Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sediment yields climate record for past half-million years

18.06.2009
Researchers here have used sediment from the deep ocean bottom to reconstruct a record of ancient climate that dates back more than the last half-million years.
The record, trapped within the top 20 meters (65.6 feet) of a 400-meter (1,312-foot) sediment core drilled in 2005 in the North Atlantic Ocean by the Integrated Ocean Drilling Program, gives new information about the four glacial cycles that occurred during that period.

The new research was presented today at the Chapman Conference on Abrupt Climate Change at Ohio State University’s Byrd Polar Research Center. The meeting is jointly sponsored by the American Geophysical Union and the National Science Foundation.

Harunur Rashid, a post-doctoral fellow at the Byrd Center, explained that experts have been trying to capture a longer climate record for this part of the ocean for nearly a half-century. “We’ve now generated a climate record from this core that has a very high temporal resolution, one that is decipherable at increments of 100 to 300 years,” he said.

While climate records from ice cores can show resolutions with individual annual layers, ocean sediment cores are greatly compressed with resolutions sometimes no finer than millennia

“What we have is unprecedented among marine records.”

Dating methods such as carbon-14 are useless beyond 30,000 years or so, he said, so Rashid and his colleagues used the ratio of the isotopes oxygen-16 to oxygen-18 as a proxy for temperature in the records. The isotopes were stored in the remains of tiny sea creatures that fell to the ocean bottom over time.

When the researchers compared their record of past climate from the North Atlantic to a similar record taken from an ice core drilled from Dome C in Antarctica, they found it was remarkably similar.

“You can’t miss the similarity between the two records, one from the bottom of the North Atlantic Ocean and the other from Antarctica,” he said. “The record is virtually the same regardless of the location.”

Surprisingly, Rashid’s team was also able to score another first with their analysis of this sediment core – a record of the temperature at the sea surface in the North Atlantic.

They drew on knowledge readily known to chemists that the amount of magnesium trapped in calcite crystals can indicate the temperatures at which the crystals formed. The more magnesium present, the warmer the waters were when the tiny organisms were alive.

They applied this analysis to the remains of the benthic organisms in the cores and were able to develop a record of warming and cooling of the sea surface in the North Atlantic for the last half-million years.

Having this information will be useful as scientists try to understand how quickly the major ocean currents shifted as glacial cycles came and went, Rashid said.

The researchers were also able to gauge the extent of the ancient Laurentide Ice Sheet that covered much of North America during the last 130,000 years.

As that ice sheet calved off icebergs into the Atlantic, Rashid said that the “dirty underbelly” of those icebergs carried gravel out into the ocean. As the bergs melted, the debris fell to the bottom and of the ocean floor. The more debris present, the more icebergs had been released to carry it, meaning that the ice sheet itself had to have been larger.

“Based on this, we’ve determined that the Laurentide Ice Sheet was probably largest during the last glacial cycle than it was during any of the three previous cycles,” he said.

During the last glacial cycle, the Laurentide Ice Sheet was more than a kilometer (.6 miles) thick and extended to several miles north of Ohio State.

Along with Rashid, researchers from the University of South Florida, the University of Bremen in Germany, and the Laboratorio Nacional de Energia e Geologia in Portugal contributed to the work.

Harunur Rashid | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>