The Cryosphere

Surface photograph of an experiment and DEM of an experimental valley produced by stereo-photogrammetry

Abstract

Ice streams are corridors of fast-flowing ice that control mass transfers from continental ice sheets to oceans.Their flow speeds are known to accelerate and decelerate,their activity can switch on and off, and even their locationscan shift entirely. Our analogue physical experiments revealthat a life cycle incorporating evolving subglacial meltwaterrouting and bed erosion can govern this complex transitory behaviour. The modelled ice streams switch on and acceleratewhen subglacial water pockets drain as marginal outburst floods (basal decoupling). Then they decelerate when the lubricating water drainage system spontaneously organizes itself into channels that create tunnel valleys (partial basal recoupling). The ice streams surge or jump in location when these water drainage systems maintain low discharge but they ultimately switch off when tunnel valleys have expanded to develop efficient drainage systems. Beyond reconciling previously disconnected observations of modern and ancient ice streams into a single life cycle, the modelling suggests that tunnel valley development may be crucial in stabilizing portions of ice sheets during periods of climate change.

https://www.the-cryosphere.net/12/2759/2018/

Modelled subglacial floods and tunnel valleys control the life cycle of transitory ice streams

Lelandais, T., Ravier, É., Pochat, S., Bourgeois, O., Clark, C., Mourgues, R., & Strzerzynski, P., 2018.

Lelandais, T., Ravier, É., Pochat, S., Bourgeois, O., Clark, C., Mourgues, R., & Strzerzynski, P., 2018. Modelled subglacial floods and tunnel valleys control the life cycle of transitory ice streams. The Cryosphere, 12(8), 2759-2772.