Understanding Sea Level

Key Indicators

Global Mean Sea Level

This dataset contains the Global Mean Sea Level (GMSL) generated from the Integrated Multi-Mission Ocean Altimeter Data for Climate Research (GMSL dataset). The GMSL is a 1-dimensional time series of globally averaged Sea Surface Height Anomalies (SSHA) from TOPEX/Poseidon, Jason-1, OSTM/Jason-2 and Jason-3. It starts in September 1992 to present, with a lag of up to 4 months. All biases and cross-calibrations have been applied to the data so SSHA are consistent between satellites. Data are reported as changes relative to January 1, 1993 and are 2-month averages. Glacial Isostatic Adjustment (GIA) has been applied. These data are available in ASCII format. Reference: Beckley et al., 2017,

Data shown are latest available, given time needed to allow for processing.


Satellite Altimetry (TOPEX/Poseidon and Jason I, II, III)


Data source: Satellite sea level observations. Credit: GSFC/PO.DAAC
Rate of Change
(± 0.4) mm/yr
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Sea level trends (1993-2016) For over 27 years, satellite altimeters have measured the sea surface height of our ever-changing oceans. This image shows the change in sea surface height across the globe from 1993 to 2019. Credit: NASA

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