Global sea-level rise has accelerated over the last decade, contrary to previous estimates, reports a paper published online in Nature Climate Change. Past studies of satellite data, which did not take vertical land movement (VLM) into account when calculating sea levels, showed a slowing in sea-level rise during the same period.
Christopher Watson and colleagues now use GPS measurements of VLM, in combination with hourly data from a network of tide gauges distributed across the world’s oceans, to identify and correct inaccuracies in satellite measurements of sea level. They find that the overall rate of global mean sea-level rise is reduced, from 3.2 mm per year to 2.6-2.9 mm per year, between 1993 and mid-2014.
The first 6 years of the record (1993-1999) are most affected by these corrections, requiring a scaling down of estimates by 0.9-1.5 mm per year. This recalculation means that the rate of rise has actually accelerated in recent years compared with the twentieth century. The authors suggest that this acceleration is in reasonable agreement with the contribution of melting from the Greenland and West Antarctic ice sheets over this period, and is also in line with recent model projections.