Martin J. Siegert and the Lake Ellsworth consortium

1
Martin J. Siegert and the Lake Ellsworth
consortium

• The exploration of subglacial Lake Ellsworth,
  West Antarctica
• SALE, Vienna, April 2005

2
Contents

• Subglacial Lake Ellsworth
• New data
• Geophysical survey
• Plans for exploration
• Timetable for activity IPY and beyond

3
(No Transcript)
4
Lake Ellsworth

• Several lines of evidence reveal the existence of
  Lake Ellsworth
• RES data are limited to 4 lines One line is old,
  three lines are new

5
RES data
6
(No Transcript)
7
New RES data
8
Thermodynamic calculations

• Lake is near an ice divide use 1D eq. to
  calculate Geothermal heat
• Present day temp -30C, accumulation of 17 cm/y
  52 mW m-2
• LGM Huybrechts (2002) ice thickness 250 m, temp
  -8ºC, accumulation 50 46.72 mW m-2
• Basal heat flux calculated in West Antarctica
  from temperature gradients in boreholes is 70 mW
  m-2
• Hence, basal heating at the level expected is
  sufficient for the subglacial lake to exist both
  during the present interglacial and at the LGM

9
these observations rule out the existence of a
frozen lake or a grounded ice base they can
only be explained by the presence of a subglacial
lake
10
Advantages of Lake Ellsworth for exploration

• Lake Ellsworth is located 20 km from an ice
  divide
• The lake is relatively small
• Lake Ellsworth is enclosed topographically
• The lake is within BAS logistical coverage
• The ice-sheet surface is 2000 m above sea level
• Numerous occasions when the base of WAIS has been
  reached, sampled and measured
• Sediments across the lake floor may contain a
  unique record of WAIS history

11
Geophysical surveyTwo airborne RES lines
2004-5.Full season of IPR, GPR, Seismics and
surface measurements, 2006-7.Short season of
surface measurements, 2007-8.Will be the best
characterised subglacial lake within 4 years.
12
Plans for coordination of direct measurement and
sampling
UK-led consortium, involving 25 scientists from
12 UK Institutions. Geophysicists,
microbiologists, glaciologists, biogeochemists,
oceanographers, astrobiologists, space
scientists, technologists, geologists, geofluids
experts. US involvement from Montana State
University, and scientists from Belgium, Germany,
New Zealand and Sweden.
13
Lake Ellsworth consortium

• Three meetings have been held to assemble the UK
  community and plan the exploration programme
  (concentrating on first access)
• www.ggy.bris.ac.uk/ellsworth website is part of
  an open and transparent policy. All details of
  meetings available here
• Concept document has been written (circulated)
• Now in a position to seek funding

14
Plan for exploration

• Hot-water drilling to lake
• Hole open for 24-36 hours
• Deploy probe
• Measurements on way down
• Water samples and more measurements on way up
• Recover probe
• Deploy gravity core for lake floor sediments
• Deploy permanent station

15
Timeline for activity

• 22 Nov 04 Submitted proposal for comprehensive
  geophysical survey of the lake.
• 20 Dec 04 Concept document written
• 14 Jan 05 IPY expression of intent submitted.
• 8 March 05 3rd Ellsworth meeting, BAS
• 30 March 05 Decision on geophysical survey
• Easter 05. Revise IPY plan into full IPY
  proposal
• June 05 IPY decisions on programme.
• 1 July 05 Submit full UK-led project to RCs ?
• 2006-7 Comprehensive survey of lake
• 2007-8 Instrument development and testing
• 2008-9 Lake exploration

16
International Polar YearSALE-UNITED
17
Summary

• Lake Ellsworth is identified as a 10 km long
  subglacial lake in West Antarctica
• Several reasons for why this lake is a good
  candidate for exploration
• Consortium configured to plan for exploration
  during IPY
• Geophysics survey prior to IPY
• Exploration is possible by the end of the decade

18
(No Transcript)