In 2010, the IPCC highlighted the disagreement in ice sheet mass balance estimates as a primary emerging topic (Stocker et al., 2010). They expressed concern that progress would not be made in the run up to the fifth assessment report and noted the potential value of inter-comparison projects for addressing the problem (Stocker et al., 2010).
The Ice sheet Mass Balance Inter-comparison Exercise (IMBIE) was established with the aim of providing reconciled estimates of ice sheet mass balance. In 2012, IMBIE achieved this aim and reconciled measurements of ice sheet mass balance using satellite altimetry, gravimetry and the input-output method (Shepherd et al., 2012).
Through a series of experiments that used common spatial definitions and time periods, and that investigated the impacts of various ancillary datasets used, it was shown that there is good agreement between estimates of Antarctic and Greenland mass balance determined from the three techniques. The project highlighted the complementary nature of the three approaches, showing that by combining techniques, the coverage and confidence of the results is improved.
(Photo credit: Ian Joughin)