Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sea Ice Plays a Pivotal Role in the Arctic Methane Cycle

13.11.2015

Nature study on greenhouse gas feedback mechanisms between the atmosphere, sea ice and ocean

The ice-covered Arctic Ocean is a more important factor concerning the concentration of the greenhouse gas methane in the atmosphere than previously assumed. Experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) report on the newly discovered interactions between the atmosphere, sea ice and the ocean in a recent online study in the journal Nature’s Scientific Reports.


Installation of under-ice sensors during an ice station

Photo: Alfred-Wegener-Institut / S. Hendricks

Sea ice forms a natural barrier on the Central Arctic Ocean, limiting gas exchange between water and atmosphere. Over the past several years, the summer sea ice cover in the Arctic has rapidly decreased. “We’re investigating how the changed conditions are affecting the geochemical interaction between the ocean, ice and atmosphere,” explains Dr Ellen Damm, the first author of the study and a biogeochemist at the Alfred Wegener Institute.

“We were able to confirm that the surface water in the central Arctic contains higher methane concentrations than the atmosphere, which means the Arctic Ocean is a potential source of atmospheric methane. That makes it fundamentally different from oceans in lower latitudes, which – except for a few sporadic sources – are considered methane sinks.”

For the study, Damm and her colleagues from the AWI, the Finnish Meteorological Institute and the University of Bremen analysed geochemical and oceanographic data gathered during a 2011 expedition to the Arctic with the research icebreaker Polarstern. They measured methane levels in both the sea ice and in the water directly below it, and in deeper seawater entirely unaffected by the ice.

“Our study shows that there are previously overlooked feedbacks between ice melting and formation, the atmosphere, and the seawater influenced by ice,” says Damm.

Among other factors, they analysed the salt solution, i.e. the brine, which is constitutes concentrated seawater resulting during the formation of sea ice. They found that the brine had a thousand times higher concentration of methane than the atmosphere – proof that sea ice can be a source of methane.

As a result of the melting and freezing processes, methane in the brine channels can be released into the seawater. Further, the water remains in stable layers, due to the different densities of freshwater and saltwater. As such, the methane from the brine channels remains in the uppermost water layer throughout the summer.

When autumn storms set in and it gets colder, different water layers become mixed (convection), which can release the greenhouse gas into the atmosphere. At that time of year the sea ice cover is fragmented and the “lid” on the ocean has almost disappeared, conditions that are conducive to the release of methane into the atmosphere. The convection-based mixing continues in the winter, and methane continues to escape through the leads between ice floes.

The stable water layers prevent the methane from mixing to greater depths of the Arctic Ocean; the significantly lower methane concentrations (compared to the atmosphere) in the lower layer unaffected by the ice, verify this process. This has two effects: firstly, the newly discovered and as such not previously accounted for near-surface feedback mechanism can lead to the direct release of methane from the sea ice and ocean into the atmosphere.

Secondly, the exchange between atmosphere and the deeper Arctic Ocean is reduced, which also limits the Arctic Ocean’s capacity to act as a methane sink. Co-author and AWI oceanographer Prof Ursula Schauer summarises the study’s importance as follows: “The role of sea ice in gas exchange and gas flux is much more complex than previously assumed, and the processes at work in the Northern Ocean differ greatly from those in lower latitudes. These aspects have to be kept in mind in future climate models.”

Further, she points out, the study raises the question on where the methane originates. Conceivably, methane could be produced in sea ice as it drifts through the Arctic, or methane trapped in sea ice could be transported from other regions.

Original publication:
Ellen Damm, Bert Rudels, Ursula Schauer, Susan Mau and Gerhard Dieckmann: Methane excess in Arctic surface water-triggered by sea ice formation and melting. Nature online: Scientific Reports | 5:16179 | DOI: 10.1038/srep16179

Notes for Editors:

Please find printable images on http://www.awi.de/nc/en/about-us/service/press/press-release/meereis-spielt-eine-wichtige-rolle-im-arktischen-methankreislauf.html. Your contact persons are Dr Ellen Damm (tel. ++49 471 4831-1423; e-mail: Ellen.Damm(at)awi.de) and Dr Folke Mehrtens, Dept. of Communications and Media Relations (tel. ++49 471 4831-2007; e-mail: Folke.Mehrtens(at)awi.de).

The Alfred Wegener Institute conducts research in the Arctic, Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research icebreaker Polarstern and research stations in the Arctic and Antarctic to the national and international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw - Informationsdienst Wissenschaft
Further information:
http://www.awi.de

More articles from Earth Sciences:

nachricht NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center

nachricht The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus 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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>