Heterogeneous and rapid ice loss over the Patagonian Ice Fields revealed by CryoSat-2 swath radar altimetry

Abstract

The Northern and Southern Patagonian Ice Fields (NPI and SPI) in South America are the largest bodies of ice in the Southern hemisphere outside of Antarctica and the largest contributors to eustatic sea level rise (SLR) in the world, per unit area. Here we exploit swath processed CryoSat-2 interferometric data to produce maps of surface elevation change at sub-kilometer spatial resolution over the Ice Fields for six glaciological years between April 2011 and March 2017. Mass balance is calculated independently for nine sub-regions, including six individual glaciers larger than 300 km2. Overall, between 2011 and 2017 the Patagonian Ice Fields have lost mass at a combined rate of 21.29 ± 1.98 Gt a−1, contributing 0.059 ± 0.005 mm a−1 to SLR. We observe widespread thinning on the Ice Fields, particularly north of 49° S. However the pattern of surface elevation change is highly heterogeneous, partly reflecting the importance of dynamic processes on the Ice Fields. The Jorge Montt glacier (SPI), whose tidewater terminus is approaching floatation, retreated ~2.5 km during our study period and lost mass at the rate of 2.20 ± 0.38 Gt a−1 (4.64 ± 0.80 mwe a−1). In contrast with the general pattern of retreat and mass loss, Pio XI, the largest glacier in South America, is advancing and gaining mass at 0.67 ± 0.29 Gt a−1 rate.