Wednesday, September 9, 2015

Tracking Changes in Sea Level over the Past Two Decades

http://www.accuweather.com/en/weather-blogs/climatechange/tracking-changes-in-sea-level/52270678

Globally, there has been an average increase in sea level of 6 centimeters since the 1993, according to NASA's Josh Willis of the Jason-3 mission. However, the rate of increase or decrease is not not the same everywhere.
Over 90 percent of the heat trapped by greenhouse gases is absorbed by the oceans. This increase in heat causes the water to expand (thermal expansion), which is one driver of sea level rise. The other driver is the melting of glaciers and ice sheets across the polar regions.
Using data from TOPEX/Poseidon, Jason-1 and Jason-2, NASA was able to put together an animated graphic of the world showing how sea-levels have changed since 1993. The red/orange areas indicate a regions where the sea level is rising, white areas indicate little change while the blue areas show sea level fall. Clearly, much of the planet in in the red and orange.
One reason for a decrease in sea level in some areas of the Pacific has to do with the 15-30 year cycle of the Pacific Decadal Oscillation, according to Willis.
The blue areas in the western Atlantic could be indicative of a slight northward shift of the Gulf Stream.

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