Abstract
Ongoing changes in mountain glaciers affect local water resources, hazard potential and global sea level. An increasing proportion of remaining mountain glaciers are affected by the presence of a surface cover of rock debris, and the response of these debris-covered glaciers to climate forcing is different to that of glaciers without a debris cover. Here we take a back-to-basics look at the fundamental terms that control the processes of debris evolution at the glacier surface, to illustrate how the trajectory of debris cover development is partially decoupled from prevailing climate conditions, and that the development of a debris cover over time should prevent the glacier from achieving steady state. We discuss the approaches and limitations of how this has been treated in existing modeling efforts and propose that “surrogate world” numerical representations of debris-covered glaciers would facilitate the development of well-validated parameterizations of surface debris cover that can be used in regional and global glacier models. Finally, we highlight some key research targets that would need to be addressed in order to enable a full representation of debris-covered glacier system response to climate forcing.
Highlights
Glaciers respond sensitively to climate variability with attendant impacts on melt water production, sea-level rise and geomorphic hazards (e.g. Watanabe et al, 1994; Kääb et al, 2005; Kaser et al, 2010; Bolch et al, 2011; Huss, 2011; Leclercq et al, 2011; Immerzeel et al, 2012; Marzeion et al, 2012)
In this paper we review the fundamentals of how supraglacial debris cover influences the climate response of mountain glaciers and identify some priorities for furthering our understanding of these systems
The simple illustrations of the fundamental properties of debriscovered glaciers presented in the previous sections, show that 1) the impact of supraglacial debris cover on the glacier mass balance is controlled by linked processes that are time-dependent, and themselves related to the temporal changes in supraglacial debris extent and thickness, 2) these time-dependent processes and the related thresholds and feedbacks between them together determine the climate response of debris-covered glaciers and 3) the conditions of steady state are unlikely to be achievable for a debris-covered glacier, even with idealized constant climate forcing
Summary
Glaciers respond sensitively to climate variability with attendant impacts on melt water production, sea-level rise and geomorphic hazards (e.g. Watanabe et al, 1994; Kääb et al, 2005; Kaser et al, 2010; Bolch et al, 2011; Huss, 2011; Leclercq et al, 2011; Immerzeel et al, 2012; Marzeion et al, 2012). Stokes et al, 2007; Hagg et al, 2008; Scherler et al, 2011a; Kääb et al, 2012), and globally the proportion of debris-covered ice is expected to increase as mountain glacier volumes diminish in coming decades (Stokes et al, 2007; Bolch et al, 2008a; Shukla et al, 2009; Lambrecht et al, 2011; Herreid and Pellicciotti, 2020; Tielidze et al, 2020). Berthier et al, 2007; Bolch et al, 2008b, 2011) Together, these two points imply that understanding the role of surface debris on meltwater production will be prerequisite to correctly forcasting the volume and timing of glacier meltwater contributions to local hydrological resources and global sea level rise in the coming decades and centuries. We conclude with summary comments on the nature of the problem and the potential ways forward
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
