Featured Research

from universities, journals, and other organizations

Reducing salt is bad for glacial health, NASA finds

Date:
December 6, 2013
Source:
NASA/Jet Propulsion Laboratory
Summary:
A new NASA-led study has discovered an intriguing link between sea ice conditions and the melting rate of Totten Glacier, the glacier in East Antarctica that discharges the most ice into the ocean. The discovery, involving cold, extra salty water -- brine -- that forms within openings in sea ice, adds to our understanding of how ice sheets interact with the ocean, and may improve our ability to forecast and prepare for future sea level rise.

This image shows the Totten Glacier ice shelf in East Antarctica (the wrinkled white area at top left) on Sept. 25, 2013. Two large open-water polynyas appear on the sea ice below and to the right of the shelf, as well as several smaller ones. The open-water areas are bright black. The stippled diagonal line from lower left to upper right is the outer edge of the sea ice, with cloud cover to the right of that line. The image is from the Moderate Resolution Imaging Spectroradiometer instrument on NASA's Aqua satellite.
Credit: NASA

A new NASA-led study has discovered an intriguing link between sea ice conditions and the melting rate of Totten Glacier, the glacier in East Antarctica that discharges the most ice into the ocean. The discovery, involving cold, extra salty water -- brine -- that forms within openings in sea ice, adds to our understanding of how ice sheets interact with the ocean, and may improve our ability to forecast and prepare for future sea level rise.

Related Articles


"I was curious why Totten was changing so fast when the glacier just next to it wasn't changing much," said Ala Khazendar of NASA's Jet Propulsion Laboratory, Pasadena, Calif., lead author of the new study, published online Dec. 5 in the journal Nature Communications. Combining satellite observations with ocean numerical modeling, Khazendar and his colleagues developed a hypothesis that reductions in the volume of brine would increase Totten's thinning and melting. Additional research supported that hypothesis.

Ice loss seen in Antarctica is generally attributed to the well-documented rise in temperature of the surrounding ocean, but scientists are still puzzling out the mechanisms behind the regional variations that they are observing. The new study highlights the key role of processes occurring on small geographic scales in determining how global climate change can affect the stability of ice sheets.

Satellite observations from NASA's ICESat-1, which measures how much ice surfaces are rising or falling over time, revealed that Totten Glacier was thinning rapidly. It currently discharges enough ice into the surrounding ocean to fill Lake Erie in just over a week. The nearby Moscow University Glacier and its floating ice shelf were showing little change. Why the difference? "We were convinced that the answer must be in the ocean," Khazendar said.

The ocean around Antarctica is warmer than both the continent's icy surface and the polar air. Ice shelves (the floating front edges of glaciers that extend tens to hundreds of miles offshore) melt more because of contact with ocean water below them than they do because of sunlight. Melting at the undersides of ice shelves is part of Antarctica's natural water cycle, but when glaciers start melting unusually quickly, it's a sign that something is off balance.

Khazendar and his team of colleagues from JPL; UCLA; the University of California, Irvine; and Utrecht University in the Netherlands combined ICESat remote sensing observations from 2003 to 2008 with ocean numerical computer models to seek insights into the interaction between the ice shelves and their ocean basin.

That ocean basin, as elsewhere around Antarctica, contains polynyas (poe-LEEN-yahs), large, annually recurring openings in the winter sea ice cover. Polynya sizes and numbers vary markedly from winter to winter, although there is no overall trend in this region. The computer simulations revealed that these year-to-year variations in the polynyas greatly affected the glacier's melting rate.

In polynyas, large quantities of sea ice form, only to be swept away by the winds that formed the openings in the first place. When seawater freezes it expels its salts, producing a layer of very dense, briny water at the freezing temperature. The cold and dense brine formed in polynyas sinks to the seafloor, where it can flow into the cavities under the ice shelves, just as warmer ocean water could.

The researchers hypothesized that when the cold brine pooled under Totten Ice Shelf, it mixed with the water there, lowering its temperature and slowing the glacier's winter melt rate. If so, a reduction in cold brine would mean the glacier's winter melt rate would increase.

The team then examined a data set of passive microwave measurements from the Defense Meteorological Satellite Program. These showed that in the latter part of the study period, the extent of polynyas (and therefore the production of cold brine) decreased significantly. ICESat observations showed that at the same time, the thinning of Totten Glacier increased, as the team's hypothesis predicted it would.

If there are more winters with reduced polynya extents, Khazendar points out, the cavity under Totten can fill with warmer ocean water rather than cold brine. "If that happens, the glacier's flow could be significantly destabilized, causing it to discharge even more ice into the ocean," he said.

"With the widespread changes seen in Antarctic sea ice conditions over the last few years, this process could be affecting other glaciers around Antarctica and the volume of ice they discharge into the ocean," he added.

For more information on ICESat, visit: http://icesat.gsfc.nasa.gov/ .For more information on the ECCO2 ocean modeling and data synthesis project, visit: http://ecco2.jpl.nasa.gov/ .


Story Source:

The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Khazendar, M.P. Schodlok, I. Fenty, S.R.M. Ligtenberg, E. Rignot, M.R. van den Broeke. Observed thinning of Totten Glacier is linked to coastal polynya variability. Nature Communications, 2013; 4 DOI: 10.1038/ncomms3857

Cite This Page:

NASA/Jet Propulsion Laboratory. "Reducing salt is bad for glacial health, NASA finds." ScienceDaily. ScienceDaily, 6 December 2013. <www.sciencedaily.com/releases/2013/12/131206143614.htm>.
NASA/Jet Propulsion Laboratory. (2013, December 6). Reducing salt is bad for glacial health, NASA finds. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/2013/12/131206143614.htm
NASA/Jet Propulsion Laboratory. "Reducing salt is bad for glacial health, NASA finds." ScienceDaily. www.sciencedaily.com/releases/2013/12/131206143614.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) — A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) — A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Yellow-Spotted Turtles Rescued from Trafficking

Yellow-Spotted Turtles Rescued from Trafficking

Reuters - Light News Video Online (Nov. 24, 2014) — Hundreds of Amazon River turtles released into the wild in Peru. Sharon Reich reports. Video provided by Reuters
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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