This indicator describes how sea level has changed over time. The indicator describes two types of sea level changes: absolute and relative.
This indicator presents trends in sea level based on measurements from tide gauges and from satellites that orbit the Earth. Tide gauges measure relative sea level change at points along the coast, while satellite instruments measure absolute sea level change over nearly the entire ocean surface. Many tide gauges have collected data for more than 100 years, while satellites have collected data since the early 1990s.
Figure 1 shows annual absolute sea level change averaged over the entire Earth’s ocean surface. The long-term trend is based on tide gauge data that have been adjusted to show absolute global trends through calibration with recent satellite data. This long-term data set has been calculated through 2013, while satellite data are now available through the end of 2015. Figure 2 shows trends at a more local scale, highlighting the 1960 to 2015 change in relative sea level at 67 tide gauges along the Atlantic, Pacific, and Gulf coasts of the United States.