What is global mean sea level?
This is the average height of the entire ocean surface. Global warming is driving sea levels higher because of two different reasons: water is added when ice sheets and glaciers melt, and seawater expands as it warms.
What are we looking at?
This plot shows global change in sea level since 1992, as observed by satellite altimeters. The black line tracks the measurements, and the width of the blue line shows its accuracy. Data shown are the latest available, with time needed to allow for processing (a lag of up to 4 months). The seasonal ups and downs have also been removed.
Why do we care?
Global mean sea level is an important indicator of how much humans are changing the climate. As sea levels rise, they erode the coastline and threaten coastal communities with increased flooding. Global sea levels are not only rising, the rate of rise is also faster in recent decades.
Reference: Beckley et al., 2017; GMSL dataset