What is IMBIE?

The ice sheet mass balance inter-comparison exercise (IMBIE) was established in 2011 as a community effort to reconcile satellite measurements of ice sheet mass balance. IMBIE is a collaboration between scientists supported by the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA), and contributes to assessment reports of the Intergovernmental Panel on Climate Change (IPCC). 

IMBIE was established with the aim of providing reconciled estimates of ice sheet mass balance. In 2012, IMBIE achieved this aim, reconciling existing measurements using satellite altimetry, gravimetry and the input-output method (Shepherd et al., 2012).  It showed a good agreement between estimates of Antarctic and Greenland mass balance determined from the three techniques, and also improved the coverage and confidence of results. 

IMBIE has led to improved confidence in the measurement of ice sheet mass balance and the associated global sea-level contribution. The improvements were achieved through combination of ice sheet imbalance estimates developed from the independent satellite techniques of altimetry, gravimetry and the input-output method. Going forwards, IMBIE provides a framework for assessing ice sheet mass balance, and has an explicit aim to widen participation to enable the entire scientific community to become involved. 

Fluctuations in the mass of the Greenland and Antarctic ice sheets are of considerable societal importance as they impact directly on global sea levels: since 1901, ice losses from Antarctica and Greenland, alongside the melting of small glaciers and ice caps and thermal expansion of the oceans, have caused global sea levels to rise at an average rate of 1.7 mm/yr. 

Between 1992 and 2010 the rate of change, as measured by satellite altimetry and tide gauges, reached 3.2mm/yr. This translates as a total rise of 0.19 m in global mean sea level since the turn of the twentieth century. 
(http://imbie.org/)