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 First global antineutrino emission map highlights Earth's energy budget
01.09.2015 | University of Maryland

nachricht Errant Galileo satellites will be used for research on Einstein’s general theory of relativity
01.09.2015 | Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Increasingly severe disturbances weaken world's temperate forests

Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.

"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...

Im Focus: OU astrophysicist and collaborators find supermassive black holes in quasar nearest Earth

A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.

The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...

Im Focus: What would a tsunami in the Mediterranean look like?

A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).

Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...

Im Focus: Self-healing landscape: landslides after earthquake

In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.

These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...

Im Focus: FIC Proteins Send Bacteria Into Hibernation

Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.

For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking conference in Heidelberg for outstanding mathematicians and computer scientists

20.08.2015 | Event News

Scientists meet in Münster for the world’s largest Chitin und Chitosan Conference

20.08.2015 | Event News

Large agribusiness management strategies

19.08.2015 | Event News

 
Latest News

First global antineutrino emission map highlights Earth's energy budget

01.09.2015 | Earth Sciences

Distant planet's interior chemistry may differ from our own

01.09.2015 | Physics and Astronomy

Magnetic fields provide a new way to communicate wirelessly

01.09.2015 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>