For over 20 years, satellite altimeters have measured the sea surface height of our ever-changing oceans. This series of images shows the complicated patterns of rising and falling ocean levels across the globe from 1993 to 2015. Sea levels reflect changing currents (which tilt the sea surface), the redistribution of heat (which makes sea levels higher) and the long term rise in global sea levels that is the result of human-caused warming. The globally averaged rise is traced out in the bottom right-hand corner. These maps are made using data from at least two satellites at all times, and colors represent highs and lows between 30 cm of normal levels. Toward the end, the expansion of last year's record-breaking El Niño can be seen in the tropical eastern Pacific. The grids and figures were produced at the Jet Propulsion Laboratory (JPL), California Institute of Technology, under the NASA MEaSUREs program (version JPL 1603). [Credit: NASA/JPL-Caltech].
Monday, December 5, 2016