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SUMMARY:Assessing the vulnerability of the Weddell Sea sector of West Anta
 rctic Ice Sheet to future changes - Martin Siegert (Imperial College)
DTSTART:20141126T163000Z
DTEND:20141126T173000Z
UID:TALK55320@talks.cam.ac.uk
CONTACT:Poul Christoffersen
DESCRIPTION:Institute and Möller Ice Streams (IMIS) drain 20% of the ice 
 from West Antarctica\, forming major contributors to the Weddell Sea Secto
 r (WSS) of Antarctica. Before 2010\, relative to the other major West Anta
 rctic drainage basins feeding the Ross and Amundsen Seas\, the WSS rated a
 s West Antarctica’s “pole of ignorance” concerning past and present 
 glaciological conditions and sensitivity to change. Underpinned by the hyp
 othesis that IMIS may be underlain by deformable marine sediments analogou
 s to the Siple Coast ice streams\, and may therefore be prone to similar i
 ce-dynamical\ninstabilities\, a comprehensive aerogeophysical survey of IM
 IS was undertaken in the austral summer 2010/11 under the auspices of NERC
 ’s Antarctic Funding Initiative. I will present a synthesis of\nfindings
  from the new data.\n\nWe now know that the lower portion of IMIS is under
 lain by a deep  basin filled with marine sediments and sloping inland\, re
 ndering much of the region vulnerable to the marine ice-sheet instability.
  Inland of the marine basin\, the subglacial terrain is composed of mixed 
 roughness. This reflects\, in part\, a significant tectonic signature of f
 aults\, structural lineaments and Jurassic intrusions likely emplaced duri
 ng opening of the Weddell Sea Rift. \n\nSuperimposed is a geomorphological
  signature testifying to the\nbasin’s experience of waxing and waning ic
 e cover over glacial cycles. An extensive plateau inland of the deep basin
  was likely created under ice-free conditions during the mid-Miocene (17-1
 5 Ma)\, while large channels cut into the bedrock testify to the presence 
 of thinner\, temperate ice cover which allowed supraglacial subglacial con
 nections during the Pliocene (5.3 – 2.6 Ma). \n\nToday the regional ice 
 cover is thinning steadily from the Last Glacial Maximum (20 ka). Patterns
  of englacial layering suggest that in the less topographically constraine
 d western and southern parts of IMIS the spatial configuration of ice has 
 changed considerably\, likely in response to thinning and increased ground
 ing of the Bungenstock Ice Rise and a proportional increased to drainage o
 f IMIS via Institute Ice Stream. Multiple lines of evidence show that IMIS
  is today underlain by a highly dynamic subglacial hydrological system whi
 ch may facilitate further changes to ice flow. Modelling suggests that of 
 all the WSS ice\nstreams\, IMIS may be particularly susceptible to conside
 rable change after only a projected moderate\nincrease in ice-shelf melt a
 t its grounding zone.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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