Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Traces of immense prehistoric ice sheets

01.10.2013
The climate history of the Arctic Ocean needs to be rewritten

Geologists and geophysicists of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), discovered traces of large ice sheets from the Pleistocene on a seamount off the north-eastern coast of Russia.


Map of the Arctic, including the location of the ancient ice sheet.
Map: Frank Niessen/IBCAO, Jakobsson et al. Geophysical Research Letters, doi: 10.1029/2012GL052219.


Bathymetric map of the Arlis Plateau with sets of different streamlined glacial lineations. The arrow marks the flow direction of the ancient ice sheets.
Map: Frank Niessen, Alfred-Wegener-Institut

These marks confirm for the first time that within the past 800,000 years in the course of ice ages, ice sheets more than a kilometre thick also formed in the Arctic Ocean. The climate history for this part of the Arctic now needs to be rewritten, report the AWI scientists jointly with their South Korean colleagues in the title story of the current issue of the scientific journal Nature Geoscience.

AWI geologist Dr. Frank Niessen and colleagues had already discovered the first signs of conspicuous scour marks and sediment deposits on the ocean floor north of Wrangle Island (Russia) on a Polarstern expedition in 2008. However, they were unable to gather extensive proof until last year, during an Arctic expedition on the South Korean research vessel Araon. "After we had analysed the bathymetric and seismic data from our first voyage, we knew exactly where we needed to search and survey the ocean floor with the swath sonar of the Araon on the second expedition," said Frank Niessen, the first author of the study.

The result of this research is a topographic map of the Arlis Plateau, a seamount on which deep, parallel-running furrows can be discerned on the upper plateau and the sides – and over an area of 2500 square kilometres and to an ocean depth of 1200 metres. "We knew of such scour marks from places like the Antarctic and Greenland. They arise when large ice sheets become grounded on the ocean floor and then scrape over the ground like a plane with dozens of blades as they flow. The remarkable feature of our new map is that it indicates very accurately right off that there were four or more generations of ice masses, which in the past 800,000 years moved from the East Siberian Sea in a north-easterly direction far into the deep Artic Ocean," says Frank Niessen.

These new findings overturn the traditional textbook view of the history of Arctic glaciations. “Previously, many scientists were convinced that mega-glaciations always took place on the continents – a fact that has also been proven for Greenland, North America, and Scandinavia. However, it was assumed that the continental shelf region of North-eastern Siberia became exposed in these ice ages and turned into a vast polar desert in which there was not enough snow to enable a thick ice shield to form over the years. Our work now shows that the opposite was true. With the exception of the last ice age 21,000 years ago, ice sheets formed repeatedly in the shallow areas of the Arctic Ocean. These sheets were at least 1200 metres thick and presumably covered an area as large as Scandinavia," says Frank Niessen.

The AWI scientists still cannot say for certain, however, under what climate conditions these ice sheets formed and when exactly they left their marks on the bottom of the Arctic Ocean. "We theorize that the East Siberian ice sheets arose during various ice ages when the average global temperature was around five to eight degrees Celsius cooler than what it is today. But evidently this relatively minor temperature difference was often sufficient to allow initially thin ocean ice to grow into an immense ice cap. An example that shows just how sensitively the Arctic reacts to changes in the global climate system," says the geologist.

In a next step, the AWI researchers now want to try collecting soil samples from deeper layers of the ocean floor with a sediment core drill and thus learn more details about the prehistoric ice sheets. "Our long-term goal is to reconstruct the exact chronology of the glaciations so that with the aid of the known temperature and ice data, the ice sheets can be modelled. On the basis of the models, we then hope to learn what climate conditions prevailed in Eastern Siberia during the ice ages and how, for example, the moisture distribution in the region evolved during the ice ages," says Frank Niessen. This knowledge should then help predict possible changes in the Arctic as a consequence of climate change more accurately.

Frank Niessen and his colleagues are anticipating a great number of surprising discoveries in the Arctic Ocean in the future.

"As the Arctic Ocean sea-ice cover continues to shrink, more formerly unexplored ocean area becomes accessible. Today less than ten percent of the Arctic Ocean floor has been surveyed as thoroughly as the Arlis Plateau," says the AWI geologist. And this study would not have succeeded were it not for the outstanding cooperation of the AWI scientists with researchers of the South Korean Polar Research Institute KOPRI. "We complemented each other perfectly in this research. Our South Korean colleagues had the expedition and ship time, we knew the coordinates of the area in which we now found the evidence of the mega-glaciations," says Frank Niessen.

Glossary:

Ice ages:
About 2.7 million years ago the global climate cooled considerably. We have had a permanent ice cap on Greenland ever since. Then came around 55 changes between ice ages and warm periods until today. About 800,000 years ago the magnitude and duration of the glaciations in the Northern Hemisphere increased considerably. Since then the world climate has regularly alternated between two extremes: each cycle of an ice age followed by a warm period now lasts 100,000 years. Warm periods or interglacials, such as the "Holocene” in which we are living, only lasted about 10,000 to 15,000 years. Afterwards the ice masses on the continents began to grow once again, causing the sea level to drop as much as 130 metres compared to today at the peaks of the glacial cycles. Vast areas of the northern continents were then covered by kilometre-thick ice masses, which, for example, expanded over and over again from Scandinavia even into Northern Germany. The last time that this happened was 21,000 years ago. Thus far there has been little research on the role of the Arctic Ocean in this interplay.

Notes for Editors:

The study was published under the following original title:
Frank Niessen, Jong Kuk Hong, Anne Hegewald, Jens Matthiessen, Rüdiger Stein, Hyoungjun Kim, Sookwan Kim, Laura Jensen,Wilfried Jokat, Seung-Il Nam and Sung-Ho Kang: Repeated Pleistocene glaciation of the East Siberian continental margin, Nature Geoscience, October 2013, DOI: 10.1038/NGEO1904; link to online version: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1904.html

Please find printable images and maps under http://www.awi.de/en/news/press_releases/.

Your scientific contact person at the Alfred Wegener Institute is:
Dr. Frank Niessen (Tel.: +49 471 4831-1216, mobile: 0172-409 55 69, e-mail: Frank.Niessen(at)awi.de)

Your contact person in the Department of Communications and Media Relations is Sina Löschke, (Tel.: +49 471 4831-2008, e-mail: medien(at)awi.de).

Follow the Alfred Wegener Institute on Twitter (https://twitter.com/#!/AWI_de) and Facebook (http://www.facebook.com/AlfredWegenerInstitut) to obtain all current news and information on everyday stories from the life of the Institute.

The Alfred Wegener Institute conducts research in the Arctic and 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 stations in the Arctic and Antarctic to the 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
Further information:
http://www.awi.de/en/news/press_releases/

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>