scholarly journals The Seasonal Evolution of Subglacial Drainage Pathways Beneath a Soft-bedded Glacier

2021 ◽  
Author(s):  
Jane Hart ◽  
David Young ◽  
Nathaniel Baurley ◽  
Benjamin Robson ◽  
Kirk Martinez
Keyword(s):  
Climate Change ◽  
Sediment Layer ◽  
West Antarctica ◽  
Ice Streams ◽  
Seasonal Evolution ◽  
Rapid Access ◽  
Speed Up ◽  
Self Organizing ◽  
Subglacial Drainage

Abstract Subglacial hydrology is a key element in glacier response to climate change, but investigations of this environment are logistically difficult. Most models are based on summer data from glaciers resting on rigid bedrocks. However a significant number of glaciers rest on soft (unconsolidated sedimentary) beds, including the potentially unstable ice streams of West Antarctica. Here we present a rare multi-year instrumented record of the development of seasonal subglacial behavior in a temperate glacier resting on a deformable sediment layer as an analogue for West Antarctica. We observe a distinct annual pattern in the subglacial hydrology based on self-organizing anastomosing braided channels. Water is stored within the subglacial system itself (till, braided system and ‘ponds’), allowing the rapid access of water to enable glacier speed-up events to occur throughout the year, particularly in winter.

scholarly journals The Seasonal Evolution of Subglacial Drainage Pathways Beneath a Soft-bedded Glacier

2021 ◽  
Author(s):  
Jane K. Hart ◽  
David S. Young ◽  
Nathaniel R. Baurley ◽  
Benjamin A. Robson ◽  
Kirk Martinez
Keyword(s):  
Climate Change ◽  
Sediment Layer ◽  
Seasonal Evolution ◽  
Rapid Access ◽  
Speed Up ◽  
Self Organizing ◽  
Subglacial Drainage

Abstract Subglacial hydrology is a key element in glacier response to climate change, but investigations of this environment are logistically difficult. Most models are based on summer data from glaciers resting on rigid bedrocks. However a significant number of glaciers rest on soft (unconsolidated sedimentary) beds. Here we present a unique multi-year instrumented record of the development of seasonal subglacial behavior associated with an Icelandic temperate glacier resting on a deformable sediment layer. We observe a distinct annual pattern in the subglacial hydrology based on self-organizing anastomosing braided channels. Water is stored within the subglacial system itself (till, braided system and ‘ponds’), allowing the rapid access of water to enable glacier speed-up events to occur throughout the year, particularly in winter.

scholarly journals Radar studies at the mouths of ice streams D and E, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 262-268 ◽  
Author(s):  
Robert W. Jacobel ◽  
Robert Bindschadler
Keyword(s):  
Climate Change ◽  
Surface Topography ◽  
Satellite Imagery ◽  
Ice Thickness ◽  
West Antarctica ◽  
Ice Streams ◽  
The West ◽  
Mass Balance Calculation ◽  
Grounding Line ◽  
Thickness Measurements

Ice thickness measurements have been carried out at the mouths of ice streams D and E, West Antarctica using a surface-based impulse radar. These studies have been undertaken as a part of the continuing effort to understand the state of the West Antarctica ice sheet and its response to climate change. Thickness measurements will be used in the mass balance calculation currently in progress and to better understand features in the surface topography seen at low angle sun illumination in the satellite imagery. Results show that the discharge areas of ice streams D and E are thickening by approximately 1 m per year, and thus that these ice streams are probably loosing mass. Aperiodic wavelike features in the surface topography are described which pose interesting questions about migration of the grounding line and ice-stream dynamics.

scholarly journals Radar studies at the mouths of ice streams D and E, Antarctica

1993 ◽  
Vol 17 ◽  
pp. 262-268 ◽  
Author(s):  
Robert W. Jacobel ◽  
Robert Bindschadler
Keyword(s):  
Climate Change ◽  
Surface Topography ◽  
Satellite Imagery ◽  
Ice Thickness ◽  
West Antarctica ◽  
Ice Streams ◽  
The West ◽  
Mass Balance Calculation ◽  
Grounding Line ◽  
Thickness Measurements

