Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Look Back and Ahead at Greenland's Changing Climate

07.02.2014
Over the past two decades, ice loss from the Greenland Ice Sheet increased four-fold contributing to one-quarter of global sea level rise. However, the chain of events and physical processes that contributed to it has remained elusive. One likely trigger for the speed up and retreat of glaciers that contributed to this ice loss is ocean warming.

A review paper by physical oceanographers Fiamma Straneo at Woods Hole Oceanographic Institution (WHOI) and Patrick Heimbach at MIT published in Nature explains what scientists have learned from their research on and around Greenland over the past 20 years and describes the measurements and technology needed to continue to move the science forward.


The Greenland Ice Sheet is a 1.7 million-square-kilometer, 2-mile thick layer of ice that covers Greenland. Over the past two decades, ice loss from the Greenland Ice Sheet increased four-fold contributing to one-quarter of global sea level rise. (Photo courtesy of Fiamma Straneo, Woods Hole Oceanographic Institution)

The Greenland Ice Sheet is a 1.7 million-square-kilometer, 2-mile thick layer of ice that covers Greenland. At its edge, glaciers that drain the ice sheet plunge into coastal fjords that are over 600 meters deep – thus exposing the ice sheet edges to contact with the ocean. The waters of the North Atlantic Ocean, which surround southern Greenland, are presently the warmest they have been in the past 100 years. This warming is due to natural climate variability and human induced climate change, and climate models project that it will keep getting warmer. Therefore, it is important to understand if the present ocean warming has contributed to ice loss from the Greenland Ice Sheet and how future warming may result in even more ice loss.

The paper describes the mechanisms causing the melting of the ice sheet, particularly at its margin, where the glaciers extend into the ocean. This so-called “submarine melting” has increased as the ocean and atmosphere have warmed over the past two decades.

“What a lot of research around Greenland and the fjords has shown is that if the North Atlantic Ocean warms, then these warm waters will rapidly reach the fjords and hence the margins of Greenland’s glaciers,” says Straneo.

But scientists today know that the situation is more complex than just “a warmer ocean melts ice.”

A warmer atmosphere is resulting in increased surface melting above the ice sheet, and this runoff too enhances submarine melting. Surface melt water falls through cracks in the glacier creating a freshwater river that rushes out into the ocean at the base of the glacier, sometimes 600 meters (1,800 feet) below sea level. This river mixes rapidly with the dense, salty seawater, contributing to the heat transfer from the ocean to the ice, resulting in even more submarine melting beneath the sea surface.

Straneo describes it as follows: “If you put an ice cube in a glass of water and don’t touch it, it will take a few minutes to melt. But if you stir it, you are making it easier for the warmer water to reach the ice surface, which makes the ice melt faster.”

In a warming climate when both the ocean and atmosphere are warming, Straneo says, “it’s like a double hit on submarine melting. It increases because the ocean is warming, but also because there’s increased surface melt that flows to the ice-ocean boundary and increases submarine melting even more.”

As Greenland continues to lose more ice, it releases more fresh water into the North Atlantic Ocean. Oceanographers are concerned that this increase in fresh water at the surface of the North Atlantic Ocean can act like a cap, preventing the transfer of heat from the ocean to the atmosphere in the conveyor-like ocean circulation system.

Typically, oceanographers have mostly been concerned about anomalous pulses of freshwater that come from the Arctic Ocean. But now, Greenland’s excess fresh water is reaching levels comparable to these Arctic anomalies.

“Greenland will not only affect sea level rise, but it could also start to impact climate by changing the ocean circulation with the addition of so much fresh water in the North Atlantic,” Straneo says.

Due to the lack of hard data from measurements, many questions remain such as how fast will the ice sheet melt and how much mass will be lost.

Although oceanographers like Straneo have been studying the sub-polar North Atlantic for more than 20 years, they began with very little historical data from the ocean around Greenland. The same is true for the ice sheet itself. Prior to the onset of satellites about 20-30 years ago, observations of glaciers are very scarce and scientists have mostly relied on a limited number of historical photos to infer glacial retreat over time.

“Part of what we struggled with, in understanding how the ocean can affect the glaciers, was there were hardly any measurements of ocean conditions near the glaciers before everything started changing,” says Straneo.

Even today, she says: “We have very few measurements where the ice and the ocean meet. Autonomous vehicles might help some and so may moorings deployed through the ice. It’s just that they are expensive and funding is limited.”

That’s why she believes it is important to find more resources and technology that will continue to build a longer historical record of data.

“If we don’t start collecting these measurements for longer periods of time, we’re leaving the same questions that we’re struggling with today for the next generation to answer,” she says.

To begin to address this problem, Straneo and co-author Heimbach are working with other oceanographers, climatologists, and glaciologists to identify a prioritized research agenda for collecting the needed data. Their goal is to build a long enough record that it will help predict how ocean and atmospheric changes will affect Greenland’s glaciers and how those changes in turn impact our climate, she says.

“This is the sort of legacy I would like to leave. Our investment is for the future generation of oceanographers,” she says.

The Woods Hole Oceanographic Institution is a private, independent organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Establisehd 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.

Media Relations | EurekAlert!
Further information:
http://www.whoi.edu

More articles from Earth Sciences:

nachricht Early organic carbon got deep burial in mantle
25.04.2017 | Rice University

nachricht New atlas provides highest-resolution imagery of the Polar Regions seafloor
25.04.2017 | British Antarctic Survey

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>