West Antarctic ice sheet faces ‘unavoidable’ melting, a warning for sea level rise - the Washington Post

That is expected to cause “widespread increases in ice-shelf melting, including in regions crucial for ice-sheet stability,” according to a study published in the journal Nature Climate Change on Monday. Unlike relatively thin and floating sea ice, the ice shelves are thicker and hold back massive glaciers that contain far more ice.

“It appears we may have lost control of the West Antarctic ice shelf melting over the 21st century,” Kaitlin Naughten, the study’s lead author and an ocean modeler with the British Antarctic Survey, told reporters in a media briefing. “That very likely means some amount of sea level rise that we cannot avoid.

The research helps to solidify an understanding that humans have probably already pushed some polar ice systems past a tipping point and into escalating decline.

Arctic sea ice has been decreasing for decades, with data suggesting an “irreversible” thinning around the North Pole since 2007. And while Antarctic sea ice has been more stable, it now may be showing signs of dramatic declines as well. Sea ice cover hit a record low around the South Pole in February and last month reached a winter maximum that was its smallest ever observed, by a wide margin.

As the Southern Ocean warms, thinning the floating sea ice, it also increasingly threatens the ice shelves. The new research underscores what dozens of studies have suggested for three decades, said glaciology researcher Ted Scambos: The West Antarctic ice sheet appears to be headed for an eventual “collapse.”

“It is the opposite of resilient,” Scambos, a senior research scientist at the Earth Science & Observation Center at the University of Colorado at Boulder, said in an email. “It takes an ice age to build it, but in a warm period, like now, it teeters on instability…”