Abstract. In order to derive long-term changes in sea-ice volume, a multi-decadal sea-ice thickness record is required. CryoSat-2 has showcased the potential of radar altimetry for sea-ice mass-balance estimation over the last years. However, precursor altimetry missions such as Envisat have not been exploited to the same extent so far. Combining both missions to acquire a decadal sea-ice volume data set requires a method to overcome the discrepancies due to different foot-print sizes from either pulse-limited or beam-sharpened radar echoes. In this study, we implemented an inter-mission consistent surface-type classi-5 fication scheme for both hemispheres, based on the waveform pulse peakiness, leading-edge width, and sea-ice backscatter.In order to achieve a consistent retracking procedure, we adapted the Threshold First Maximum Retracker Algorithm, previously used only for CryoSat-2, to develop an adaptive retracker threshold that depends on waveform characteristics. With our method, we produce a global and consistent freeboard data set for CryoSat-2 and Envisat. This novel data set features a maximum monthly difference in the mission-overlap period of 2.2 cm (2.7 cm) for the Arctic (Antarctic) based on all gridded 10 values with spatial resolution of 25 km × 25 km and 50 km × 50 km for the Arctic and Antarctic, respectively.