The increasing rate of global mean sea-level rise during 1993-2014

Global mean sea level (GMSL) has been rising at a faster rate during the satellite altimetry period (1993-2014) than previous decades, and is expected to accelerate further over the coming century. However, the accelerations observed over century and longer periods have not been clearly detected in altimeter data spanning the past two decades. Here we show that the rise, from the sum of all observed contributions to GMSL, increases from 2.2 ± 0.3 mm yr^-1 in 1993 to 3.3 ± 0.3 mm yr^-1 in 2014. This is in approximate agreement with observed increase in GMSL rise, 2.4 ± 0.2 mm yr^-1 (1993) to 2.9 ± 0.3 mm yr^-1 (2014), from satellite observations that have been adjusted for small systematic drift, particularly affecting the first decade of satellite observations. The mass contributions to GMSL increase from about 50% in 1993 to 70% in 2014 with the largest, and statistically significant, increase coming from the contribution from the Greenland ice sheet, which is less than 5% of the GMSL rate during 1993 but more than 25% during 2014. The suggested acceleration and improved closure of the sea-level budget highlights the importance and urgency of mitigating climate change and formulating coastal adaption plans to mitigate the impacts of ongoing sea-level rise.