Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rapid Sea Level Rise in the Arctic Ocean May Alter Views of Human Migration

12.10.2006
First marine evidence found of seawater invasion 11,000 years ago

Scientists have found new evidence that the Bering Strait near Alaska flooded into the Arctic Ocean about 11,000 years ago, about 1,000 years earlier than widely believed, closing off the land bridge thought to be the major route for human migration from Asia to the Americas.

Knowledge of climate change and sea level rise in the Arctic Ocean has been limited because sediment cores collected from the floor of the Arctic Ocean have been taken from locations where sediment has accumulated only about one centimeter (less than one-half inch) every 1,000 years. Such slow rates make it impossible for scientists to distinguish between one millennium and the next.

In a paper in the October issue of Geology magazine, lead author Lloyd Keigwin of the Woods Hole Oceanographic Institution (WHOI) and colleagues from WHOI, Neal Driscoll from Scripps Institution of Oceanography at UC San Diego and Julie Brigham-Grette of the University of Massachusetts, Amherst report results from three new core sites north and west of Alaska in the Chukchi Sea. At these locations, accumulation of sediment is more than 100 times greater than at previous sites, allowing identification of climate changes that were previously unseen. During the expeditions, the researchers extracted the longest piston core ever obtained from the Arctic region.

The Chukchi Sea in the Arctic Ocean covers part of the continental shelf exposed when sea level fell during the last glacial maximum, about 20,000 years ago. When sea level was low the climate in the area was more continental across a large area of the Arctic, and when sea level was high the flow of water from the North Pacific Ocean through the Bering Strait between Russia and Alaska, where the sill depth is 50 meters (165 feet), affected the freshwater and nutrient balance of the Arctic and the North Atlantic. The traditional view that humans and fauna migrated across the exposed shelf before flooding has been challenged by recent studies suggesting a maritime route for migration.

“Although we have only a few cores, this is the first evidence of flooding of the Chukchi Sea by 11,000 years ago, at least 1,000 years before previously thought,” Keigwin said. “The new data are also consistent with data from other recent studies, and show potential for developing ocean and climate histories of this region.”

Keigwin, a senior scientist in the WHOI Geology and Geophysics Department, and colleagues surveyed and collected cores from many locations in the Bering and Chukchi Seas in 2002 to study climate and sea level. Cores from these sites reveal that rising sea level flooded the Bering Strait about 12,000 years before present. Since 7,000 years ago, very little sediment has eroded from Alaska compared to before that time, and beginning about 4,000 years ago there has been a decline in biological productivity that may have resulted from increased sea ice or decreased nutrient supply from the Bering Strait.

“Our research suggests there was more ice present in the region during the last glacial period than previously thought,” said co-author Neal Driscoll, a professor in the Geosciences Research Division at Scripps Oceanography. “Evidence of an increased sedimentation rate, along with deep valleys cut into the continental shelf when sea level was rising rapidly during the deglaciation, helped guide us to that result. Additional ice in this region of the Arctic is an important discovery, and is significant in helping our understanding of climate models, circulation and precipitation during glacial periods.”

Cores from Hope Valley on the Chukchi shelf and Barrow Canyon off Point Barrow, Alaska contain high resolution records of climate, sea-level change and the history of the sediment source. The researchers sampled the cores to identify skeletons of animals, known as foraminifera, that can be traced to specific water and atmospheric temperatures. The samples were also radiocarbon dated at the National Ocean Sciences Accelerator Mass Spectrometry facility at WHOI.

The cores were collected during a cruise in 2002 on the U.S. Coast Guard Cutter Healy. The research was funded by the National Science Foundation and the Oak Foundation.

Shelley Dawicki | EurekAlert!
Further information:
http://www.whoi.edu

More articles from Earth Sciences:

nachricht Tiny microenvironments in the ocean hold clues to global nitrogen cycle
23.04.2018 | University of Rochester

nachricht Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

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

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>