Sea level rise is accelerating: Study

Erosion eats away at the tip of the Uppards in an area called Canaan in Tangier, Virginia, where climate change and rising sea levels threaten the inhabitants of the slowly sinking island. (Jim Watson, AFP)
Erosion eats away at the tip of the Uppards in an area called Canaan in Tangier, Virginia, where climate change and rising sea levels threaten the inhabitants of the slowly sinking island. (Jim Watson, AFP)

Miami – Sea level rise is accelerating and could reach 66cm by century's end, in line with United Nations estimates and enough to cause significant problems for coastal cities, a study said on Monday.

The past annual rate of sea level rise – about 3mm per year – may more than triple to 10mm per year by 2100, said the report in the Proceedings of the National Academy of Sciences (PNAS), a peer-reviewed US journal.

The findings are "roughly in agreement with the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5) model projections," said the report, based on 25 years of satellite data.

"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 60cm instead of about 30," said study author Steve Nerem.

"And this is almost certainly a conservative estimate," added Nerem, a professor of aerospace engineering sciences at the University of Colorado Boulder.

'Thermal expansion'

Co-authors on the study came from the University of South Florida, NASA Goddard Space Flight Centre, Old Dominion University and the National Centre for Atmospheric Research.

Climate change leads to rising seas in two ways.

For one, higher concentrations of greenhouse gases in the atmosphere boost the temperature of water and warm water expands.

This so-called "thermal expansion" of the oceans has already contributed about half of the 7cm of average global sea level rise in the past quarter century, Nerem said.

Oceans also rise with the increasing flow of water due to rapidly melting ice at the poles.

"This study highlights the important role that can be played by satellite records in validating climate model projections," said co-author John Fasullo, a climate scientist at the National Centre for Atmospheric Research.

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