- The rate of global mean sea level rise has accelerated during the last two centuries. Tide gauges show that global mean sea level rose at a rate of around 1.7 mm/year over the 20th century, but there have been significant decadal variations around this value.
- Satellite measurements show a rate of global mean sea-level rise of around 3.2 mm/year over the last two decades.
- Global mean sea level rise during the 21st century will likely occur at a higher rate than during 1971–2010. Process-based models project a rise in 2081–2100, compared to 1986–2005, that is likely to be in the range 0.26–0.54 m for a low emissions scenario (RCP2.6) and 0.45–0.81 m for a high emissions scenario (RCP8.5). There is low confidence in the projections of semi-empirical models, which project a rise up to twice as large as the process-based models.
- Available process-based models indicate global mean sea level rise by 2300 to be less than 1 m for greenhouse gas concentrations that peak and decline and do not exceed 500 ppm CO2-equivalent but 1–3 m for concentrations above 700 ppm CO2-equivalent.
- Absolute sea level is not rising uniformly at all locations, with some locations experiencing much greater than average rise. Coastal impacts also depend on the vertical movement of the land, which can either add to or subtract from climate-induced sea-level change, depending on the particular location.