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t008-commsenv.txt (3354B)
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1 The majority of glaciers and ice sheets flow on a bed of loose and
2 thawed sediments. These sediments are weakened by pressurized glacial
3 meltwater, and their lubrication accelerates the ice movement. In
4 formerly-glaciated areas of the world, for example Northern Europe,
5 North America, and in the forelands of the Alps, the landscape was
6 reshaped and remolded by past ice moving the sediments along with
7 its flow. Sediment movement is also observed under current glaciers,
8 both the fast-moving ice streams of the Greenland and Antarctic ice
9 sheets, but also smaller glaciers in the mountainous areas of Alaska,
10 northern Scandinavia, and elsewhere. The movement of sediment could
11 be important for the progression of glaciations, and influence how
12 resilient marine-terminating ice streams are against sea-level rise.
13
14 Today, the Nature-group journal Communications Earth & Environment
15 published my paper on sediment beneath ice. Together with co-authors
16 Liran Goren, University of the Negev (Israel), and Jenny Suckale,
17 Stanford University (California, USA), we present a new computer
18 model that simulates the coupled mechanical behavior of ice, sediment,
19 and meltwater. We calibrate the model against real materials, and
20 provide a way for including sediment transport in ice-flow models.
21 We also show that water-pressure variations with the right frequency
22 can create create very weak sections inside the bed, and this greatly
23 enhances sediment transport. I designed the freely-available program
24 cngf-pf for the simulations.
25
26
27 ## Abstract
28
29 Water pressure fluctuations control variability in sediment
30 flux and slip dynamics beneath glaciers and ice streams
31
32 Rapid ice loss is facilitated by sliding over beds consisting
33 of reworked sediments and erosional products, commonly referred
34 to as till. The dynamic interplay between ice and till reshapes
35 the bed, creating landforms preserved from past glaciations.
36 Leveraging the imprint left by past glaciations as constraints
37 for projecting future deglaciation is hindered by our incomplete
38 understanding of evolving basal slip. Here, we develop a continuum
39 model of water-saturated, cohesive till to quantify the interplay
40 between meltwater percolation and till mobilization that governs
41 changes in the depth of basal slip under fast-moving ice. Our
42 model explains the puzzling variability of observed slip depths
43 by relating localized till deformation to perturbations in
44 pore-water pressure. It demonstrates that variable slip depth
45 is an inherent property of the ice-meltwater-till system, which
46 could help understand why some paleo-landforms like grounding-zone
47 wedges appear to have formed quickly relative to current
48 till-transport rates.
49
50
51 ## Metrics
52
53 It is a substantial task to prepare a scientific publication. The
54 commit counts below mark the number of revisions done during
55 preparation of this paper:
56
57 - Main article text: 239 commits
58 - Supplementary information text: 35 commits
59 - Experiments and figures: 282 commits
60 - Simulation software: 354 commits
61
62
63 ## Links and references:
64
65 - Publication on journal webpage (open access):
66 https://doi.org/10.1038/s43247-020-00074-7
67 - Source code for producing figures: git://src.adamsgaard.dk/cngf-pf-exp1
68 - Simulation software: git://src.adamsgaard.dk/cngf-pf