Active temperate glacial landsystem evolution in association with outwash head/depositional overdeepenings

Abstract

The response of temperate glaciers to rapid climate warming is reflected in the geomorphology (landsystem) resulting from snout recession. This paper develops a locally diverse process-form model of active temperate glaciers through mapping and quantification of historical landscape change on the Fjallsjökull-Hrútárjökull foreland, SE Iceland. Quantification of volumetric and areal changes on the foreland are based on time series of archival aerial images for the period 1945-1998, high-resolution satellite imagery for 2014 and digital elevation models of differences derived from time series of UAV imagery for the years 2014, 2016, 2018, 2019 and 2022. Landscape change and glacier snout behaviour since 1945 highlights the importance of azonal and potentially intrazonal signatures in temperate glacial landsystems, particu- larly: (1) the development and collapse of partially supraglacial outwash fans to produce outwash heads fronting depositional overdeepenings; and (2) the emergence of ice-cored eskers that record the evolution of englacial drainage networks operating over overdeepenings. Such landform assemblages are manifested as substantial icecored/hummocky terrains, a characteristic of deglaciating forelands that is likely to be widely replicated wherever ice-contact glacifluvial assemblages create outwash heads that act as depositional overdeepenings. Due to its significantly greater supraglacial debris cover, complete de-icing of the Hrútárjökull snout in response to post-1945 warming was delayed until around 2014. This constitutes a prime example of incremental stagnation, which in a rapidly warming climate has resulted in significant landscape change (land surface elevation collapse of 0.8 m a À1 ) over the last 8 years.

The evolution and preservation potential of englacial eskers: An example from Breiðamerkurjökull, SE Iceland

“…This work highlights the value of UAVs for geomorphological mapping and process-form studies, which has become a popular approach in recent years (Chandler et al, 2016(Chandler et al, , 2020Ely et al, 2017;Evans et al, 2016Evans et al, , 2023Hackney & Clayton, 2015;Tomczyk et al, 2019). UAV surveys have filled the spatial resolution mismatch between field geomorphology and aerial/satellite remote sensing data ( Śledź et al, 2021).…”

“…Eskers, which record the location of channelised drainage, are sinuous ridges of glaciofluvial sediment deposited in an ice‐walled channel (Brennand, 2000; Huddart et al, 1999; Price, 1969). Eskers are abundant across the beds of palaeo‐ice sheets and have been identified in contemporary glacierised environments (Bennett & Evans, 2012; Burke et al, 2008; Evans et al, 2023; Evans & Twigg, 2002; Howarth, 1971; Huddart et al, 1999; Knudsen, 1995; Price, 1969; Storrar et al, 2015). Eskers deposited englacially have also been observed in ancient and modern glacial settings (Bennett & Evans, 2012; Burke et al, 2008; Evans et al, 2023; Howarth, 1971; Perkins et al, 2016; Price, 1969).…”

Quantification of short‐term transformations of proglacial landforms in a temperate, debris‐charged glacial landsystem, Kvíárjökull, Iceland

“…The average net ) was recorded . Other land elements in the foreland of Fjallsjökull and Hrútárjökull (Iceland) were characterized by average annual elevation changes between À0.08 and À1.33 m a À1 (Table 4) (Evans et al, 2023). : 1945-1964, 1964-1980, 1980-1998 and 1998-2003.…”

“…In inhabited parts of mountain and polar regions, the dynamics and scale of landform transformations on glacial forelands may have serious implications for infrastructure and human populations located in the same catchment (Cook et al, 2016(Cook et al, , 2018Harrison et al, 2018). Therefore, there is a strong justification for the monitoring of proglacial areas in such settings in order to understand the temporal aspects of landscape change during deglaciation, especially the de-icing of buried glacier ice masses (Bennett & Evans, 2012;Blauvelt et al, 2020;Evans et al, 2023;Ewertowski & Tomczyk, 2015;Kjaer & Krüger, 2001;Krüger & Kjaer, 2000;Schomacker, 2008;Schomacker & Kjaer, 2007, 2008, as they pertain to applied glacial and paraglacial geomorphology (Carrivick & Heckmann, 2017). Not unrelated to this is the need to better quantify glacial process-form regimes as they pertain to spatio-temporal change in modern glacial landsystems (e.g., Bennett et al, 2010;Bennett & Evans, 2012;Evans et al, 2009Evans et al, , 2019Evans et al, , 2022Evans & Twigg, 2002;Ewertowski et al, 2019;Eyles, 1983aEyles, , 1983bMidgley et al, 2018;Price, 1980).…”

“…In cold climate settings, the impact has been manifested as dynamic responses in glacial systems (Benn et al, 2012; Benn & Evans, 2010). The recent fluctuations in volume and extent of glaciers have been widely analysed (e.g., Bash et al, 2018; Bash & Moorman, 2020; Carrivick et al, 2019; Hugonnet et al, 2021; Jouvet et al, 2019; Kienholz et al, 2020; Małecki, 2016; Małecki, 2022; Rossini et al, 2018; Sziło & Bialik, 2018) but less attention has been paid to geomorphological transformations taking place in proglacial areas and their possible links to climate warming (Bennett et al, 2010; Bennett & Evans, 2012; Carrivick & Heckmann, 2017; Chandler, Chandler, et al, 2020; Evans et al, 2023; Ewertowski et al, 2019; Ewertowski & Tomczyk, 2020; Hedding et al, 2020; Schomacker, 2008; Seier et al, 2017; Staines et al, 2015; Strzelecki et al, 2018).…”