Satellite altimetry has shown that global mean sea level has been rising at a rate of ∼3 ± 0.4 mm/y since 1993. Using the altimeter record coupled with careful consideration of interannual and decadal variability as well as potential instrument errors, we show that this rate is accelerating at 0.084 ± 0.025 mm/y2, which agrees well with climate model projections. If sea level continues to change at this rate and acceleration, sea-level rise by 2100 (∼65 cm) will be more than double the amount if the rate was constant at 3 mm/y.

Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era.