Sea levels have risen more than earlier thought, says NASA report

Alphr.com reports, 2nd November 2016: Previous estimates were that global sea levels rose by around 5.5in [14cm] over the 20th century, but researchers from NASA’s Jet Propulsion Laboratory and the University of Hawaii at Manoa now believe that is “highly unlikely,” and the true figure is closer to 6.7in [17cm].

By applying established sea-level estimates to new climate models, the NASA paper discovered that they were some way off the real-world picture.

“It’s not that there’s something wrong with the instruments or the data but, for a variety of reasons, sea level does not change at the same pace everywhere at the same time,” explained Philip Thompson from the University of Hawaii.

These places specifically were 15 gauges set up across America and Europe, but unfortunately they also happened to be the points where sea-level rises were lower than the global average. It may seem a little counter-intuitive, but sea levels rise the most in areas that are further away from the melting ice.

So the gauges were at the right source for melting ice, but the recorded impact wasn’t as severe as spots further away — the southern Pacific Ocean, for example.

On top of this, the researchers also considered the effect of something called “ice melt fingerprints” — sea-level change impacted by changes to the Earth’s rotation and local gravity as large masses of ice melt.

“This is really important, because it provides answers to the question about how melt fingerprints and the influence of wind on ocean circulation affect our ability to estimate past sea-level rise,” said NASA’s Philip Thompson.

“These results suggest that our longest records most likely underestimate past global mean change, and allow us to establish the minimum amount of global sea-level rise that could have occurred during the last century.”

The result is that the impact of the Alps melting has been underestimated by around 5%, while Greenland ice melting has caused sea-level rises around 28% higher than previously thought.
 
Source: Alphr.com, 2nd November 2016. For the full details and graphics, see www.alphr.com/environment/1004673/sea-levels-have-risen-more-than-we-thought-nasa-research-suggests
 
Note: Earlier this year at the Paris Climate Convention it was observed that if climate change proceeds unchecked, then seas could rise by 6 metres worldwide.


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