Featured Research

from universities, journals, and other organizations

Ocean currents speed melting of Antarctic ice: A major glacier is undermined from below

Date:
June 27, 2011
Source:
The Earth Institute at Columbia University
Summary:
Stronger ocean currents beneath West Antarctica's Pine Island Glacier Ice Shelf are eroding the ice from below, speeding the melting of the glacier as a whole, according to a new study.

Scientists aboard the Nathaniel B. Palmer visited the Amundsen Sea region in 2009 to study oceanic changes.
Credit: Frank Nitsche, Lamont-Doherty Earth Observatory

Stronger ocean currents beneath West Antarctica's Pine Island Glacier Ice Shelf are eroding the ice from below, speeding the melting of the glacier as a whole, according to a new study in Nature Geoscience. A growing cavity beneath the ice shelf has allowed more warm water to melt the ice, the researchers say -- a process that feeds back into the ongoing rise in global sea levels. The glacier is currently sliding into the sea at a clip of four kilometers (2.5 miles) a year, while its ice shelf is melting at about 80 cubic kilometers a year -- 50 percent faster than it was in the early 1990s -- the paper estimates.

"More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest," said study's lead author, Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory.

In 2009, Jacobs and an international team of scientists sailed to the Amundsen Sea aboard the icebreaking ship Nathaniel B. Palmer to study the region's thinning ice shelves -- floating tongues of ice where landbound glaciers meet the sea. One goal was to study oceanic changes near the Pine Island Glacier Ice Shelf, which they had visited in an earlier expedition, in 1994. The researchers found that in 15 years, melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by 0.2 degrees C or so, that was not enough to account for the jump.

The local geology offered one explanation. On the same cruise, a group led by Adrian Jenkins, a researcher at British Antarctic Survey and study co-author, sent a robot submarine beneath the ice shelf, revealing an underwater ridge. The researchers surmised that the ridge had once slowed the glacier like a giant retaining wall. When the receding glacier detached from the ridge, sometime before the 1970s, the warm deep water gained access to deeper parts of the glacier. Over time, the inner cavity grew, more warm deep water flowed in, more melt water flowed out, and the ice thinned. With less friction between the ice shelf and seafloor, the landbound glacier behind it accelerated its slide into the sea. Other glaciers in the Amundsen region have also thinned or widened, including Thwaites Glacier and the much larger Getz Ice Shelf.

One day, near the southern edge of Pine Island Glacier Ice Shelf, the researchers directly observed the strength of the melting process as they watched frigid, seawater appear to boil on the surface like a kettle on the stove. To Jacobs, it suggested that deep water, buoyed by added fresh glacial melt, was rising to the surface in a process called upwelling. Jacobs had never witnessed upwelling first hand, but colleagues had described something similar in the fjords of Greenland, where summer runoff and melting glacier fronts can also drive buoyant plumes to the sea surface.

In recent decades, researchers have found evidence that Antarctica is getting windier, and this may also help explain the changes in ocean circulation. Stronger circumpolar winds would tend to push sea ice and surface water north, says Jacobs. That in turn, would allow more warm water from the deep ocean to upwell onto the Amundsen Sea's continental shelf and into its ice shelf cavities.

Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches).

The paper adds important and timely insights about oceanic changes in the region, says Eric Rignot, a professor at University of California at Irvine and a senior research scientist at NASA's Jet Propulsion Laboratory. "The main reason the glaciers are thinning in this region, we think, is the presence of warm waters," he said. "Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept."

The study received funding from the US National Science Foundation and the UK National Environment Research Council.


Story Source:

The above story is based on materials provided by The Earth Institute at Columbia University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Stanley S. Jacobs, Adrian Jenkins, Claudia F. Giulivi, Pierre Dutrieux. Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf. Nature Geoscience, 2011; DOI: 10.1038/ngeo1188

Cite This Page:

The Earth Institute at Columbia University. "Ocean currents speed melting of Antarctic ice: A major glacier is undermined from below." ScienceDaily. ScienceDaily, 27 June 2011. <www.sciencedaily.com/releases/2011/06/110626145308.htm>.
The Earth Institute at Columbia University. (2011, June 27). Ocean currents speed melting of Antarctic ice: A major glacier is undermined from below. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2011/06/110626145308.htm
The Earth Institute at Columbia University. "Ocean currents speed melting of Antarctic ice: A major glacier is undermined from below." ScienceDaily. www.sciencedaily.com/releases/2011/06/110626145308.htm (accessed April 17, 2014).

Share This



More Earth & Climate News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com
How Mt. Everest Helped Scientists Research Diabetes

How Mt. Everest Helped Scientists Research Diabetes

Newsy (Apr. 15, 2014) British researchers were able to use Mount Everest's low altitudes to study insulin resistance. They hope to find ways to treat diabetes. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins