The climate memory of an Arctic polythermal glacier

Delcourt, Charlotte; Liefferinge, Brice Van; Nolan, M.; Pattyn, Frank

doi:10.3189/2013joj12j109

Cited by 3 publications

(4 citation statements)

References 38 publications

(9 reference statements)

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“…The inferred rapidity of channel adjustment indicates that drainage pathways in cold ice can and do evolve, in contrast to their characterization as static, ‘relict’ features (Hodgkins, 1997), and may incise to a subglacial location (Bælum & Benn, 2011; Gulley, Benn, Müller, & Luckman, 2009a; Gulley, Benn, Screaton, & Martin, 2009b; Naegeli et al, 2014; Temminghoff et al, 2019). Under forecasts for warmer and longer Arctic melt seasons (Post et al, 2019), and projections of glacier thinning to result in more extensive areas of cold ice across the region (Delcourt et al, 2013; Irvine‐Fynn et al, 2011; Østby et al, 2017; Wilson & Flowers, 2013), increasing meltwater fluxes may accelerate cut‐and‐closure channel formation (Gulley, Benn, Müller, & Luckman, 2009a) and the subsequent englacial drainage evolution (e.g. Vatne & Irvine‐Fynn, 2016), which may ultimately lead to incision to the glacier bed.…”

Section: Discussionmentioning

confidence: 99%

“…A considerable proportion of the valley glaciers in this climate‐sensitive region exhibit cold or polythermal temperature regimes (Aschwanden & Blatter, 2009; Blatter & Hutter, 1991; Hagen et al, 1993; Irvine‐Fynn et al, 2011; Miller, 1976). Under regional projections of continued atmospheric warming and glacier thinning, ice masses with a cold‐ice thermal regime are predicted to become more commonplace (Delcourt et al, 2013; Irvine‐Fynn et al, 2011; Østby et al, 2017; Wilson & Flowers, 2013). The presence and distribution of cold ice within a glacier can define its hydrological functioning (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Morphology, flow dynamics and evolution of englacial conduits in cold ice

Kamintzis

Irvine‐Fynn

Holt

et al. 2022

Earth Surf Processes Landf

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Meltwater routing through ice masses exerts a fundamental control over glacier dynamics and mass balance, and proglacial hydrology. However, despite recent advances in mapping drainage systems in cold, Arctic glaciers, direct observations of englacial channels and their flow conditions remain sparse. Here, using Terrestrial Laser Scanning (TLS) surveys of the main englacial channel of cold-based Austre Brøggerbreen (Svalbard), we map and compare an entrance moulin reach (122 m long) and exit portal reach (273 m long). Analysis of channel planforms, longitudinal profiles, cross-sections and morphological features reveals evidence of spatial variations in water flow conditions and channel incision mechanisms, and the presence of vadose, epiphreatic and phreatic conditions. The entrance reach, located at the base of a perennial moulin, was characterised by vadose, uniform, channel lowering at annual timescales, evidenced by longitudinal grooves, whereas the exit portal reach showed both epiphreatic and vadose conditions, along with upstream knickpoint migration at intra-annual timescales. Fine-scale features, including grooves and scallops, were readily quantified from the TLS point cloud, highlighting the capacity of the technique to inform palaeoflow conditions, and reveal how pulses of meltwater from rainfall events may adjust englacial conduit behaviour. With forecasts of increasing Arctic precipitation in the coming decades, and a progressively greater proportion of glaciers comprising cold ice, augmenting the current knowledge of englacial channel morphology is essential to constrain future glacier hydrological system change.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Morphology, flow dynamics and evolution of englacial conduits in cold ice

Kamintzis

Irvine‐Fynn

Holt

et al. 2022

Earth Surf Processes Landf

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“…In many glacierized regions, atmospheric warming, rising snowlines, and expanding ablation areas may result in extensive supraglacial hydrology even as total glacier areas decline. Similarly, glacier thinning and cooling in higher latitudes (e.g., Delcourt, Liefferinge, Nola, & Pattyn, ; Irvine‐Fynn, Hodson, et al, ) may also promote an increasing dominance of supraglacial hydrology. Consequently, understanding the influence that the weathering crust has on modulating supraglacial run‐off and its characteristics is important to improve predictive hydrological models.…”

