Sea Level Rise Is Accelerating: What the Data Shows

Global mean sea level has risen approximately 21 cm since 1880, with the rate accelerating from 1.4 mm/year in the 20th century to 3.6 mm/year today according to satellite altimetry. NASA satellite data shows that the rate of rise has doubled since 1993. Thermal expansion of warming ocean water accounts for about one-third of the increase, while melting glaciers and ice sheets contribute the remaining two-thirds. The Greenland ice sheet alone lost an average of 270 billion tons of ice per year between 2016 and 2020.

Antarctica contributes another 150 billion tons annually. Projections for 2100 range from 30 cm under aggressive emissions cuts to over 1 meter under business-as-usual scenarios. Some studies incorporating ice-sheet instability mechanisms suggest 2 meters is possible. NOAA maintains a network of over 200 tide gauges along US coastlines that track relative sea level change, which varies by location due to land subsidence or uplift.

The Gulf Coast experiences some of the fastest relative rise in the world at 10+ mm/year in parts of Louisiana, where sediment compaction and fossil fuel extraction compound the global trend..