13 February 2013
WASHINGTON – Arctic sea ice volume has declined by 36 percent in the autumn and 9 percent in the winter between 2003 and 2012, an international team of scientists has discovered.
Researchers used new data from the European Space Agency’s CryoSat-2 satellite spanning 2010 to 2012, and data from NASA’s ICESat satellite from 2003 to 2008 to estimate the volume of sea ice in the Arctic.
They found that from 2003 to 2008, autumn volumes of ice averaged 11,900 cubic kilometers (2,855 cubic miles) But from 2010 to 2012, the average volume had dropped to 7,600 cu. km. (1,823 cu. mi.) a decline of 4,300 cu. km (1,032 cu. mi.) The average ice volume in the winter from 2003 to 2008 was 16,300 cu. km. (3,911 cu. mi.), dropping to 14,800 cu. km (3,551 cu. mi.) between 2010 and 2012 – a difference of 1,500 cu. km. (360 cu. mi.).
‘The data reveals that thick sea ice has disappeared from a region to the north of Greenland, the Canadian Archipelago, and to the northeast of Svalbard,’ says Dr Katharine Giles, a research fellow at the Centre for Polar Observation and Modelling at University College London (UCL) and a member of the scientific team.
Giles and her colleagues report their findings in a paper that has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. AGU has posted the manuscript online as an accepted article.
The findings confirm the continuing decline in Arctic sea-ice volume simulated by the Pan-Arctic Ice-Ocean Modelling and Assimilation System (PIOMAS), which estimates the volume of Arctic sea ice and had been checked using earlier submarine, mooring, and satellite observations until 2008.
Other satellites have already shown drops in the area covered by Arctic sea ice as the climate has warmed. Indeed, sea-ice extent reached a record minimum in September 2012. But CryoSat-2, launched in April 2010, differs in that it lets scientists estimate the volume of sea ice – a much more accurate indicator of the changes taking place in the Arctic.
‘While two years of CryoSat-2 data aren’t indicative of a long-term change, the lower ice thickness and volume in February and March 2012, compared with same period in 2011, may have contributed to the record minimum ice extent during the 2012 autumn,’ says Professor Christian Haas of York University, Canada Research Chair for Arctic Sea Ice Geophysics, co-author of the study and coordinator of the international CryoSat sea ice validation activities.
CryoSat-2 measures ice volume using a high-resolution synthetic aperture radar altimeter, which fires pulses of microwave energy down towards the ice. The energy bounces off both the top of sections of ice and the water in the cracks in between. The difference in height between these two surfaces let scientists calculate the volume of the ice cover.
The team confirmed CryoSat-2 estimates of ice volume using measurements from three independent sources – aircraft, moorings, and NASA’s Operation IceBridge.
The research was funded by the Natural Environment Research Council, the European Space Agency, the German Aerospace Center, Alberta Ingenuity, NASA, the Office of Naval Research and the National Science Foundation.
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“CryoSat-2 estimates of Arctic sea ice thickness and volume”
Seymour W. Laxon, Katharine A. Giles, Andy L. Ridout, Duncan J. Wingham, Rosemary Willatt
Centre for Polar Observation and Modelling, Department of Earth Sciences, University College London, London, UK;
European Space Agency, EOP-PY, ESTEC, Noordwijk, The Netherlands;
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA;
Axel Schweiger, Jinlun Zhang
Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, Washington, USA;
Department of Earth and Space Science and Engineering, York University, Toronto, Canada;
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA;
School of Computer, Math, and Natural Sciences, Morgan State University, Baltimore, Maryland, USA;
Earth System Science Interdis ciplinary Center, University of Maryland, College Park, Maryland, USA;Malcolm DavidsonEuropean Space Agency, EOP-PY, ESTEC, Noordwijk, The Netherlands.
Dr Katharine Giles of UCL is the lead scientific contact for this study, as the lead author, Professor Seymour Laxon of UCL, tragically died in early January. Dr Katharine Giles, +44 (0)776 525 2960,email@example.com
Professor Christian Haas of York University, Canada is the second contact 001 416 736 2100 x77705,firstname.lastname@example.org