Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Low Arctic Sea Ice Cover in the Summer of 2008

24.09.2008
Climate Scientists' Forecast Confirmed

The Arctic summer nears its end and the minimum extent of sea ice is reached. The Arctic ice cover amounted to 4.5 million square kilometres on September 12th.

This is slightly more than the lowest ice cover ever measured: 4.1 million square kilometres in the year 2007. Scientists are anxious about the development of sea ice because the long-time mean is 2.2 million square kilometres higher.

This development did not come about completely unexpectedly, however. A model calculation conducted at the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association in early summer showed that the ice minimum of the year 2008 would lie below that of the year 2005 with almost one hundred per cent probability. A new minimum below that of the year 2008, however, was expected with a probability of just eight per cent.

"If we regard the sea ice cover from the beginning of satellite observations in the year 1979, the measurement of 2008 comes as a little surprise, because summers with a low ice cover like 2007 are usually followed by winters with a heavy ice production," explains Prof. Rüdiger Gerdes, physical oceanographer at the Alfred Wegener Institute. From 1979 to 2004, about 6 to 7.5 million square kilometres of the Arctic were usually covered with ice. Now it is the second year in a row with less than 4.5 million square kilometres. However, the following summers still have to show if this trend is to continue.

"A hitherto unanswered question is whether the sequence of two extreme years presents a transition towards a new regime of Arctic sea ice, which makes the return to former states of sea ice cover difficult," continues Gerdes. Transitions of this kind show up in coupled climate models. However, they are prognosticated for the late 21st century. The key factor in the model simulations for Arctic sea ice is ice thickness. If the mean thickness falls below a certain threshold value, the main part of sea ice will melt. This means that vast ice-free areas will emerge each summer.

Compared to the extent of ice - which can be measured pretty well by means of satellites - the distribution of ice thickness in the Arctic Ocean is less well-known. The Alfred Wegener Institute contributes to the estimation of the Arctic ice volume and its variability with measurement equipment, which is hauled by helicopters. This way, data from more than fifteen years are at hand and account for a decrease of ice thickness in the central Arctic. However, these measurements do not cover all relevant parts of the Arctic Ocean - the range of the helicopters is too limited. "It cannot be excluded that sea ice is simply mechanically reallocated," reports Gerdes. "Our model computations show that ice transport from eastern to western Arctic waters caused by wind was an important factor in the great ice-free areas of the Siberian Shelf in the year 2007."

RV Polarstern currently benefits from the low sea ice cover in the Arctic Ocean. Scientists on board can measure the seafloor and sample sediment probes in areas, which were unreachable a few years ago. Polarstern cruises through close pack ice with a northerly course in the direction of 80° latitude; however, since it is mostly one year old thin sea ice, it can easily be broken. So far, the participants of the expedition were able to conduct their activities without hindrance.

The Alfred Wegener Institute carries out research in the Arctic and Antarctic as well as in the high and mid latitude oceans. The institute coordinates German polar research and makes available to international science important infrastructure, e.g. the research icebreaker "Polarstern" and research stations in the Arctic and Antarctic. AWI is one of 15 research centres within the Helmholtz Association, Germany's largest scientific organization.

Margarete Pauls | idw
Further information:
http://www.awi.de

Further reports about: Antarctic Arctic Arctic Ocean Arctic sea ice Helmholtz Ocean Polarstern SEA crystalline sea ice

More articles from Earth Sciences:

nachricht New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz

nachricht Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

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....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

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

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>