Antarctica’s Ice Shelves Are Vanishing, and That Could Mean Higher Sea-Level Rise
The supersize cliffs of ice extending off the Antarctic coast help control the height of the sea worldwide. For centuries, if not millennia, this icy barrier has slowed the flow of the southern continent’s massive freshwater glaciers into the ocean.
But the ice shelves themselves are melting at a troubling rate, scientists revealed on Thursday, as warming ocean waters dissolve them faster from the underside up. The results may increase sea levels beyond what’s already expected along the world’s coastlines, where the majority of the human population is concentrated, over the next several decades.
That in turn could intensify the damage, injuries or deaths, and dislocations of communities from extreme coastal storms and flooding.
In a study published in the journal Science, a team of U.S. researchers grouped and analyzed 18 years of satellite data on the thickness of Antarctica’s ice shelves. They found that the ice shelves went from losing a modest 16 square miles of ice a year from 1994 to 2003, to losing about 193 square miles of ice a year from 2003 to 2012.
Along the West Antarctic coast, ice shelves in the Amundsen and Bellinghausen seas lost 18 percent—or nearly one-fifth—of their volume in less than 10 years, and the rate of melting rose by 70 percent over roughly the same time period.
The trend is less clear for East Antarctica, the researchers found, compared with the unequivocal thinning ice along the continent’s western edge. They believe more data over time are needed to better understand what’s happening.
If West Antarctic ice shelves melt at a faster rate than snowfall is adding to the continent’s inland glaciers, there will be too little mass along the coastline to hold back the West Antarctic Ice Sheet as it flows into the ocean. That in turn would mean more glacier ice entering the sea and melting in future decades than in the past.
The increased amount of freshwater coming into the global ocean could raise sea levels up to 28 inches by 2100, on top of what’s already anticipated, Paul Holland of the British Antarctic Survey told The Guardian.