Evolution of high-Arctic glacial landforms during deglaciation

Abstract

Glacial landsystems in the high-Arctic have been reported to undergo geomorphological transformation during deglaciation. This research evaluates moraine evolution over a decadal timescale at Midtre Lovénbreen, Svalbard. This work is of interest because glacial landforms developed in Svalbard have been used as an analogue for landforms developed during Pleistocene mid-latitude glaciation. Ground penetrating radar was used to investigate the subsurface characteristics of moraines. To determine surface change, a LiDAR topographic data set (obtained 2003) and a UAV-derived (obtained 2014) digital surface model processed using structure-from-motion (SfM) are also compared. Evaluation of these data sets together enables subsurface character and landform response to climatic amelioration to be linked. Ground penetrating radar evidence shows that the moraine substrate at Midtre Lovénbreen includes ice-rich (radar velocities of 0.17 m ns (mean thresholded rate of −4.39 m over the 11-year observation period). However, the debris-rich zones show a relatively low rate of surface change (mean thresholded rate of −0.98 m over the 11-year observation period), and the morphology of the debris-rich landforms appear stable over the observation period. A complex response of proglacial landforms to climatic warming is shown to occur within and between glacier forelands as indicated by spatially variable surface lowering rates. Landform response is controlled by the ice-debris balance of the moraine substrate, along with the topographic context (such as the influence of meltwater). Site-specific characteristics such as surface debris thickness and glaciofluvial drainage are, therefore, argued to be a highly important control on surface evolution in ice-cored terrain, resulting in a diverse response of high-Arctic glacial landsystems to climatic amelioration. These results highlight that care is needed when assessing the long-term preservation potential of contemporary landforms at high-Arctic glaciers. A better understanding of ice-cored terrain facilitates the development of appropriate age and climatic interpretations that can be obtained from palaeo ice-marginal landsystems.

Quantification of historical landscape change on the foreland of a receding polythermal glacier, Hørbyebreen, Svalbard

“…In terms of elevation changes, the average lowering of ice-cored lateral moraines in the period 1960-2009 varied from 0 to 1.5 m/year depending on the local situation. Such values are in the same order of magnitude as those of other Svalbard glaciers (Ewertowski, 2014;Ewertowski and Tomczyk, 2015;Irvine-Fynn et al, 2011;Midgley et al, 2018;Schomacker and Kjaer, 2008;Tonkin et al, 2016). The remaining part of the proglacial area (approximately 10% in 2013) was stable over this period and in equilibrium with current climatic and environmental conditions.…”

“…Moreover, quantification of the dynamics of landform evolution on glacier forelands using time-series of digital elevation models or airborne laser scanning has to date been limited (e.g. Bernard et al, 2016;Etzelmüller, 2000a;Etzelmüller, 2000b;Irvine-Fynn et al, 2011;Kociuba, 2016;Midgley et al, 2018;Tonkin et al, 2016).…”

Glacial geomorphological mapping: A review of approaches and frameworks for best practice

“…Geophysical surveying methods can also strengthen links between modern and ancient landform records through surveying of the internal architecture of landforms that can be directly linked to depositional processes, as well as glaciological and climatic conditions (e.g. Bennett et al, 2004;Benediktsson et al, 2009Benediktsson et al, , 2010Lukas and Sass, 2011;Midgley et al, 2013Midgley et al, , 2018. Recent advances in geophysical imaging of sub-ice geomorphology has allowed links to be made between modern and palaeo-ice sheets (see Section 3.2.2.3), and we expect this to a growth area going forward (see also Stokes, 2018).…”

New fjords, new coasts, new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund, southern Svalbard)

“…The rapid exposure of land from Svalbard glaciers (over 20% of glacierized terrain decrease) activates sediment cascades through which exposed glacigenic sediments are transported and can then be stored in the form of solifluction slope covers, fluvial floodplains, lakes and within the coastal zone in the form of beaches, tidal flats or as marine sediments in the bottoms of fjords (e.g. Lønne & Lyså, 2005;Midgley et al, 2018;Ewertowski et al, 2019;Weckwerth et al, 2019).…”