Quantcast
Environmental News for a Healthier Planet and Life

What Would Happen if the Entire West Antarctic Ice Sheet Collapsed?

Popular
What Would Happen if the Entire West Antarctic Ice Sheet Collapsed?
A crack in Antarctica's Pine Island glacier leads to the calving of a major iceberg. Photo credit: NASA Goddard Space Flight Centre / Flickr

By Tim Radford

Scientists in the U.S. have identified an ominous trend in the Southern Ocean—the creation of enormous icebergs as rifts develop in the shelf ice many miles inland.

And although three vast icebergs have broken from the Pine Island glacier in West Antarctica and drifted north in this century alone, researchers have only just worked out what has been going on.

Their first clue came from a telltale shadow in the south polar ice, caught by a NASA satellite and visible only while the sun was low in the sky, casting a long shadow.

It was the first sign of a fracture 20 miles inland, in 2013. Two years later, the rift became complete and the 580 sq km iceberg drifted free of the shelf.

Significant Collapse

"It's generally accepted that it's no longer a question of whether the West Antarctic Ice Sheet will melt—it's a question of when," said study leader Ian Howat, a glaciologist in the School of Earth Sciences at Ohio State University in the U.S.

"This kind of rifting behavior provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes."

The scientists report in Geophysical Research Letters journal says that they discovered that although shelf ice could be expected to wear at the ocean edge, something else was happening in West Antarctica.

The Pine Island glacier is grounded on continental bedrock below sea level, which means that warming ocean water could penetrate far inland beneath the shelf, without anyone being conscious of any change.

The first evidence of something unusual was a valley—the one highlighted by shadows visible only at a particular time and captured by NASA imagery—in the ice, where it had thinned. The valley was the first outward sign that ice was melting far below the surface.

The shelf ice plays an important role in slowing the progress of south polar glaciers: remove the shelf ice and the glacier flow accelerates.

Researchers have already identified evidence of glacier retreat in the West Antarctic and warned that bodies of ice massive enough together to raise global sea levels by three meters could—thanks to global warming as a consequence of fossil fuel combustion—be increasingly unstable.

Calving Icebergs

Dr. Howat said:

The really troubling thing is that there are many of these valleys further up-glacier. If they are actually sites of weakness that are prone to rifting, we could potentially see more accelerated ice loss in Antarctica.

Antarctica is home to more than half the world's fresh water. The Pine Island glacier and its neighbor and twin, the Thwaite glacier, are at the outer edge of an ice stream. In effect, they have "corked" the flow.

But West Antarctica is warming far more swiftly than the rest of the south polar region. And the calving of huge icebergs fuels researchers' fear that, within 100 years, the entire West Antarctic ice sheet could collapse, with disastrous consequences for many coastal cities worldwide.

Reposted with permission from our media associate Climate News Network.

The Gowanus Canal in Brooklyn, New York, a polluted nearly 2 mile-long waterway that is an EPA Superfund site. Jonathan Macagba / Moment / Getty Images

Thousands of Superfund sites exist around the U.S., with toxic substances left open, mismanaged and dumped. Despite the high levels of toxicity at these sites, nearly 21 million people live within a mile of one of them, according to the U.S. Environmental Protection Agency (EPA).

Read More Show Less
EcoWatch Daily Newsletter
The National Weather Service station in Chatham, Massachusetts, near the edge of a cliff at the Monomoy National Wildlife Refuge. Bryce Williams / National Weather Service in Boston / Norton

A weather research station on a bluff overlooking the sea is closing down because of the climate crisis.

Read More Show Less
Trending
Amsterdam is one of the Netherlands' cities which already has "milieuzones," where some types of vehicles are banned. Unsplash / jennieramida

By Douglas Broom

  • If online deliveries continue with fossil-fuel trucks, emissions will increase by a third.
  • So cities in the Netherlands will allow only emission-free delivery vehicles after 2025.
  • The government is giving delivery firms cash help to buy or lease electric vehicles.
  • The bans will save 1 megaton of CO2 every year by 2030.

Cities in the Netherlands want to make their air cleaner by banning fossil fuel delivery vehicles from urban areas from 2025.

Read More Show Less
Protestors stage a demonstration against fracking in California on May 30, 2013 in San Francisco, California. Justin Sullivan / Getty Images

A bill that would have banned fracking in California died in committee Tuesday.

Read More Show Less
EXTREME-PHOTOGRAPHER / E+ / Getty Images

By Brett Wilkins

As world leaders prepare for this November's United Nations Climate Conference in Scotland, a new report from the Cambridge Sustainability Commission reveals that the world's wealthiest 5% were responsible for well over a third of all global emissions growth between 1990 and 2015.

Read More Show Less