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SUMMARY:Suppression of marine ice sheet instability - Dr Sam Pegler\, Appl
 ied Maths\, University of Leeds
DTSTART:20180615T103000Z
DTEND:20180615T113000Z
UID:TALK105892@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:A considerable proportion of the West Antarctic Ice Sheet sits
  on bedrock deep below sea level (an average depth of 1 km below sea level
 )\, forming a so-called marine ice sheet. The ice sheet thus lies partiall
 y submerged in the ocean\, with the buoyancy of the ocean threatening to u
 npeel the base of the ice sheet from the bedrock. Since the bedrock slopes
  upwards in the direction of flow (an effect of the isostatic depression o
 f the Antarctic continent by the ice sheet)\, the process of this unpeelin
 g -- or grounding-line retreat -- can be exacerbated by a positive feedbac
 k mechanism created by the increasing buoyancy force as the grounding line
  retreats\, a phenomenon known as the "Marine Ice Sheet Instability".  The
  collapse of regions of the ice sheet owing to this instability has the po
 tential to add metres to sea level over the course of the next few centuri
 es\, and is a key unknown in efforts to predict future contributions to se
 a-level rise. This talk will review theoretical analysis of this instabili
 ty and the associated extensional viscous thin-film theory\, and demonstra
 te the dynamics through a combination of asymptotic and numerical studies\
 , and laboratory experiments. The talk will continue by discussing an effe
 ct of the back force (buttressing) exerted by the floating sections of the
  ice sheet at its margins. It is shown that\, subject to critical conditio
 ns\, this effect will suppress instability.  
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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