Section: Discussionmentioning

confidence: 99%

Near‐surface hydraulic conductivity of northern hemisphere glaciers

Stevens

Irvine‐Fynn

Porter

et al. 2018

Hydrological Processes

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The hydrology of near‐surface glacier ice remains a neglected aspect of glacier hydrology despite its role in modulating meltwater delivery to downstream environments. To elucidate the hydrological characteristics of this near‐surface glacial weathering crust, we describe the design and operation of a capacitance‐based piezometer that enables rapid, economical deployment across multiple sites and provides an accurate, high‐resolution record of near‐surface water‐level fluctuations. Piezometers were employed at 10 northern hemisphere glaciers, and through the application of standard bail–recharge techniques, we derive hydraulic conductivity (K) values from 0.003 to 3.519 m day−1, with a mean of 0.185 ± 0.019 m day−1. These results are comparable to those obtained in other discrete studies of glacier near‐surface ice, and for firn, and indicate that the weathering crust represents a hydrologically inefficient aquifer. Hydraulic conductivity correlated positively with water table height but negatively with altitude and cumulative short‐wave radiation since the last synoptic period of either negative air temperatures or turbulent energy flux dominance. The large range of K observed suggests complex interactions between meteorological influences and differences arising from variability in ice structure and crystallography. Our data demonstrate a greater complexity of near‐surface ice hydrology than hitherto appreciated and support the notion that the weathering crust can regulate the supraglacial discharge response to melt production. The conductivities reported here, coupled with typical supraglacial channel spacing, suggest that meltwater can be retained within the weathering crust for at least several days. Not only does this have implications for the accuracy of predictive meltwater run‐off models, but we also argue for biogeochemical processes and transfers that are strongly conditioned by water residence time and the efficacy of the cascade of sediments, impurities, microbes, and nutrients to downstream ecosystems. Because continued atmospheric warming will incur rising snowline elevations and glacier thinning, the supraglacial hydrological system may assume greater importance in many mountainous regions, and consequently, detailing weathering crust hydraulics represents a research priority because the flow path it represents remains poorly constrained.

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“…Mass loss, however, began to stabilize as the terminus retreated towards a prominent riegel (Holmlund & Holmlund 2019), combined with cooling of the front part of the glacier due to thinning, decreasing its velocity (Delcourt et al . 2013).…”

Section: Debris Ridges On Storglaciärenmentioning

confidence: 99%

Thrust faulting in glaciers? Re‐examination of debris bands near the margin of Storglaciären, Sweden

Monz

Hudleston

Cook

et al. 2021

Boreas

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Thrust faulting has been suggested as a viable mechanism of debris transport at many glaciers, often inferred from the presence of up‐glacier dipping bands of debris that emerge at the ice surface to form ridges of basally derived material. However, modelling indicates that the development of thrust faults is mechanically inhibited because stresses are much lower than that required for shear failure, a prerequisite for thrust faulting, and field measurements fail to detect thrust‐related displacement. The mechanism for the emplacement of these ridges that appear at the surface of many polythermal valley glacier termini remains open to question. This study re‐examines the origin of debris ridges on the surface of Storglaciären, a polythermal valley glacier in northern Sweden, using field observations, ice microstructural analyses, sediment grain size analysis, stable isotope composition of the ice, and modelling. We find no evidence of discrete displacement across the debris bands that produce the ridges, nor do we find evidence that folding might be responsible. We propose that the bands originate at the base of the glacier by one of two mechanisms, perhaps in combination: (i) refreezing of meltwater near the thermal transition in basal ice, and (ii) injection into tensile fractures periodically opened at the base due to high fluid pressure and then freezing. In either case, separation from the base occurs due to high fluid pressure and freezing introduces ice below the debris bands, which are then transported forwards due to basal shear and upwards due to longitudinal compression, and revealed by surface ablation.

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The climate memory of an Arctic polythermal glacier

Cited by 3 publications

References 38 publications

Morphology, flow dynamics and evolution of englacial conduits in cold ice

Morphology, flow dynamics and evolution of englacial conduits in cold ice

Near‐surface hydraulic conductivity of northern hemisphere glaciers

Thrust faulting in glaciers? Re‐examination of debris bands near the margin of Storglaciären, Sweden

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