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.
Notes for Editors:The study was published under the following original title:
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:
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
NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center
The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University
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...
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....
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...
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...
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...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences