into the decadal variability in glacier volume of a tropical ice cap, Antisana (0°29' S, 78°09' W), explained by the morpho-topographic and climatic context

• Published in: The Cryosphere
• Main Authors: Basantes-Serrano, Rubén, Rabatel, Antoine, Francou, Bernard, Vincent, Christian, Soruco, Alvaro, Condom, Thomas, Carlo Ruíz, Jean
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU]Sciences of the Universe [physics]; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Ice cap; The Cryosphere
• Online Access: https://insu.hal.science/insu-03859250; https://insu.hal.science/insu-03859250/document; https://insu.hal.science/insu-03859250/file/tc-16-4659-2022.pdf; https://doi.org/10.5194/tc-16-4659-2022

International audience We present a comprehensive study of the evolution of the glaciers on the Antisana ice cap (tropical Andes) over the period 1956-2016. Based on geodetic observations of aerial photographs and high-resolution satellite images, we explore the effects of morpho-topographic and climate variables on glacier volumes. Contrasting behaviour was observed over the whole period, with two periods of strong mass loss, 1956-1964 (−0.72 m w.e. yr −1 ) and 1979-1997 (−0.82 m w.e. yr −1 ), and two periods with slight mass loss, 1965-1978 (0.10 m w.e. yr −1 ) and 1998-2016 (−0.26 m w.e. yr −1 ). There was a 42 % reduction in the total surface area of the ice cap. Individually, glacier responses were modulated by morpho-topographic variables (e.g. maximum and median altitude and surface area), particularly in the case of the small tongues located at low elevations (Glacier 1, 5 and 16) which have been undergoing accelerated disintegration since the 1990s and will likely disappear in the coming years. Moreover, thanks to the availability of aerial data, a surging event was detected on the Antisana Glacier 8 (G8) in the 2009-2011 period; such an event is extremely rare in this region and deserves a dedicated study. Despite the effect of the complex topography, glaciers have reacted in agreement with changes in climate forcing, with a stepwise transition towards warmer and alternating wet-dry conditions since the mid-1970s. Long-term decadal variability is consistent with the warm-cold conditions observed in the Pacific Ocean represented by the Southern Oscillation index.