How fast are sea levels actually rising?

The answer

Global mean sea level has risen approximately 21 to 24 centimeters since 1880, with the rate accelerating significantly in recent decades. From 1993 to 2023, satellite altimetry measured a rise of about 3.4 millimeters per year, more than double the average rate of 1.5 millimeters per year observed over the 20th century. The primary drivers are thermal expansion of warming seawater and meltwater from glaciers and ice sheets. Current projections suggest a further rise of 0.3 to 1.0 meter by 2100 depending on emission scenarios, threatening hundreds of millions of coastal residents.