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 December 22, 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 December 22, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava Inches Closer to Highway

Raw: Lava Inches Closer to Highway

AP (Dec. 21, 2014) Officials have opened a new road on Hawaii's Big Island for drivers to take care of their daily needs if encroaching lava from Kilauea Volcano crosses a highway and cuts them off from the rest of the island. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Raw: Scuba Diving Santa Off Florida Keys

Raw: Scuba Diving Santa Off Florida Keys

AP (Dec. 20, 2014) A scuba diving Santa Claus explored the waters of the Florida Keys National Marine Sanctuary. Dive shop owner Spencer Slate makes the dive each year to help raise money for charity. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
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