Rising seas Sea levels rising more than previously expected

Published 26 February 2018

Studying twenty-five years’ worth of satellite data, scientists paint a grim picture of global warming. Sea levels are going up at a faster rate each year, and even sooner than projected. The calculate that at the current pace, the total sea level rise could be twice as high as previous projections by 2100.

When discussing current predictions on sea level rise, experts all over the world tell us that ocean levels are inevitably on the rise. This much is true. What they do not know is just how fast it is going to be.

So, what is responsible for this worrying development? Levels rise for several reasons. Water expands as it is heated, so it takes up more volume and causes sea levels to rise. This effect is made worse by greenhouse gas emissions. The Greenland and Antarctic ice sheets, the largest bodies of ice in the world, continue to rapidly melt. According to estimates, the Greenland ice sheet has lost about 303 gigatons of mass per year for the last decade. Melting mountain glaciers are also another culprit.

CORDIS says that a new study published in the journal Proceedings of the National Academy of Sciences set out to better understand and predict Earth’s response to a world that keeps getting warmer. The study examined the levels of the world’s oceans by looking at satellite measurements taken since 1992. Data shows that the rate is rising every year.

The research team observed a total rise in the ocean of 7 cm in a quarter century of NASA and European satellite data. It calculated that the sea level is accelerating in recent decades, not rising at a steady rate as previously thought. At this pace, the total sea level rise could be twice as high as previous projections by 2100. They estimated that the rate of sea level rise is accelerating by about 0.08 mm per year. If nothing is done about this, the upward trend could mean the seas would rise by at least 10 mm per year by the end of the century.

“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,” Steve Nerem, lead author and professor of aerospace engineering sciences at the University of Colorado Boulder, told the Independent.

According to Nerem, the total rise between 1993 and 2100 could be 65 cm, and this is a conservative estimate for the rate and acceleration over the next 82 years. “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.”

It is enough to wreak havoc on coastal cities and the many low-lying regions that are at risk of flooding – just think Miami and Shanghai. Are people prepared for rising seas? Those who live in coastal regions or depend on coasts for a living should especially take heed. For them, it is not a question of how much, but rather when. The math does not lie.

— Read more in R. S. Nerem et al., “Climate-change–driven accelerated sea-level rise detected in the altimeter era,” Proceedings of the National Academy of Sciences (9 January 2018) (doi: org/10.1073/pnas.1717312115)