Abstract
Abstract. Glaciers and rock glaciers play an important role in the hydrology of the semi-arid northern Chile. Several studies show that glaciers have rapidly lost mass in response to climate change during the last decades. The response of rock glaciers to climate change in this region is, however, less known. In this study we use a combination of historical aerial photography, stereo satellite imagery, airborne lidar, and the Shuttle Radar Topography Mission (SRTM) DEM to report glacier changes for the Tapado Glacier–rock glacier complex from the 1950s to 2020 and to report mass balances for the glacier component of the complex, Tapado Glacier. Furthermore, we examine high-resolution elevation changes and surface velocities between 2012 and 2020 for 35 rock glaciers in the La Laguna catchment. Our results show how Tapado Glacier has shrunk by -25.2±4.6 % between 1956 and 2020, while the mass balance of Tapado Glacier has become steadily more negative, from being approximately in balance between 1956 and 1978 (-0.04±0.08 m w.e. a−1) to showing increased losses between 2015 and 2020 (-0.32±0.08 m w.e. a−1). Climatological (re-)analyses reveal a general increase in air temperature, decrease in humidity, and variable precipitation since the 1980s in the region. In particular, the severe droughts starting in 2010 resulted in a negative mass balance of -0.54±0.10 m w.e. a−1 between 2012 and 2015. The rock glaciers within the La Laguna catchment show heterogenous changes, with some sections of landforms exhibiting pronounced elevation changes and surface velocities exceeding that of Tapado Glacier. This could be indicative of high ice contents within the landforms and also highlights the importance of considering how landforms can transition from more glacial landforms to more periglacial features under permafrost conditions. As such, we believe high-resolution (sub-metre) elevation changes and surface velocities are a useful first step for identifying ice-rich landforms.
Highlights
The cryosphere is in a state of rapid change, with glaciers thinning and losing mass on a global scale (Zemp et al, 2019)
Our results show that since the 1950s, Tapado Glacier has had a geodetic mass balance approximately in line with the glaciers within the Maipo basin of central Chile (∼ 400 km to the south), which had a regional average −0.12 ± 0.06 m w.e. a−1 with individual glacier mass balances ranging from −0.28 ± 0.07 to 0.18 ± 0.07 m w.e. a−1 (Farías-Barahona et al, 2020a), but is less negative than El Morado Glacier, within the Maipo basin (−0.39 ± 0.15 m w.e. a−1 between 1955 and 2015), this glacier is situated at a lower elevation than Tapado Glacier and has a calving front (Fariás-Barahona et al, 2020b)
We found that certain rock glaciers had sections that were flowing at rates in excess of 4 m a−1, which is considerably faster than the catchment average of 0.54±0.03 m a−1, as well as the surface velocities observed on the Tapado complex and Las Tetas rock glacier which are at least partly glacial in origin
Summary
The cryosphere is in a state of rapid change, with glaciers thinning and losing mass on a global scale (Zemp et al, 2019). The Andes have some of the highest rates of glacier mass loss on the planet (Masiokas et al, 2020), with a total loss of −0.72 ± 0.22 m w.e. yr−1 between 2000 and 2018 (Dussaillant et al, 2019; Ferri et al, 2020). Retreating glaciers are predicted to alter the hydrological cycle, in regions where cryospheric contributions to streamflow are significant. Robson et al.: Glacier and rock glacier changes since the 1950s in the La Laguna catchment flow where glacial contribution is > 25 % (Buytaert et al, 2017)
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