Ice thickness measurements have been carried out at the mouths of ice streams D and E, West Antarctica using a surface-based impulse radar. These studies have been undertaken as a part of the continuing effort to understand the state of the West Antarctica ice sheet and its response to climate change. Thickness measurements will be used in the mass balance calculation currently in progress and to better understand features in the surface topography seen at low angle sun illumination in the satellite imagery. Results show that the discharge areas of ice streams D and E are thickening by approximately 1 m per year, and thus that these ice streams are probably loosing mass. Aperiodic wavelike features in the surface topography are described which pose interesting questions about migration of the grounding line and ice-stream dynamics.

scholarly journals Flow-switching and water piracy between Rutford Ice Stream and Carlson Inlet, West Antarctica

2008 ◽  
Vol 54 (184) ◽  
pp. 41-48 ◽  
Author(s):  
David G. Vaughan ◽  
Hugh F.J. Corr ◽  
Andy M. Smith ◽  
Hamish D. Pritchard ◽  
Andrew Shepherd
Keyword(s):  
Indirect Evidence ◽  
West Antarctica ◽  
Ice Streams ◽  
Ice Flow ◽  
Stream Flows ◽  
Current State ◽  
Ice Stream ◽  
State Of Water ◽  
Almost All ◽  
Subglacial Drainage

AbstractRutford Ice Stream and Carlson Inlet are neighbouring glaciers in West Antarctica. Rutford Ice Stream flows at speeds greater than 350 m a−1, whereas Carlson Inlet, which has some similar dimensions and supports a similar driving stress, flows 10–50 times slower. We discuss a range of observations concerning Carlson Inlet, and conclude that there is good indirect evidence that it is a relict ice stream, which ceased streaming more than 240 years BP, but sufficiently recently that its surface morphology, basal water content and basal morphology still retain characteristics produced by streaming. An analysis of expected subglacial drainage pathways indicates that Carlson Inlet is not streaming because it is currently starved of subglacial water, which is currently directed beneath Rutford Ice Stream. This current state of water piracy by Rutford Ice Stream is, however, sensitive to minor thickness changes on the ice streams; a ∼120 m (<4%) thickening of Rutford Ice Stream would divert almost all the subglacial water in the system towards Carlson Inlet and could reactivate its flow. The result highlights the importance of subglacial drainage in controlling ice-stream evolution and the requirement for ice-sheet models to couple ice flow with subglacial drainage.

scholarly journals Of isbræ and ice streams

2003 ◽  
Vol 36 ◽  
pp. 66-72 ◽  
Author(s):  
Martin Truffer ◽  
Keith A. Echelmeyer
Keyword(s):  
Ice Sheet ◽  
Shear Zones ◽  
West Antarctica ◽  
Ice Streams ◽  
Ice Flow ◽  
Bed Topography ◽  
Ice Stream ◽  
Fast Ice ◽  
Fast Flow ◽  
End Members

AbstractFast-flowing ice streams and outlet glaciers provide the major avenues for ice flow from past and present ice sheets. These ice streams move faster than the surrounding ice sheet by a factor of 100 or more. Several mechanisms for fast ice-stream flow have been identified, leading to a spectrum of different ice-stream types. In this paper we discuss the two end members of this spectrum, which we term the “ice-stream” type (represented by the Siple Coast ice streams in West Antarctica) and the “isbræ” type (represented by Jakobshavn Isbræ in Greenland). The typical ice stream is wide, relatively shallow (∼1000 m), has a low surface slope and driving stress (∼10 kPa), and ice-stream location is not strongly controlled by bed topography. Fast flow is possible because the ice stream has a slippery bed, possibly underlain by weak, actively deforming sediments. The marginal shear zones are narrow and support most of the driving stress, and the ice deforms almost exclusively by transverse shear. The margins seem to be inherently unstable; they migrate, and there are plausible mechanisms for such ice streams to shut down. The isbræ type of ice stream is characterized by very high driving stresses, often exceeding 200 kPa. They flow through deep bedrock channels that are significantly deeper than the surrounding ice, and have steep surface slopes. Ice deformation includes vertical as well as lateral shear, and basal motion need not contribute significantly to the overall motion. The marginal shear zone stend to be wide relative to the isbræ width, and the location of isbræ and its margins is strongly controlled by bedrock topography. They are stable features, and can only shut down if the high ice flux cannot be supplied from the adjacent ice sheet. Isbræs occur in Greenland and East Antarctica, and possibly parts of Pine Island and Thwaites Glaciers, West Antarctica. In this paper, we compare and contrast the two types of ice streams, addressing questions such as ice deformation, basal motion, subglacial hydrology, seasonality of ice flow, and stability of the ice streams.

