Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study provides first-ever look at combined causes of North Atlantic and Arctic Ocean freshening

28.08.2006
A new analysis of 50 years of changes in freshwater inputs to the Arctic Ocean and North Atlantic may help shed light on what's behind the recently observed freshening of the North Atlantic Ocean.

In a report, published in the August 25, 2006 issue of the journal, Science, MBL (Marine Biological Laboratory) senior scientist Bruce J. Peterson and his colleagues describe a first-of-its-kind effort to create a big-picture view of hydrologic trends in the Arctic. Their analysis reveals that freshwater increases from Arctic Ocean sources appear to be highly linked to a fresher North Atlantic.

"The high-latitude freshwater cycle is one of the most sensitive barometers of the impact of changes in climate and broad-scale atmospheric dynamics because of the polar amplification of the global warming signal," says Peterson. "It's easiest to measure these changes in the Arctic and the better we understand this system, the sooner we will know what is happening to the global hydrologic cycle."

The multi-disciplinary team of scientists led by Peterson calculated annual and cumulative freshwater input anomalies (deviations from expected levels) from net precipitation on the ocean surface, river discharge, net attrition of glaciers, and Arctic Ocean sea ice melt and export for the latter half of the 20th century. The scientists compared the fluxes to measured rates of freshwater accumulation in the North Atlantic during the same time period.

Their analysis showed that increasing river discharge and excess net precipitation on the ocean contributed the most freshwater (~20,000 cubic kilometers) to the Arctic and high-latitude North Atlantic. Sea ice reduction provided another ~15,000 cubic kilometers of freshwater, followed by ~2,000 cubic kilometers from melting glaciers. Together, the sum of anomalous inputs from all of the freshwater sources analyzed matched the amount and rate at which fresh water accumulated in the North Atlantic during much of the period from 1965 through 1995.

"This synthesis allows us to judge which freshwater sources are the largest, but more importantly shows how the significance of different sources have changed over the past decades and what has caused the changes," says Peterson. "It prompts us to realize that the relative importance of different sources will change in future decades. Creating a big-picture or synoptic view of the changes in various components of the high-latitude freshwater cycle puts the parts in a perspective where we can judge their individual and collective impact on ocean freshening and circulation."

In recent years, much attention has been given to the observed freshening of Arctic Ocean and North Atlantic and the potential impacts it may have on the earth's climate. Scientists contend that a significant increase of freshwater flow to the Arctic Ocean could slow or halt the Atlantic Deep Water formation, a driving factor behind the great "conveyor belt" current that is responsible for redistributing salt and thermal energy around the globe, influencing the planet's climate. One of the potential effects of altered global ocean circulation could be a cooling of Northern Europe within this century.

The team's comparison of freshwater sources and ocean sink records revealed that over the last half century changes in freshwater inputs and ocean storage occurred not only in conjunction with one another, but in synchrony with rising air temperatures and an amplifying North Atlantic Oscillation (NAO), a climatic phenomenon that has strong impacts on weather and climate in the North Atlantic region and surrounding continents, and the associated Northern Annular Mode (NAM) index.

Peterson and his colleagues contend that the interplay between the NAO and NAM, and continued rising temperatures from global greenhouse warming, will likely determine whether the Arctic and North Atlantic Oceans will continue to freshen. But the scientists caution that the difficultly in predicting fluctuations in atmospheric circulation makes it impossible to know where we might be headed.

"Atmospheric modes of circulation such as the NAO and NAM exert a great deal of control on net precipitation in the ocean and even on regional temperatures, and hence ice melt as well," says Peterson. "But what drives the NAO is the $64,000 question. Our inability to predict trends in the NAO/NAM means that, even if we could predict global warming very well, a large degree of uncertainty will remain in any forecasts of the decadal-centennial trajectories of the Arctic freshwater balance."

Gina Hebert | EurekAlert!
Further information:
http://www.mbl.edu

More articles from Ecology, The Environment and Conservation:

nachricht When corals eat plastics
24.05.2018 | Justus-Liebig-Universität Gießen

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>