Satellite observations of Antarctic sea ice thickness and volume

We utilize satellite laser altimetry data from NASA's Ice, Cloud, and land Elevation Satellite (ICESat) combined with passive microwave measurements to analyze basin‐wide changes in Antarctic sea ice thickness and volume over a 5 year period from 2003–2008. Sea ice thickness exhibits a small negative trend while area increases in the summer and fall balanced losses in thickness leading to small overall volume changes. Using a 5 year time series, we show that only small ice thickness changes of less than −0.03 m/yr and volume changes of −266 km3/yr and 160 km3/yr occurred for the spring and summer periods, respectively. These results are in stark contrast to the much greater observed losses in Arctic sea ice volume and illustrate the different hemispheric changes of the polar sea ice covers in recent years. The uncertainties in the calculated thickness and volume trends are large compared to the observed basin‐scale trends. This masks the determination of a long‐term trend or cyclical variability in the sea ice cover. It is found that lengthening of the observation time series along with better determination of the interannual variability of sea ice and snow densities will allow for a more statistically significant determination of long‐term sea ice thickness and volume trends in the Southern Ocean. Key Points First ever study of Southern Ocean sea ice thickness and volume changes Comparisons with available in situ data support the accuracy of the results There is relatively little change in sea ice thickness and volume in Southern Ocean