scholarly journals Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes

2013 ◽  
Vol 54 (64) ◽  
pp. 105-114 ◽  
Author(s):  
S.R. Harland ◽  
J.-M. Kendall ◽  
G.W. Stuart ◽  
G.E. Lloyd ◽  
A.F. Baird ◽  
...  
Keyword(s):  
Shear Wave ◽  
Flow Direction ◽  
Transversely Isotropic ◽  
Shear Wave Splitting ◽  
Ice Crystal ◽  
West Antarctica ◽  
Ice Streams ◽  
Ice Flow ◽  
Ice Stream ◽  
Wave Splitting

Abstract Ice streams provide major drainage pathways for the Antarctic ice sheet. The stress distribution and style of flow in such ice streams produce elastic and rheological anisotropy, which informs ice-flow modelling as to how ice masses respond to external changes such as global warming. Here we analyse elastic anisotropy in Rutford Ice Stream, West Antarctica, using observations of shear-wave splitting from three-component icequake seismograms to characterize ice deformation via crystal-preferred orientation. Over 110 high-quality measurements are made on 41 events recorded at five stations deployed temporarily near the ice-stream grounding line. To the best of our knowledge, this is the first well-documented observation of shear-wave splitting from Antarctic icequakes. The magnitude of the splitting ranges from 2 to 80 ms and suggests a maximum of 6% shear-wave splitting. The fast shear-wave polarization direction is roughly perpendicular to ice-flow direction. We consider three mechanisms for ice anisotropy: a cluster model (vertical transversely isotropic (VTI) model); a girdle model (horizontal transversely isotropic (HTI) model); and crack-induced anisotropy (HTI model). Based on the data, we can rule out a VTI mechanism as the sole cause of anisotropy – an HTI component is needed, which may be due to ice crystal a-axis alignment in the direction of flow or the alignment of cracks or ice films in the plane perpendicular to the flow direction. The results suggest a combination of mechanisms may be at play, which represent vertical variations in the symmetry of ice crystal anisotropy in an ice stream, as predicted by ice fabric models.

The Changing Ethics of Climate Change

2014 ◽  
Vol 28 (3) ◽  
pp. 351-358 ◽  
Author(s):  
Daniel Mittler
Keyword(s):  
Climate Change ◽  
Power Plant ◽  
Moral Obligation ◽  
Environmental Movement ◽  
Health Problems ◽  
Renewable Energies ◽  
Car Use ◽  
The Face ◽  
Speed Up ◽  
The Right

Many in the environmental movement have argued in recent years that in order to speed up climate actions we should take the ethics out of the climate change debate. Focusing on the moral obligation to act or on the effects of climate change on the most vulnerable was often judged to render the discourse too “heavy,” “negative,” or “difficult.” Many also deemed it unnecessary. After all, renewable energies, better designed cities that allow for reduced car use, and power plant regulations that lead to cleaner local air—to take just three examples—all have real and substantial benefits unrelated to the fact that they are “the right thing to do” in the face of climate change. They create jobs, reduce health problems and costs, and make society fitter.

scholarly journals Machine Learning Speeding Up the Development of Portfolio of New Crop Varieties to Adapt to and Mitigate Climate Change

2021 ◽  
Author(s):  
Abdallah Bari ◽  
Hassan Ouabbou ◽  
abderrazek Jilal ◽  
Hamid Khazaei ◽  
Fred Stoddard ◽  
...  
Keyword(s):  
Climate Change ◽  
Machine Learning ◽  
Crop Varieties ◽  
Short Period ◽  
Speed Up ◽  
Increasing Demand ◽  
Mitigate Climate Change ◽  
High Yielding Varieties ◽  
New Crop ◽  
Adaptation And Mitigation

