Antarctic ice sheet melting from below, scientists say

The Pine Island Glacier, one of the most rapidly melting ice masses in the world, is being rapidly eaten away by warm currents of water below.

Tim Stanton/NPS
Researchers from the Naval Postgraduate School deployed multiple, unique sensors through 1,640 feet (500 meters) of solid ice to determine how quickly warm water was melting Antarctica's massive Pine Island Glacier from beneath.

A two-month-long expedition to one of the most remote sites on the planet — the sprawling Pine Island Glacier in Antarctica — has revealed that currents of warm water beneath the glacier are melting the ice at a staggering rate of about 2.4 inches (6 centimeters) per day.

An international team of researchers journeyed to the southernmost continent to study the Pine Island Glacier, which is the longest and fastest-changing glacier on the West Antarctic Ice Sheet. This region, in the far reaches of Antarctica, has been of particular interest to scientists because it is among the most rapidly melting ice masses in the world, thinning as it flows to the Amundsen Sea at a rate of about 2.5 miles (4 kilometers) each year.

Since warm seawater flows beneath the ice shelf (the part of the glacier that floats on the ocean), scientists have known that the Pine Island Glacier was melting from below. Now, using sensors deployed across the 31-mile-long (50-km-long) glacier, the researchers have gauged the rate of glacial melt beneath the solid ice. [Album: Stunning Photos of Antarctic Ice]

The results demonstrate the crucial need to better understand melting processes underneath massive glaciers, including how this undersea process will affect global sea-level rise in the future.

"Intensive melting under the Pine Island ice shelf, as observed in our study, could potentially lead to the speed up and ultimate break-up of the ice shelf," David Holland, a professor of mathematics at the Center for Atmosphere Ocean Science at New York University, said in a statement. "That's important, as this ice shelf is currently holding back inland ice, and without that restraining force, the Pine Island catchment basin could further contribute to global sea-level rise."

Glacial plug

The Pine Island Glacier currently acts as a plug that holds back the immense West Antarctic Ice Sheet, whose melting ice contributes to rising sea levels. If the glacier's seaward flow speeds up, there could be global consequences.

As glaciers melt, the water flows down slopes and empties into the ocean, causing sea levels to rise. Warming oceans also cause sea levels to go up, because water expands as its temperature increases. Still, understanding precisely why these changes are occurring, and how much sea levels are projected to rise in the future, is tricky, researchers have said.

Last November, a study published in the journal Science estimated that ice lost from the entire Antarctic ice sheet andGreenland ice sheet is responsible for a fifth of the 2.2 inches (5.59 cm) of sea-level rise observed since 1992.

As the Pine Island Glacier makes its seaward retreat, it also develops and drops icebergs as part of a natural cycle. In early July, a huge iceberg, measuring about 278 square miles (720 square kilometers), broke off from the Pine Island Glacier and floated freely into the Amundsen Sea.

Modeling melt

To see how much the Pine Island Glacier was melting, Holland and his colleagues installed sensors inside holes drilled 1,640 feet (500 m) through the solid ice, at various points across the glacier. The instruments measured ocean temperatures, salinity (or salt content), and the movement of warm-water currents that carve channels through the ice shelf and flow underneath it.

The data, published online today (Sept. 12) in the journal Science, will help scientists piece together how the Pine Island Glacier is changing, and will help them build more accurate models of glacier melt.

"What we have brought to the table are detailed measurements of the melt rates that will allow simple physical models of the melting processes to be plugged into computer models of the coupled ocean/glacier system," Tim Stanton, a research professor at the Naval Postgraduate School, said in a statement. "These improved models are critical to our ability to predict future changes in the ice shelf, and glacier-melt rates of the potentially unstable Western Antarctic Ice Sheet in response to changing ocean forces."

Follow Denise Chow on Twitter @denisechow. Follow LiveScience @livescienceFacebook & Google+. Original article on LiveScience.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to

QR Code to Antarctic ice sheet melting from below, scientists say
Read this article in
QR Code to Subscription page
Start your subscription today