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Mass balance estimates for the Antarctic Ice Sheet (AIS) in the 2007 report by the Intergovernmental Panel on Climate Change and in more recent reports lie between approximately ?50 to -250 Gt/year for 1992 to 2009. The 300 Gt/year range is approximately 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (?28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. We also modify the IOM estimate using (1) an alternate extrapolation to estimate the discharge from the non-observed 15% of the periphery, and (2) substitution of input from a field data compilation for input from an atmospheric model in 6% of area. The modified IOM estimate reduces the loss from 136 Gt/year to 13 Gt/year. Two ERS-based estimates, the modified IOM, and a GRACE-based estimate for observations within 1992-2005 lie in a narrowed range of ?27 to -40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992-2001 is -47 Gt/year for West Antarctica, ?16 Gt/year for East Antarctica, and -31 Gt/year overall (?0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07% of the AIS area). Although recent reports of large and increasing rates of mass loss with time from GRACE-based studies cite agreement with IOM results, our evaluation does not support that conclusion.

The latest compilations of surface mass balance, mean annual surface temperature, and elevation for the Antarctic ice sheet, derived from data sets of approximately 1500, 700, and 105 points, respectively, have been used to obtain areally integrated means for 24 ice drainage systems and 329 grid point values covering the whole ice sheet. Monthly summaries of remotely sensed sea ice data for 1973–1976 have been used to obtain mean annual distance to open ocean. Linear and second‐order regression analyses of surface balance on (1) temperature for the entire ice sheet, (2) elevation for the conterminous grounded ice, and (3) distance to the open ocean for the ice shelves (including ice rises and attached islands) have been made using both system means and grid point values. These analyses show correlation coefficients of between 0.63 and 0.81, and they provide bases for descriptive models of the present Antarctic ice sheet, as well as for predictive models of the response of the ice sheet to air temperature changes and variations in meridional mass and energy transfers. Extrapolation to other ice sheets, past and present, may be possible but should be made cautiously. Linear models are recommended for paleoclimatic reconstructions of ice sheets in upper mid‐latitudes, and second‐order models are recommended for those in high latitudes. System means are shown to be reliable for these purposes. Incidental results are new estimates of the mean annual surface temperature for the whole ice sheet (−36°C) and mean surface elevation for the conterminous grounded ice (2290 m).

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The annual net atmospheric transports of water vapor and latent heat poleward across 70°S are estimated using the latest compilation of surface mass balance for the Antarctic ice sheet and new estimates of precipitation and evaporation in sectors of the southern oceans and of seaward drifting snow transport in particular sectors of the ice sheet. The mass and energy exchange rates at the ice sheet‐atmosphere and ocean‐atmosphere interfaces are integrated strictly for areas within that latitude. The estimates of net southward water vapor transport (6.6 ± 1.3 kg m−1 s−1) and latent heat transport (18.9 ± 3.6 MJ m−1 s−1) are larger than reported in all preceding studies, based on atmospheric advection and moisture data collected at stations located between 66°S and 80°S, and are generally in agreement with those based on surface mass balance data and seaward drifting snow transport across the ice terminus which extends between 65°S and 79°S.

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