The US National Research Council advocated for including an ICESat follow-on mission as a Tier-1 mission in the recent ‘Decadal Survey’ to continue ICESat’s critical observations of the ice sheets and sea ice. ICESat, despite technical problems, has delivered unprecedented measurements of sea-ice elevation from which sea-ice freeboard and subsequently sea-ice thickness have been derived. Following these recommendations, the ICESat-2 mission is now under development for launch in 2015. In this presentation, we present the motivation for space-based laser altimetry, the science requirements for ICESat-2, the current concept for the ICESat-2 mission and its potential for sea-ice research.