Relative Sea Level Trends

The sea level trends measured by tide gauges that are presented here are local relative sea level (RSL) trends as opposed to the global sea level trend. Tide gauge measurements are made with respect to a local fixed reference on land. RSL is a combination of the sea level rise and the local vertical land motion. The global sea level trend has been recorded by satellite altimeters since 1992 and the latest global trend can be obtained from NOAA's Laboratory for Satellite Altimetry, with maps of the regional variation in the trend. The University of Colorado's Sea Level Research Group compares global sea level rates calculated by different research organizations and discusses some of the issues involved.

The map above illustrates relative sea level trends , with arrows representing the direction and magnitude of change. Click on an arrow to access additional information about that station.

Relative Sea Level Trends
mm/yr (feet/century)
colored bar in legend Above 9
(Above 3)
colored bar in legend 6 to 9
(2 to 3)
colored bar in legend 3 to 6
(1 to 2)
colored bar in legend >0 to 3
(0 to 1)
colored bar in legend -3 to 0
(-1 to 0)
colored bar in legend -6 to -3
(-2 to -1)
colored bar in legend -9 to -6
(-3 to -2)
colored bar in legend Below -9
(Below -3)

The Center for Operational Oceanographic Products and Services has been measuring sea level for over 150 years, with tide stations of the National Water Level Observation Network operating on all U.S. coasts. Changes in RSL, either a rise or fall, have been computed at 142 long-term water level stations using a minimum span of 30 years of observations at each location. These measurements have been averaged by month which removes the effect of higher frequency phenomena in order to compute an accurate linear sea level trend. The trend analysis has also been extended to 240 global tide stations using data from the Permanent Service for Mean Sea Level (PSMSL). This work is funded in partnership with the NOAA OAR Climate Observation Division.

Frequently Asked Questions:

What is Sea Level?
Why does Sea Level change over time?
What does Sea Level have to do with Climate?
What are the differences between historical and new sea Level trends and confidence intervals?

Data and Resources

Contact Information

For additional information, please contact CO-OPS.