Factors influencing the basal temperatures of a High Arctic polythermal glacier

Wohlleben, Trudy; Sharp, Martin; Bush, Andrew B. G.

doi:10.3189/172756409789624210

Cited by 21 publications

(31 citation statements)

References 29 publications

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“…6a), and the modelled contribution of basal sliding is therefore very limited. Our value of 150 mW m −2 differs significantly from the the 350 mW m −2 found by Wohlleben et al (2009), which is ex- pected given the very different setting (location, SMB, meltwater production and infiltration mechanisms) and the different methodological approach. Here we tune based on an evolving/modelled geometry, while Wohlleben et al (2009) model the thermodynamics for a fixed geometry.…”

Section: Englacial Ice Temperaturescontrasting

confidence: 53%

“…Our value of 150 mW m −2 differs significantly from the the 350 mW m −2 found by Wohlleben et al (2009), which is ex- pected given the very different setting (location, SMB, meltwater production and infiltration mechanisms) and the different methodological approach. Here we tune based on an evolving/modelled geometry, while Wohlleben et al (2009) model the thermodynamics for a fixed geometry. With a value of 350 mW m −2 almost the entire ablation area of the ice cap would be at the pressure melting point, and basal sliding would have an important role, which is not supported by the field evidence.…”

Section: Englacial Ice Temperaturescontrasting

confidence: 53%

“…We incorporate this additional heat source by imposing a basal-water heat flux (similar to geothermal heating), following the approach of Wohlleben et al (2009). This mechanism differs from cryo-hydrologic warming (Phillips et al, 2010), where meltwater heating also plays a crucial role (through flowing, ponding and refreezing) but where the heat source is spread and leads to a warming of the whole ice column.…”

Section: Thermodynamics and Role Of Meltwatermentioning

confidence: 99%

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Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

et al. 2017

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Abstract. In this study the dynamics and sensitivity of Hans Tausen Iskappe (western Peary Land, Greenland) to climatic forcing is investigated with a coupled ice flow–mass balance model. The surface mass balance (SMB) is calculated from a precipitation field obtained from the Regional Atmospheric Climate Model (RACMO2.3), while runoff is calculated from a positive-degree-day runoff–retention model. For the ice flow a 3-D higher-order thermomechanical model is used, which is run at a 250 m resolution. A higher-order solution is needed to accurately represent the ice flow in the outlet glaciers. Under 1961–1990 climatic conditions a steady-state ice cap is obtained that is overall similar in geometry to the present-day ice cap. Ice thickness, temperature and flow velocity in the interior agree well with observations. For the outlet glaciers a reasonable agreement with temperature and ice thickness measurements can be obtained with an additional heat source related to infiltrating meltwater. The simulations indicate that the SMB–elevation feedback has a major effect on the ice cap response time and stability. This causes the southern part of the ice cap to be extremely sensitive to a change in climatic conditions and leads to thresholds in the ice cap evolution. Under constant 2005–2014 climatic conditions the entire southern part of the ice cap cannot be sustained, and the ice cap loses about 80 % of its present-day volume. The projected loss of surrounding permanent sea ice and resultant precipitation increase may attenuate the future mass loss but will be insufficient to preserve the present-day ice cap for most scenarios. In a warmer and wetter climate the ice margin will retreat, while the interior is projected to thicken, leading to a steeper ice cap, in line with the present-day observed trends. For intermediate- (+4 °C) and high- warming scenarios (+8 °C) the ice cap is projected to disappear around AD 2400 and 2200 respectively, almost independent of the projected precipitation regime and the simulated present-day geometry.

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Section: Englacial Ice Temperaturescontrasting

confidence: 53%

Section: Englacial Ice Temperaturescontrasting

confidence: 53%

Section: Thermodynamics and Role Of Meltwatermentioning

confidence: 99%

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Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

et al. 2017

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“…Robin, 1955;Dahl-Jensen, 1989;Greve, 1997b;Breuer et al, 2006;Aschwanden et al, 2012). Thermal structure is relevant to glacier hydrology (Wohlleben et al, 2009;IrvineFynn et al, 2011), rheology (Duval, 1977) and mass balance (e.g. Delcourt et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…The impacts of previous glacier states on the thermal structures of Arctic glaciers have been explored using numerical methods by Delcourt et al (2008) and Wohlleben et al (2009). In some cases (e.g.…”

Section: Introductionmentioning

confidence: 99%

Environmental controls on the thermal structure of alpine glaciers

Wilson

Flowers

2013

The Cryosphere

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Abstract. Water entrapped in glacier accumulation zones represents a significant latent heat contribution to the development of thermal structure. It also provides a direct link between glacier environments and thermal regimes. We apply a two-dimensional mechanically-coupled model of heat flow to synthetic glacier geometries in order to explore the environmental controls on flowband thermal structure. We use this model to test the sensitivity of thermal structure to physical and environmental variables and to explore glacier thermal response to environmental changes. In different conditions consistent with a warming climate, mean glacier temperature and the volume of temperate ice may either increase or decrease, depending on the competing effects of elevated meltwater production, reduced accumulation zone extent and thinning firn. For two model reference states that exhibit commonly-observed thermal structures, the fraction of temperate ice is shown to decline with warming air temperatures. Mass balance and aquifer sensitivities play an important role in determining how the englacial thermal regimes of alpine glaciers will adjust in the future.

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Cooling glaciers in a warming climate since the Little Ice Age at Qaanaaq, northwest Kalaallit Nunaat (Greenland)

Carrivick

Smith

Sutherland

et al. 2023

Earth Surf Processes Landf

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The centennial response of land‐terminating glaciers in Greenland to climate change is largely unknown. Yet, such information is important to understand ongoing changes and for projecting the future evolution of Arctic subpolar glaciers, meltwater runoff, and sediment fluxes. This paper analyses the topography, geomorphology, and sedimentology of prominent moraine ridges and the proglacial areas of ice cap outlet glaciers on the Qaanaaq peninsula (Piulip Nunaa). We determine geometric changes of glaciers since the neoglacial maximum; the Little Ice Age (LIA), and we compare glacier behaviour during the LIA with that of the present day. There has been very little change in the rate of volume loss of each outlet glacier since the LIA compared with the rate between 2000 and 2019. However, the percentage of each glacier that is likely composed of cold‐based ice has increased since the LIA, typically by 20%. The LIA moraines comprise subrounded, striated, and faceted clasts that evidence subglacial transport, and outwash plains, flutes, kames, and eskers that evidence subglacial motion and meltwater within temperate ice. Contrastingly, contemporary ice margins and their convex ice surfaces comprise pronounced primary foliation, ephemeral supraglacial drainage, sediment drapes from thrust plane fractures, and an absence of open crevasses and moulins. These calculations and observations together lead us to interpret that these outlet glaciers have transitioned towards an increasingly cold‐based thermal regime despite a warming regional climate. Thermal regime transitions control glacier dynamics and therefore should be incorporated into glacier evolution models, especially where polythermal glaciers prevail and where climate is changing rapidly.

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Factors influencing the basal temperatures of a High Arctic polythermal glacier

Cited by 21 publications

References 29 publications

Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)

Environmental controls on the thermal structure of alpine glaciers

Cooling glaciers in a warming climate since the Little Ice Age at Qaanaaq, northwest Kalaallit Nunaat (Greenland)

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