Climate change poses serious challenges to achieving food security in a time of a need to produce more food to keep up with the worlds increasing demand for food. There is an urgent need to speed up the development of new high yielding varieties with traits of adaptation and mitigation to climate change. Mathematical approaches, including ML approaches, have been used to search for such traits, leading to unprecedented results as some of the traits, including heat traits that have been long sought-for, have been found within a short period of time.

scholarly journals Significant submarine ice loss from the Getz Ice Shelf, Antarctica

2018 ◽  
Author(s):  
David M. Rippin
Keyword(s):  
Mass Loss ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Shelves ◽  
Warming Climate ◽  
Circulation Patterns ◽  
Direct Measurements ◽  
Radio Echo Sounding ◽  
The Impact

Abstract. We present the first direct measurements of changes taking place at the base of the Getz Ice Shelf (GzIS) in West Antarctica. Our analysis is based on repeated airborne radio-echo sounding (RES) survey lines gathered in 2010 and 2014. We reveal that while there is significant variability in ice shelf behaviour, the vast majority of the ice shelf (where data is available) is undergoing basal thinning at a mean rate of nearly 13 m a−1, which is several times greater than recent modelling estimates. In regions of faster flowing ice close to where ice streams and outlet glaciers join the ice shelf, significantly greater rates of mass loss occurred. Since thinning is more pronounced close to faster-flowing ice, we propose that dynamic thinning processes may also contribute to mass loss here. Intricate sub-ice circulation patterns exist beneath the GzIS because of its complex sub-ice topography and the fact that it is fed by numerous ice streams and outlet glaciers. It is this complexity which we suggest is also responsible for the spatially variable patterns of ice-shelf change that we observe. The large changes observed here are also important when considering the likelihood and timing of any potential future collapse of the ice shelf, and the impact this would have on the flow rates of feeder ice streams and glaciers, that transmit ice from inland Antarctica to the coast. We propose that as the ice shelf continues to thin in response to warming ocean waters and climate, the response of the ice shelf will be spatially diverse. Given that these measurements represent changes that are significantly greater than modelling outputs, it is also clear that we still do not fully understand how ice shelves respond to warming ocean waters. As a result, ongoing direct measurements of ice shelf change are vital for understanding the future response of ice shelves under a warming climate.

scholarly journals An improved bathymetry compilation for the Bellingshausen Sea, Antarctica, to inform ice-sheet and ocean models

2010 ◽  
Vol 4 (4) ◽  
pp. 2079-2101 ◽  
Author(s):  
A. G. C. Graham ◽  
F. O. Nitsche ◽  
R. D. Larter
Keyword(s):  
Ocean Circulation ◽  
Ice Sheet ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Streams ◽  
Ice Shelves ◽  
Sea Floor ◽  
Bellingshausen Sea ◽  
Warm Deep Water ◽  
Basal Melting

Abstract. The southern Bellingshausen Sea (SBS) is a rapidly-changing part of West Antarctica, where oceanic and atmospheric warming has led to the recent basal melting and break-up of the Wilkins ice shelf, the dynamic thinning of fringing glaciers, and sea-ice reduction. Accurate sea-floor morphology is vital for understanding the continued effects of each process upon changes within Antarctica's ice sheets. Here we present a new bathymetric grid for the SBS compiled from shipborne echo-sounder, spot-sounding and sub-ice measurements. The 1-km grid is the most detailed compilation for the SBS to-date, revealing large cross-shelf troughs, shallow banks, and deep inner-shelf basins that continue inland of coastal ice shelves. The troughs now serve as pathways which allow warm deep water to access the ice fronts in the SBS. Our dataset highlights areas still lacking bathymetric constraint, as well as regions for further investigation, including the likely routes of palaeo-ice streams. The new compilation is a major improvement upon previous grids and will be a key dataset for incorporating into simulations of ocean circulation, ice-sheet change and history. It will also serve forecasts of ice stability and future sea-level contributions from ice loss in West Antarctica, required for the next IPCC assessment report in 2013.

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