Summary
Estimates of sea ice thickness around Antarctica are particularly sparse due to the difficulty of accessing the continent (particularly during winter) and the lack of submarine data. However recent measurements of ice or snow freeboard, from both space-borne radar and laser, have demonstrated the potential to provide estimates of sea ice thickness in the Arctic. In the Antarctic, however, additional uncertainties, particularly related to snow loading, are present. We will describe both techniques and describe qualitatively the uncertainties in their retrievals. We also show initial comparisons of radar altimeter thickness estimates with ULS measurements of ice draft and thickness from the ASPeCt project. We then describe briefly the future schedule of space-borne observations and the opportunities for dedicated validation activities.