Sea Level – Bump in the road


NASA reports that the recent decline in sea level is the direct consequence of a shift from El Niño and La Niña in the Pacific.

NASA Bump in the road

The red line in this image shows the long-term increase in global sea level since satellite altimeters began measuring it in the early 1990s. Since then, sea level has risen by a little more than an inch each decade, or about 3 millimeters per year. While most years have recorded a rise in global sea level, the recent drop of nearly a quarter of an inch, or half a centimeter, is attributable to the switch from El Niño to La Niña conditions in the Pacific. The insets show sea level changes in the Pacific Ocean caused by the recent El Niño and La Niña (see http://sealevel/science/elninopdo/ for more information on these images). Image credit: S. Nerem, University of Colorado

Like mercury in a thermometer, ocean waters expand as they warm. This, along with melting glaciers and ice sheets in Greenland and Antarctica, drives sea levels higher over the long term. For the past 18 years, the U.S./French Jason-1, Jason-2 and Topex/Poseidon spacecraft have been monitoring the gradual rise of the world’s ocean in response to global warming.

While the rise of the global ocean has been remarkably steady for most of this time, every once in a while, sea level rise hits a speed bump. This past year, it’s been more like a pothole: between last summer and this one, global sea level actually fell by about a quarter of an inch, or half a centimeter.

So what’s up with the down seas, and what does it mean? Climate scientist Josh Willis of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., says you can blame it on the cycle of El Niño and La Niña in the Pacific.

More (Click here)

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One Response to Sea Level – Bump in the road

  1. Pingback: Sea Levels Much Less Stable Than Earlier Believed, New Coral Dating Method Suggests « Bitter Harvest

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