Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Understanding the Ocean's Role in Greenland Glacier Melt

24.06.2014

The Greenland Ice Sheet is a 1.7 million-square-kilometer, 2-mile thick layer of ice that covers Greenland. Its fate is inextricably linked to our global climate system.

In the last 40 years, ice loss from the Greenland Ice Sheet increased four-fold contributing to one-quarter of global sea level rise.  Some of the increased melting at the surface of the ice sheet is due to a warmer atmosphere, but the ocean’s role in driving ice loss largely remains a mystery.


Icebergs in Sermilik Fjord, near the terminus of Helheim Glacier, in August 2013.

(Photo credit: Magdalena Andres)

Research by scientists at Woods Hole Oceanographic Institution (WHOI) and the Univ. of Oregon sheds new light on the connection between the ocean and Greenland’s outlet glaciers, and provides important data for future estimates of how fast the ice sheet will melt and how much mass will be lost. The study was published today in Nature Geosciences.

“Over the past few decades, many glaciers that drain the Greenland Ice Sheet have accelerated, thinned and retreated,” said the study’s lead author, Rebecca Jackson, a graduate student in the MIT-WHOI joint program in oceanography.

“Scientists have noticed a link between glacier behavior and warming waters off the coast of Greenland, but we have very few direct measurements of ocean waters near the glaciers or at what time scales they vary, which are needed to understand what’s happening there.”

Currently, scientists think that the accelerated rate of ice sheet melt might be due to warmer ocean waters melting on the underside of the ice, where the glaciers extend into the ocean. Little, however, is known about this “submarine melting” – it has not been directly measured at any of Greenland’s major outlet glaciers, and scientists have limited information about the ocean temperature or circulation near the glaciers, which, they think, will impact the melt rate.

To begin to tease apart the mechanisms in this dynamic system, scientists needed more data.

Between 2009 and 2013, the study’s co-authors –Jackson, WHOI physical oceanographer Fiamma Straneo and David Sutherland from University of Oregon – deployed multiple moorings in two fjords where the third and fifth largest outlet glaciers of the Greenland Ice Sheet terminate.  In one study site, moorings were located in the middle of the fjord, in the upper fjord toward the glacier, and on the shelf outside the fjord.

At the second study site, a cluster of moorings were deployed in the middle of the second fjord. The moorings collected extensive measurements of temperature and salinity at various water depths, with some measured ocean currents -- the first data to provide information about the fjords’s conditions from fall through the spring. 

“Almost all previous studies of Greenland’s fjords were conducted during the summer when the waters are fairly calm, and were relatively brief –  with no information about how fast water properties change or what drives those changes,” Jackson noted.

From their analysis of the data, the researchers found rapid fluctuations in ocean temperature near the glaciers, resulting from “surprisingly” fast ocean currents in the fjords. The fjord currents, which reverse every few days, are driven by winds and ocean currents outside the fjord. These findings imply that changes in temperature in the ocean waters outside the fjord can be rapidly communicated to the glacier, through an efficient pumping of new water into the fjord.

“We see much more variability in the upper fjord than we would have expected,” Jackson said. “Our findings go against the prevailing paradigm that focused on the input of freshwater to the fjord as a driver of new water into the fjord.”

Furthermore, the observed variability in ocean properties near the glaciers suggests large and rapid fluctuations in submarine melt rates.  The scientists suspect the melt rate of the glacier varies with the temperature of the water near the glacier.

“These observations of ocean conditions near outlet glaciers are one step towards a better understanding of submarine melting and the impact of the ocean on the Greenland Ice Sheet,” Jackson said.

The research was funded by the National Science Foundation and the WHOI Ocean Climate Change Institute.

The Woods Hole Oceanographic Institution is a private, independent organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. For more information, please visit www.whoi.edu

Media Relations Office | Eurek Alert!
Further information:
http://www.whoi.edu/news-release/greenland-ocean-temp

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>