Estimating the contribution of ice sheets to sea level change is a major goal of glaciologists. For this purpose we analyse altimeter data of different satellite-borne satellites and estimate by this the volume change, the first major step towards mass change estimates. For the assessment of the contribution of ice sheets to sea level change robust, consistent processing, as well as the estimation of uncertainties is important. There are numerous sources for uncertainty, ranging from instrumental errors towards the interpolation between sparsely distributed data. Here, we aim to present a time series of the volumetric change using different sensors and different interpolation techniques. This presentation focuses on the present-day ice-volume changes of the Greenland and Antarctic ice sheets. Based on four years (January 2011 to January 2015) of CryoSat-2 data acquisition we derived elevation change maps and volume change estimates for both ice sheets. We will present a set of estimates derived from different interpolation methods. Additional we will compare our results to elevation change rates obtained from ICESat data covering the time period from 2003 to 2009. In contrast to our study of last year we extented the time series of CryoSat-2 by one year and used the new data release 34 of ICESat. The new results will be presented and compared.