EUROPEAN GEOSCIENCES UNION & BRITISH ANTARCTIC SURVEY
PRESS RELEASE
EMBARGOED UNTIL 13 MAY 2015 AT 01:01 CEST
New study shows Antarctic ice shelf is thinning from above and below
A decade-long scientific debate about what’s causing the thinning of one of Antarctica’s largest ice shelves has
now been settled. The Larsen C Ice Shelf – whose neighbours Larsen A and B collapsed in 1995 and 2002 – is
thinning from both its surface and beneath. The research, by scientists from the UK and the US, is published
today (Wednesday 13 May) in The Cryosphere, an open access journal of the European Geosciences Union
(EGU).
For years scientists were unable to determine whether it is warming air temperatures or warmer ocean currents that is
causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse. This
new study takes an important step forward in assessing Antarctica’s likely contribution to future sea-level rise.
The research team combined satellite data and eight radar surveys captured during a 15-year period from 1998–2012.
They found that Larsen C Ice Shelf, which is some 50,000 km2 in area or about half the size of Iceland, lost an
average of four metres of ice, and had lowered by an average of one metre at the surface.
Lead author Paul Holland, a climate scientist at the British Antarctic Survey, says: “What’s exciting about this study is
we now know that two different processes are causing Larsen C to thin and become less stable. Air is being lost from
the top layer of snow (called the firn), which is becoming more compacted – probably because of increased melting by
a warmer atmosphere. We know also that Larsen C is losing ice, probably from warmer ocean currents or changing
ice flow.
“If this vast ice shelf – which is over two and a half times the size of Wales and 10 times bigger than Larsen B – was
to collapse, it would allow the tributary glaciers behind it to flow faster into the sea. This would then contribute to sealevel rise.”
The Antarctic Peninsula is one of the fastest warming regions on Earth, with a temperature rise of 2.5°C over the last
50 years.
The team, who continue to monitor the ice shelf closely, predict that a collapse could occur within a century, although
maybe sooner and with little warning. A crack is forming in the ice which could cause it to retreat back further than
previously observed. The ice shelf appears also to be detaching from a small island called Bawden Ice Rise at its
northern edge.
Glaciologist David Vaughan, Director of Science at British Antarctic Survey, says: “When Larsen A and B were lost,
the glaciers behind them accelerated and they are now contributing a significant fraction of the sea-level rise from the
whole of Antarctica. Larsen C is bigger and if it were to be lost in the next few decades then it would actually add to
the projections of sea-level rise by 2100.
“We expect that sea-level rise around the world will be something in excess of 50 cm higher by 2100 than it is at
present and that will cause problems for coastal and low-lying cities. Understanding and counting up these small
contributions from Larsen C and all the glaciers around the world is very important if we are to project, with
confidence, the rate of sea-level rise into the future.”
The study published today in The Cryosphere was carried out by scientists from the British Antarctic Survey, the
United States Geological Survey, University of Colorado, University of Kansas and Scripps Institution of
Oceanography.
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Please mention the name of the publication (The Cryosphere) if reporting on this story and, if reporting
online, include a link to the paper (TBA) or to the journal website (http://www.the-cryosphere.net).
Photos of the Larsen C ice shelf, as well as interviews with Paul Holland and David Vaughan, are available
from the British Antarctic Survey ftp site.
Notes
The Antarctic Peninsula is an area of rapid climate change and has shown one of the biggest increases in
temperatures (primarily in winter) observed anywhere on Earth over the past half-century. Climate records
from the west coast of the Antarctic Peninsula show that mean annual temperatures in this region have
risen by 2.5°C during the last 50 years – several times the global average and only matched in Alaska.
An ice shelf is the floating extension of the grounded ice sheet. It is composed of freshwater ice that
originally fell as snow, either in situ or inland and brought to the ice shelf by glaciers. As they are already
floating, any disintegration of ice shelves will have no impact on sea level. Sea level will rise only if the ice
held back by the ice shelf flows more quickly into the sea.
More information
This is an edited version of a release provided by the British Antarctic Survey Press Office. The research is
presented in the paper ‘Oceanic and atmospheric forcing of Larsen C ice-shelf thinning’ to appear in the
EGU open access journal The Cryosphere on 13 May 2015.
The scientific article is available online, free of charge, from the morning of the publication date onwards, at
http://www.the-cryosphere.net/recent_papers.html. A pre-print version of the paper is available for
download at http://www.egu.eu/news/170/new-study-shows-antarctic-ice-shelf-is-thinning-from-above-andbelow/.
The team is composed of P.R. Holland, A. Brisbourne, H. F. J. Corr (British Antarctic Survey [BAS],
Cambridge, UK); D. McGrath (US Geological Survey Alaska Science Center and Cooperative Institute for
Research in Environmental Sciences, University of Colorado, Boulder, US); K. Purdon, J. Paden (Center
for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, US); H. A. Fricker, F. S. Paolo (Scripps
Institution of Oceanography, University of California, San Diego, US); and A. Fleming (BAS).
The work is funded by the Natural Environment Research Council in the UK, National Science Foundation
in the US and a range of international funding bodies around the world.
The European Geosciences Union (www.egu.eu) is Europe’s premier geosciences union, dedicated to
the pursuit of excellence in the Earth, planetary, and space sciences for the benefit of humanity, worldwide.
It is a non-profit interdisciplinary learned association of scientists founded in 2002. The EGU has a current
portfolio of 17 diverse scientific journals, which use an innovative open access format, and organises a
number of topical meetings, and education and outreach activities. Its annual General Assembly is the
largest and most prominent European geosciences event, attracting over 11,000 scientists from all over the
world. The meeting’s sessions cover a wide range of topics, including volcanology, planetary exploration,
the Earth’s internal structure and atmosphere, climate, energy, and resources. The EGU 2016 General
Assembly is taking place in Vienna, Austria, from 17 to 22 April 2016. For information about meeting and
press registration, please check http://media.egu.eu closer to the time of the conference or follow the EGU
on Twitter and Facebook.
British Antarctic Survey (BAS), a component of the UK’s Natural Environment Research Council
(NERC), delivers and enables world-leading interdisciplinary research in the Polar Regions. Its skilled
science and support staff based in Cambridge, Antarctica and the Arctic, work together to deliver research
that uses the Polar Regions to advance our understanding of Earth as a sustainable planet. Through its
extensive logistic capability and know-how BAS facilitates access for the British and international science
community to the UK polar research operation. Numerous national and international collaborations,
combined with an excellent infrastructure help sustain a world leading position for the UK in Antarctic
affairs. For more information visit: www.antarctica.ac.uk.
Contacts
Paul Holland
Climate Scientist, British Antarctic Survey
Cambridge, UK
Tel: +44 (0)1223 221444
Email: pahol@bas.ac.uk
David Vaughan
Director of Science
British Antarctic Survey
Email: dgv@bas.ac.uk
Athena Dinar
Press and Information Officer, British Antarctic Survey
Cambridge, UK
Tel: +44 (0)1223 221441, +44 (0)7909 008516
Email amdi@bas.ac.uk
BAS on Twitter: @BAS_News
Bárbara Ferreira
EGU Media and Communications Manager
Munich, Germany
Tel: +49-89-2180-6703
Email: media@egu.eu
EGU on Twitter: @EuroGeosciences
IMAGES
IMAGE 1:
Description:
BAS radar sledge on the Larsen Ice Shelf
Credit:
Adam Clark, British Antarctic Survey (BAS)
IMAGE 2:
Description:
BAS radar-equipped twin otter
Credit:
Rod Arnold, British Antarctic Survey (BAS)