IMBIE project press release
**Strictly embargoed until Thursday 29 November 1400h US Eastern Time / 1900h UK
Time**
Clearest evidence yet of polar ice losses
An international team of satellite experts has produced the most accurate assessment of ice
losses from Antarctica and Greenland to date, ending 20-years of uncertainty.
In a landmark study, published on 30 November in the journal Science, the researchers
show that melting of the Antarctic and Greenland ice sheets has contributed 11.1 millimetres
to global sea levels since 1992. This amounts to one fifth of all sea level rise over the survey
period.
About two thirds of the ice loss was from Greenland, and the remainder was from Antarctica.
Although the ice sheet losses fall within the range reported by the IPCC in 2007, the spread
of the IPCC estimate was so broad that it was not clear whether Antarctica was growing or
shrinking. The new estimates are a vast improvement (more than twice as accurate) thanks
to the inclusion of more satellite data, and confirm that both Antarctica and Greenland are
losing ice.
The study also shows that the combined rate of ice sheet melting has increased over time
and, altogether, Greenland and Antarctica are now losing more than three times as much ice
(equivalent to 0.95 mm of sea level rise per year) as they were in the 1990s (equivalent to
0.27 mm of sea level rise per year).
The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) is a collaboration between
47 researchers from 26 laboratories, and was supported by the European Space Agency
(ESA) and the National Aeronautics and Space Administration (NASA).
Led by Professor Andrew Shepherd at the University of Leeds and Dr Erik Ivins at NASA’s
Jet Propulsion Laboratory, the study combines observations from 10 different satellite
missions to develop the first consistent measurement of polar ice sheet changes.
The researchers were able to reconcile the differences between dozens of earlier ice sheet
studies through careful use of matching time periods and survey areas, and by combining
measurements collected by different types of satellites.
Professor Shepherd, who coordinated the study, said: "The success of this venture is due to
the cooperation of the international scientific community, and due to the provision of precise
satellite sensors by our space agencies. Without these efforts, we would not be in a position
to tell people with confidence how the Earth's ice sheets have changed, and to end the
uncertainty that has existed for many years."
The study also found differences in the pace of change at each pole.
Dr Ivins, who also coordinated the project, said: "The rate of ice loss from Greenland has
increased almost five-fold since the mid-1990s. In contrast, while the regional changes in
Antarctic ice over time are sometimes quite striking, the overall balance has remained fairly
constant - at least within the certainty of the satellite measurements we have to hand."
Commenting on the findings, Professor Richard Alley, a climate scientist at Penn State
University who was not involved in the study, said: "This project is a spectacular
achievement. The data will support essential testing of predictive models, and will lead to a
better understanding of how sea-level change may depend on the human decisions that
influence global temperatures."
‘A reconciled estimate of ice sheet mass balance’ by Prof Shepherd et al is published in
Science on 30 November 2012, DOI: 10.1126/science.1228102. For a copy of the paper
please visit the website http://www.eurekalert.org/jrnls/sci/ (access granted to journalists
registered with Science) or contact the Science press team, phone +1 202-326-6440 or
email scipak@aaas.org
Further information:
To request an interview with Prof Andrew Shepherd, School of Earth & Environment,
University of Leeds, please contact Esther Harward, University of Leeds Communications
Office, phone +44 113 343 4196 or email e.harward@leeds.ac.uk
The following restricted access website contains more information about the study, including
images and multimedia for journalists to download: www.imbie.org/news/press. Password:
penguin
Notes to Editors:
1. The ten satellite missions providing data for this study are the first and second ESA
European Remote Sensing satellites (ERS-1 and ERS-2); the Japan Aerospace Exploration
Agency (JAXA) Advanced Land Observatory System (ALOS) ; the Canadian Space Agency
(CSA) RADARSAT-1 and RADARSAT-2 satellites; the NASA Ice, Cloud, and land Elevation
Satellite (ICESat); the ESA Envisat satellite; the NASA / German Aerospace Center (DLR)
Gravity Recovery and Climate Experiment (GRACE); the Italian Space Agency (ASI)
COSMO-SkyMed satellite, and the DLR TerraSAR-X satellite.
2. IMBIE was created by ESA and NASA. The study was also supported by a Phillip
Leverhulme Prize awarded to Professor Andy Shepherd, the EU FP7 ice2sea program, the
Lamont Doherty Earth Observatory, the Netherlands Organization for Scientific Research,
the Netherlands Polar Program, the UK Natural Environment Research Council, and the US
National Science Foundation.
3. [insert individual boiler plates, e.g. The 2008 Research Assessment Exercise showed the
University of Leeds to be the UK's eighth biggest research powerhouse. The University is
one of the largest higher education institutions in the UK and a member of the Russell Group
of research-intensive universities. The University's vision is to secure a place among the
world's top 50 by 2015. Earth Sciences at the University of Leeds was ranked 42nd in the QS
World University Rankings 2012/13. www.leeds.ac.uk.]