Network connection interrupted icefaces drivers#

Therefore, ice cliff formation has been suggested to be triggered by several possible mechanisms, including the collapse of englacial conduits (Benn et al., 2012 Immerzeel et al., 2014 Reid & Brock, 2014 Sakai & Takeuchi, 2000 Watson, Quincey, Carrivick & Smith, 2017 Watson, Quincey, Smith, et al., 2017 Westoby et al., 2020) slope oversteepening, for example from differential melt under the debris (Sakai et al., 1998 Sharp, 1949 Westoby et al., 2020) crevasse opening (Reid & Brock, 2014) undercutting by supraglacial ponds or streams (Moore, 2018 Nicholson et al., 2018) and melt enhancement at pond margins (Miles, Steiner, et al., 2017 Miles, Willis, et al., 2017 Röhl, 2006, 2008 Sakai & Takeuchi, 2000) that may sometimes lead to accelerated steepening from calving (Benn et al., 2012 Immerzeel et al., 2014 Röhl, 2006, 2008).Ĭontrary to the surrounding debris‐covered ice, ice cliffs are directly exposed to incoming radiation and therefore act as melt “hotspots” (Buri, Miles, et al., 2016 Juen et al., 2014 Sakai et al., 1998). Cliffs appear when the surface slope is too steep for the debris to remain on it (Moore, 2018). They consist of steep, bare, or very thinly debris‐covered ice faces within the debris‐covered part of the glacier and are often associated with supraglacial streams or ponds (Mölg et al., 2019 Steiner et al., 2019).

Ice cliffs have been observed in all the main mountain ranges of the planet (Anderson et al., 2021 Benn et al., 2001 Chinn & Dillon, 1987 Herreid & Pellicciotti, 2018 Inoue & Yoshida, 1980 Johnson, 1992 Mölg et al., 2019 Moore, 2018 Ogilvie, 1904 Reid & Brock, 2014 Röhl, 2006 Sakai et al., 1998 Shahgedanova et al., 2005) and have been observed to account for 1%–12% of the total debris‐covered area (Anderson et al., 2021 Brun et al., 2018 Kneib et al., 2020 Reid & Brock, 2014 Sakai et al., 1998). These glaciers are often characterized by undulating, hummocky topography (Bartlett et al., 2020) and their surface is punctuated by supraglacial ponds, streams, and ice cliffs.

These results have implications for the melt of debris‐covered glaciers, in addition to showing the high rate of changes at their surface and highlighting some of the links between cliff population and glacier state.ĭebris‐covered glaciers are widespread in all mountain ranges around the globe (Herreid & Pellicciotti, 2020b Scherler et al., 2018) and especially in High Mountain Asia (HMA), where half of the glaciers larger than 2 km 2 have more than 5% of their total area covered by a layer of rock debris (Herreid & Pellicciotti, 2020b) varying in thickness from centimeter to meter scale.

Network connection interrupted icefaces drivers#

In some extreme cases (here, a glacier surge), these external drivers may lead to a reorganization of the cliffs at the glacier surface and a change in the natural variability. In a subsequent step, the inclusion of external drivers related to climate, glacier dynamics, and hydrology highlights the influence of these variables on the cliff population dynamics, which is usually not a direct one due to the complexity and interdependence of the processes taking place at the glacier surface. Our results show that while the cliff relative area can change by up to 20% from year to year, the natural long‐term variability is constrained, thus defining a glacier‐specific cliff carrying capacity. We then quantified the processes occurring at the feature scale to train a stochastic birth‐death model to represent the cliff population dynamics. Here, we systematically mapped and tracked ice cliffs across four debris‐covered glaciers in High Mountain Asia for every late ablation season from 2009 to 2019 using high‐resolution multi‐spectral satellite imagery. Previous studies have shown that their number and relative area can change considerably from year to year, but this variability has not been explored, in part because available cliff observations are irregular. Ice cliffs are common on debris‐covered glaciers and have relatively high melt rates due to their direct exposure to incoming radiation.