Sleeping glacier may lift seas two metres


A rapidly melting glacier atop East Antarctica is on track to lift oceans at least 2 meters and could soon pass a “tipping point” of no return, researchers said Wednesday.

To date, scientists have mostly worried about the Greenland and West Antarctic ice sheets as dangerous drivers of sea level rise.

But the new study, following up on earlier work by the same team, has identified a third major threat to hundreds of millions of people living in coastal areas around the world.

“I predict that before the end of the century, the great global cities of our planet near the sea will have 2- or 3-meter-high sea defenses all around them,” said Martin Siegert, co-director of the Grantham Institute and Department of Earth Science and Engineering at Imperial College London, and the study’s senior author.

From the air, the contours of Totten Glacier — roughly the size of France — are invisible because the entire Antarctic continent is covered by a seamless, kilometers-thick blanket of snow and ice.

Geologically, however, it is a distinct — and volatile — beast.

Last year, Siegert and colleagues revealed that the underbelly of the glacier — most of which sits below sea level — is being eroded by warm, salty seawater flowing hundreds of kilometers inland after passing through underwater “gateways.

As it does, the portion of the glacier resting on water rather than rock increases, accelerating the pace of disintegration.

The new study, published in Nature, used satellite data to map the hidden geological contours of the region.

The researchers found evidence that Totten similarly melted during an earlier period of natural global warming a few million years ago — a possible dress rehearsal for what is happening today.

“During the Pliocene epoch, temperatures were 2 degrees Celsius (3.6 degrees Fahrenheit) higher than they are right now, and CO2 levels in the atmosphere were 400 ppm,” or parts per million, Siegert said.