Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCI and NASA document accelerated glacier melting in West Antarctica

26.10.2016

Study findings will help improve predictions about global sea level rise

Two new studies by researchers at the University of California, Irvine and NASA have found the fastest ongoing rates of glacier retreat ever observed in West Antarctica and offer an unprecedented look at ice melting on the floating undersides of glaciers. The results highlight how the interaction between ocean conditions and the bedrock beneath a glacier can influence the frozen mass, helping scientists better predict future Antarctica ice loss and global sea level rise.


For a pair of recent studies, UCI and NASA JPL scientists examined three neighboring glaciers in West Antarctica that are melting and retreating at different rates. The Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea embayment in West Antarctica, the part of the continent with the largest loss of ice mass.

Credit: NASA JPL

The studies examined three neighboring glaciers that are melting and retreating at different rates. The Smith, Pope and Kohler glaciers flow into the Dotson and Crosson ice shelves in the Amundsen Sea embayment in West Antarctica, the part of the continent with the largest decline in ice.

"Our primary question is how the Amundsen Sea sector of West Antarctica will contribute to sea level rise in the future, particularly following our observations of massive changes in the area over the last two decades," said UCI's Bernd Scheuchl, lead author on the first of the two studies, published in the journal Geophysical Research Letters in August.

"Using satellite data, we continue to measure the evolution of the grounding line of these glaciers, which helps us determine their stability and how much mass the glacier is gaining or losing," said the Earth system scientist. "Our results show that the observed glaciers continue to lose mass and thus contribute to global sea level rise."

Scheuchl's team compared radar measurements from the European Space Agency's Sentinel-1 mission and data from the earlier ERS-1 and ERS-2 satellites to identify changes in each glacier's grounding line -- the boundary where it loses contact with bedrock and begins to float on the ocean.

The grounding line is important because nearly all glacier melting takes place on the underside of this floating portion, called the ice shelf. If a glacier loses mass from enhanced melting, it may start floating farther inland from its former grounding line, just as a boat stuck on a sandbar may be able to float again if a heavy cargo is removed. This is called grounding line retreat.

UCI and NASA researchers found that the Smith Glacier's grounding line had retreated 1.24 miles (2 kilometers) per year since 1996. The Pope Glacier's grounding line receded more slowly, at 0.31 miles (0.5 kilometers) annually since 1996. And the Kohler Glacier's grounding line, which had gradually retreated, actually readvanced 1.24 miles (2 kilometers) since 2011.

Scheuchl credits the Sentinel-1 radar mission with changing the way scientists look at polar ice sheets. "It's a two-satellite constellation with funding for more than 20 years, and Europe is committing resources for regular ice sheet data acquisitions," he said. "Our work shows that the data collected is very well-suited for ice sheet science, and we can combine it with other satellite and airborne data sets to establish a more detailed record of these glaciers."

For a separate study, the NASA Jet Propulsion Laboratory's Ala Khazendar -- a co-author of Scheuchl's paper -- measured ice loss at the bottom of the three glaciers, which he suspected might be influencing the changes in their grounding lines. His work, published today in the journal Nature Communications, involved gauging the thickness and height of the ice via radar and laser altimetry instruments utilized in NASA's Operation IceBridge and earlier NASA airborne campaigns.

Radar waves penetrate glaciers all the way to their base, allowing direct assessment of how the bottom profiles of the three glaciers at their grounding lines differed between 2002 and 2014. Laser measurements of surface elevation were used to infer changes in the thickness of the floating ice shelves.

Previous studies using other techniques estimated the average melting rates at the bottom of the Dotson and Crosson ice shelves to be about 40 feet (12 meters) per year. Khazendar and his team, analyzing their direct radar measurements, found stunning rates of ice loss from the glaciers' undersides on the ocean sides of their grounding lines. The fastest-melting glacier, Smith, lost between 984 and 1,607 feet (300 and 490 meters) in thickness between 2002 and 2009 near its grounding line, or up to 230 feet (70 meters) per year.

Those years encompass a period when rapid mass loss was seen around the Amundsen Sea. The regional scale of the decline made scientists strongly suspect that an increase in the influx of ocean heat beneath the ice shelves must have taken place. "Our observations provide a crucial piece of evidence to support that suspicion, as they directly reveal the intensity of ice melting at the bottom of the glaciers during that period," Khazendar said.

"If I had been using data from only one instrument, I wouldn't have believed what I was looking at, because the thinning was so large," he added. However, the two IceBridge instruments, which employ different techniques, both measured the same rapid ice loss.

Khazendar said Smith's fast retreat and thinning are likely related to the shape of the underlying bedrock over which it was retreating between 1996 and 2014, which sloped downward toward the continental interior, and oceanic conditions in the cavity beneath the glacier. As the grounding line receded, warm and dense ocean water could reach the newly uncovered deeper parts of this cavity, causing more melting.

As a result, Khazendar said, "more sections of the glacier become thinner and float, meaning that the grounding line continues retreating, and so on." Smith's retreat might slow down now that its grounding line has reached bedrock that rises farther inland of the 2014 grounding line. Pope and Kohler, in contrast, are on bedrock that slopes upward toward the interior.

The question remains whether other glaciers in West Antarctica will behave more like Smith or more like Pope and Kohler. Many glaciers in this sector of Antarctica are on beds that deepen farther inland, like Smith's. However, Khazendar and Scheuchl said, researchers need more information on the shape of the bedrock and seafloor beneath the ice, as well as more data on ocean circulation and temperatures, to be able to better project how much ice these glaciers will contribute to the ocean in a changing climate.

###

Scheuchl's co-authors on the Geophysical Research Letters study are JPL's Khazendar and Jeremie Mouginot, Mathieu Morlighem and Eric Rignot from UCI's Department of Earth System Science.

Khazendar's co-authors on the Nature Communications study are UCI's Mouginot, Rignot, Scheuchl and Isabella Velicogna, along with Dustin Schroeder, Helene Seroussi, Michael Schodlok and Tyler Sutterley of JPL.

About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 30,000 students and offers 192 degree programs. It's located in one of the world's safest and most economically vibrant communities and is Orange County's second-largest employer, contributing $5 billion annually to the local economy. For more on UCI, visit http://www.uci.edu.

Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.

NOTE TO EDITORS, IMAGE AVAILABLE AT:

https://news.uci.edu/research/uci-and-nasa-document-accelerated-glacier-melting-in-west-antarctica/

Contact:

Brian Bell
UCI
949-824-8249
bpbell@uci.edu

Alan Buis
JPL
818-354-0474
alan.buis@jpl.nasa.gov

http://www.uci.edu 

Brian Bell, UCI | EurekAlert!

Further reports about: Amundsen Sea Antarctica GLACIERS NASA UCI West Antarctica ice loss ice shelves sea level rise

More articles from Earth Sciences:

nachricht Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland
15.11.2018 | Faculty of Science - University of Copenhagen

nachricht The unintended consequences of dams and reservoirs
14.11.2018 | Uppsala University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>