Distributed ice thickness and glacier volume in southern South America

Abstract

14South American glaciers, including those in Patagonia, presently contribute the largest amount of by this study will facilitate future studies of ice dynamics and glacier isostatic adjustment, and will 34 be important for projecting water resources and glacier hazards. Garibaldi, are presently displaying a positive mass balance (Schaefer et al., 2015). The general and 53 dominant trend of ice mass loss is manifest in pronounced glacier recession (Davies and Glasser, 54 2012) and the largest contribution to sea level rise per unit area in the world (Ivins et al., 2011; 55 Mouginot and Rignot, 2015; Willis et al., 2012). Indeed this sea level contribution is ~ 10 % of that 56 from all glaciers and ice caps worldwide (Rignot et al., 2003). Over the next two centuries, mass loss 57 from these glaciers has implications for sea level rise (Braithwaite and Raper, 2002; Gardner et al., 58 2013; Glasser et al., 2011;Levermann et al., 2013), for increased hazards from glacial lake outburst 59 floods (Anacona et al., 2014; Dussaillant et al., 2009;Harrison et al., 2006; Loriaux and Casassa, 60 2013), and for water resources. 62Recent analysis of southern South America glaciers has yielded data regarding glacier area, areal and 63 volume change since the Little Ice Age (LIA) (Davies and Glasser, 2012; Glasser et al. 2011), ice 64 surface velocity (Rivera et al., 2012; Jaber et al., 2013; Mouginot and Rignot, 2015), surface mass 65 balance (Koppes et al., 2011; Mernild et al., 2015; Schaefer et al., 2015; Willis et al., 2011) and 66 surface thinning and elevation changes (dh/dt) (Rivera et al., 2007; Willis et al., 2012 warming has caused a decreased in the amount of precipitation falling as snow and increased 100 ablation, exacerbating glacier recession (Rasmussen et al., 2007). 102Some of these changes in precipitation have been related to variations in the strength of the 103 prevailing Southern Hemisphere Westerlies, with stronger westerlies augmenting local precipitation. 104Stronger westerlies will also result in a decreased amplitude of the local air temperature annual cycle, 105Manuscript published in Global and Planetary Change, 2016 4 while weaker westerlies result in a colder winter and warmer summer, increasing temperature 106 seasonality (Garreaud et al., 2013). The core of the Southern Hemisphere Westerlies is currently 50 107 to 55°S, but through the Holocene latitudinal variations in these winds periodically brought increased 108 precipitation to the area, driving glacier advance and recession (Boex et al., 2013;Lamy et al., 2010; 109 Moreno et al., 2012) but with a pronounced east-west shift (Ackert et al., 2008). The drainage basins were edited to include nunataks and this new dataset we refer to herein as 176'glacier outlines'. Nunataks, or areas of ice-free terrain, were identified in this study using Landsat 8 177Operational Land Imager (OLI) scenes and a mask derived from the Normalised Difference Snow 178Index (NDSI = (Green -SWIR)/(Green + SWIR)). OLI scenes w...

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

“…For a similar reconstruction approach, combining mass conservation with the SIA along glacier flow lines, Farinotti et al (2009b) apply a 5 • limit. Assuming perfect plasticity to infer glacier thickness in Patagonia, Carrivick et al (2016) set a lower limit of 1.7 • . Even though our choice for α 0 is somewhat lower, the limit is still applied over a 17 % area fraction of the Vestfonna ice cap (VIC) test geometry (Sect.…”

“…In the Ice Thickness Models Intercomparison eXperiment , two types of reconstruction approaches rely exclusively on this geometric information. The first type assumes perfect plasticity, relating ice thickness to a glacier-specific yield stress, which itself is inferred from the elevation range of the glacier (Linsbauer et al, 2012;Frey et al, 2014;Carrivick et al, 2016). The second type assumes that characteristics of the ice-covered bed topography resemble the nearby ice-free landscape (Clarke et al, 2009).…”

The Last Glacial Maximum and deglaciation in central Patagonia, 44°S–49°S

“…In addition to these icefields, two smaller icefields, the Cordillera Darwin and Gran Campo Nevado, along with numerous smaller glaciers are all that remain of the former PIS. The present day NPI covers an area of 3976 km 2 (Davies and Glasser, 2012), contains 1234.6 km 3 of ice (3.10 mm sea-level equivalent) (Carrivick et al, 2016) and has a mean ice thickness of 305 m. The equilibrium line altitude ranges from ~900 m in the west to ~1300 m in the east (Rivera et al, 2007).…”

Rapid Surface Lowering of Benito Glacier, Northern Patagonian Icefield

“…With a combined area and ice volume of 17,467 and 5,562 km 3 , respectively, the Northern and Southern Patagonian Icefields (NPI and SPI) are the largest temperate ice masses in the Southern Hemisphere, outside of Antarctica (Warren and Sugden, 1993;Carrivick et al, 2016). Since the end of the Little Ice Age (∼1870), the outlet glaciers of the two icefields have generally thinned and retreated in response to negative surface mass balance and ice flow acceleration (Rosenblüth et al, 1997;Rignot et al, 2003;Harrison et al, 2007;Rasmussen et al, 2007;Masiokas et al, 2009;Glasser et al, 2011;Davies and Glasser, 2012).…”

“…The NPI (or Hielo Patagonico Norte) is the smaller of the two icefields, with a present day area of 4,152 km² and ice volume of 1,235 km 3 (Carrivick et al, 2016), and has accounted for 27% of the total mass loss from both the icefields since 1975 (Rignot et al, 2003;Rivera et al, 2007). The NPI is drained by 70 land-or lake-terminating glaciers, except for San Rafael which calves into a tidal lagoon Willis et al, 2012;Carrivick et al, 2016).…”