Global sea levels rise at rates beyond initial predictions

Posted 28 March 2018

According to a study assessing 25 year’s worth of satellite data, global sea levels are rising at an accelerated rate, which could result in a rise twice as high as previous projections by 2100.

With results published in the journal Proceedings of the National Academy of Sciences (PNAS), researchers looked at altimeter measurements gathered over the last three decades by satellites, such as TOPEX/Poseidon, as well as tide gauge data and climate simulations.

The results revealed that the rate of sea level rise is accelerating by about 0.08 mm per year, which could see the seas rise by at least 10 mm per year by the end of the century.

Lead researcher Steve Nerem told New Atlas that the results are very concerning, considering that estimates made have been conservative.  

“This acceleration, driven mainly by accelerated melting in Greenland and Antarctica, has the potential to double the total sea level rise by 2100 as compared to projections that assume a constant rate – to more than 60 cm instead of about 30 cm," Nerem said. 

"And this is almost certainly a conservative estimate. Our extrapolation assumes that sea level continues to change in the future as it has over the last 25 years. 

“Given the large changes we are seeing in the ice sheets today, that's not likely."

While some of the satellite data is unstable due to fluctuations caused by El Nino and La Nina patterns, the scientists used climate models that determine how much of an effect these events would have. 

"The tide gauge measurements are essential for determining the uncertainty in the [global mean sea level] acceleration estimate," study co-author Gary Mitchum said. 

"They provide the only assessments of the satellite instruments from the ground."

The research team included scientists from the Cooperative Institute for Research in Environmental Sciences, the University of Colorado Boulder, the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University and the National Center for Atmospheric Research.