007-commsenv.txt (3366B)
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 is 6 reshaped and remolded by past ice moving the sediments along with 7 its flow. The sediment movement is also observed under current 8 glaciers, both the fast-moving ice streams of the Greenland and 9 Antarctic ice sheets, as well as smaller glaciers in the mountainous 10 areas of Alaska, northern Sweden, and elsewhere. The movement of 11 sediment could be important for the past progression of glaciations, 12 and how resilient marine-terminating ice streams are against sea-level 13 rise. 14 15 Today, the Nature-group journal Communications Earth & Environment 16 published my paper on sediment beneath ice. Together with co-authors 17 Liran Goren, University of the Negev (Israel), and Jenny Suckale, 18 Stanford University (California, USA), we present a new computer 19 model that simulates the coupled mechanical behavior of ice, sediment, 20 and meltwater. We calibrate the model against real materials, and 21 provide a way forward for including sediment transport in ice-flow 22 models. We also show that water-pressure variations with the right 23 frequency can create create very weak sections inside the bed, and 24 this greatly enhances sediment transport. I designed the freely-available 25 program cngf-pf for the simulations. 26 27 28 ## Abstract 29 30 Water pressure fluctuations control variability in sediment 31 flux and slip dynamics beneath glaciers and ice streams 32 33 Rapid ice loss is facilitated by sliding over beds consisting 34 of reworked sediments and erosional products, commonly referred 35 to as till. The dynamic interplay between ice and till reshapes 36 the bed, creating landforms preserved from past glaciations. 37 Leveraging the imprint left by past glaciations as constraints 38 for projecting future deglaciation is hindered by our incomplete 39 understanding of evolving basal slip. Here, we develop a continuum 40 model of water-saturated, cohesive till to quantify the interplay 41 between meltwater percolation and till mobilization that governs 42 changes in the depth of basal slip under fast-moving ice. Our 43 model explains the puzzling variability of observed slip depths 44 by relating localized till deformation to perturbations in 45 pore-water pressure. It demonstrates that variable slip depth 46 is an inherent property of the ice-meltwater-till system, which 47 could help understand why some paleo-landforms like grounding-zone 48 wedges appear to have formed quickly relative to current 49 till-transport rates. 50 51 52 ## Metrics 53 54 It is a substantial task to prepare a scientific publication. The 55 commit counts below mark the number of revisions done during 56 preparation of this paper: 57 58 - Main article text: 239 commits 59 - Supplementary information text: 35 commits 60 - Experiments and figures: 282 commits 61 - Simulation software: 354 commits 62 63 64 ## Links and references: 65 66 - Publication on journal webpage: 67 - Article PDF (?? MB): 68 - Supplementary information PDF (?? MB): 69 - Source code for producing figures: git://src.adamsgaard.dk/cngf-pf-exp1 70 - Simulation software: git://src.adamsgaard.dk/cngf-pf