Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
. 24/7 Space News .




ICE WORLD
Arctic current flowed under deep freeze of last ice age
by Staff Writers
New York NY (SPX) Jun 02, 2013


Arctic sea ice formation feeds global ocean circulation. New evidence suggests that this dynamic process persisted through the last ice age.

During the last ice age, when thick ice covered the Arctic, many scientists assumed that the deep currents below that feed the North Atlantic Ocean and help drive global ocean currents slowed or even stopped.

But in a new study in Nature, researchers show that the deep Arctic Ocean has been churning briskly for the last 35,000 years, through the chill of the last ice age and warmth of modern times, suggesting that at least one arm of the system of global ocean currents that move heat around the planet has behaved similarly under vastly different climates.

"The Arctic Ocean must have been flushed at approximately the same rate it is today regardless of how different things were at the surface," said study co-author Jerry McManus, a geochemist at Columbia University's Lamont-Doherty Earth Observatory.

Researchers reconstructed Arctic circulation through deep time by measuring radioactive trace elements buried in sediments on the Arctic seafloor. Uranium eroded from the continents and delivered to the ocean by rivers, decays into sister elements thorium and protactinium.

Thorium and protactinium eventually attach to particles falling through the water and wind up in mud at the bottom.

By comparing expected ratios of thorium and protactinium in those ocean sediments to observed amounts, the authors showed that protactinium was being swept out of the Arctic before it could settle to the ocean bottom. From the amount of missing protactinium, scientists can infer how quickly the overlying water must have been flushed at the time the sediments were accumulating.

"The water couldn't have been stagnant, because we see the export of protactinium," said the study's lead author, Sharon Hoffmann, a geochemist at Lamont-Doherty.

The upper part of the modern Arctic Ocean is flushed by North Atlantic currents while the Arctic's deep basins are flushed by salty currents formed during sea ice formation at the surface.

"The study shows that both mechanisms must have been active from the height of glaciation until now," said Robert Newton, an oceanographer at Lamont-Doherty who was not involved in the research.

"There must have been significant melt-back of sea ice each summer even at the height of the last ice age to have sea ice formation on the shelves each year. This will be a surprise to many Arctic researchers who believe deep water formation shuts down during glaciations."

The researchers analyzed sediment cores collected during the U.S.-Canada Arctic Ocean Section cruise in 1994, a major Arctic research expedition that involved several Lamont-Doherty scientists. In each location, the cores showed that protactinium has been lower than expected for at least the past 35,000 years.

By sampling cores from a range of depths, including the bottom of the Arctic deep basins, the researchers show that even the deepest waters were being flushed out at about the same rate as in the modern Arctic.

The only deep exit from the Arctic is through Fram Strait, which divides Greenland and Norway's Svalbard islands. The deep waters of the modern Arctic flow into the North Atlantic via the Nordic seas, contributing up to 40 percent of the water that becomes North Atlantic Deep Water-known as the "ocean's lungs" for delivering oxygen and salt to the rest of world's oceans.

One direction for future research is to find out where the missing Arctic protactinium of the past ended up. "It's somewhere," said McManus. "All the protactinium in the ocean is buried in ocean sediments.

If it's not buried in one place, it's buried in another. Our evidence suggests it's leaving the Arctic but we think it's unlikely to get very far before being removed."

Other authors are William Curry, president and director of Bermuda Institute of Ocean Sciences and emeritus scientist at Woods Hole Oceanographic Institution, and L. Susan Brown-Leger, a retired Woods Hole researcher.

.


Related Links
The Earth Institute at Columbia University
Beyond the Ice Age






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





ICE WORLD
Russian scientists make rare find of 'blood' in mammoth
Moscow (AFP) May 29, 2013
Russian scientists claimed Wednesday they have discovered blood in the carcass of a woolly mammoth, adding that the rare find could boost their chances of cloning the prehistoric animal. An expedition led by Russian scientists earlier this month uncovered the well-preserved carcass of a female mammoth on a remote island in the Arctic Ocean. Semyon Grigoryev, the head of the expedition, s ... read more


ICE WORLD
NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity

Moon dust samples missing for 40 years found in Calif. warehouse

Unusual minerals in moon craters may have been delivered from space

Moon being pushed away from Earth faster than ever

ICE WORLD
Mars Curiosity Rover Provides Strong Evidence for Flowing Water

Ten Years At Mars: New Global Views Plot History Of The Red Planet

Flowing Water Transported Sand, Rocks Along Martian Streambed

Leicester Scientist Helps Discover Ancient Streambed On Mars

ICE WORLD
White House moves to curb 'patent trolls'

A certain level of stress is necessary

Northrop Grumman-Built Modular Space Vehicle Nears Completion of Manufacturing Phase

French government posts space counsellor in Bangalore

ICE WORLD
Shenzhou-10 spacecraft to be launched in mid-June

Sizing Up Shenzhou 10

Rollout for Shenzhou 10

Soft Pedal for Shenzhou 10

ICE WORLD
International trio takes shortcut to space station

Science and Maintenance for Station Crew, New Crew Members Prep for Launch

ESA Euronews: Living in space

Next destination: space

ICE WORLD
The Future of Space Launch

Rocket Engine Maker Proton-PM to Invest in New Products

Russia Launches European Telecoms Satellite

Ariane poised to launch first 20 ton payload into orbit

ICE WORLD
In feat, telescope directly spots lightweight exoplanet

Scouting for Not-So-Distant Worlds

Lightest exoplanet imaged so far?

Big Weather on Hot Jupiters

ICE WORLD
Another American High Frontier First: 3-D Manufacturing in Space

Charred micro-bunny sculpture shows promise of new material for 3-D shaping

Flexible opals make for some colourful material science

The formula for turning cement into metal




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement