7 research outputs found
Modelled subglacial floods and tunnel valleys control the life cycle of transitory ice streams
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 locations
can shift entirely. Our analogue physical experiments reveal
that a life cycle incorporating evolving subglacial meltwater
routing and bed erosion can govern this complex transitory
behaviour. The modelled ice streams switch on and accelerate
when 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