008-commsenv.txt (3354B)
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