We have already mentioned the spatial and temporal variability of the LSL trends. A detailed study of the different forcing factors shows that changes in atmospheric circulation induce LSL trends on the order of 1 mm/yr over five decades, with this forcing most likely being of cyclic nature. Similar orders of magnitude have been found for other regions, too. Postglacial rebound also contributes on the order of 1 to 2 mm/yr, with the largest uncertainty resulting from the uncertain position of peripheral bulge. The contribution from thermal expansion determined from observations appears rather small on the order of a few tenth of mm/yr. Based on results from a regression study by Plag (20060, the contribution from ice sheets was most likely on the order of 0.7 mm/yr. Taking all these contributions, the differences between the sum and the observed LSL trends at the different tide gauges are between -4 mm/yr and 2.5 mm/yr. Thus, there are large uncertainties in explaining the observed LSL trends which mainly come from the postglacial rebound models, the ice sheet contributions, and vertical land motion.