Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ice Age North Atlantic temperatures, tropical oceans linked

06.10.2006
Evidence that climate change can have a rapid effect on ocean circulation

Sudden shifts in temperature over Greenland and tropical rainfall patterns during the last ice age have been linked for the first time to rapid changes in the salinity of the north Atlantic Ocean, according to research published Oct. 5 in the journal Nature. The results provide further evidence that climate change can have a direct and rapid impact on ocean circulation and chemistry.

"It's a very complicated system," said lead author Matthew Schmidt, who carried out the work as a graduate student at the University of California, Davis, and is now a visiting NOAA Climate and Global Change Postdoctoral Fellow at the Georgia Institute of Technology. "But when it responds, it responds big time."

Schmidt, Maryline Vautravers of Cambridge University in England, and Howard Spero, professor of geology at UC Davis, reconstructed a 45,000-to-60,000-year-old record of ocean temperature and salinity from the chemical traces in fossil shells of tiny planktonic animals recovered from deep sea sediment cores. They compared their results to the record of abrupt climate change recorded in ice cores from Greenland.

At that time, much of North America and Europe was a frigid sheet of ice. But the ice records show repeated patterns of sudden warming, called Dansgaard-Oeschger cycles, when temperatures in Greenland rose by five to 10 degrees Celsius over a few decades.

Those cycles were matched by rapid changes in surface-water salinity in the north Atlantic, the researchers found. The Atlantic got saltier during cold periods, and fresher during warm intervals. The freshening likely reflects shifts in rainfall patterns, mostly in the tropics, Spero said.

"Suddenly, we're looking at a record that links moisture balance in the tropics to climate change," he said.

Close to the tropics, warm, moist air forms a zone of heavy tropical rainfall, called the Intertropical Convergence Zone, which dilutes the salty ocean with fresh water. Today, the tropical rainfall zone reaches into the northern Caribbean, but during the colder periods of the ice age it was pushed much farther south, toward Brazil. That kept fresh water out of the northern Atlantic, so it became more salty, Spero said.

"The most striking thing is that a measurable transition is happening over decades," Spero said.

The circulation, or gyre, in the north Atlantic moves warm, salty water north, keeping Europe relatively temperate. The deep ocean circulation is very sensitive to the saltiness of north Atlantic surface waters, Spero said. Warming climate, higher rainfall and fresher conditions can alter the circulation. During glacial times, reduced circulation caused climate to cool.

The new paper shows that as the climate cooled in Greenland, salinity rapidly increased in the North Atlantic subtropical gyre. The build-up of salt during these cold intervals when the conveyor circulation was reduced would have primed the system to quickly restart on transitions into warm intervals, Schmidt said. However, the actual trigger that caused Atlantic circulation to restart during the ice age is still unknown, he said.

Once warming began, melting ice sheets would have contributed fresh water to the Atlantic, but this would have been partly buffered by the elevated saltiness of the Atlantic.

The research looked at changes during the last ice age, when global temperatures were much lower than today. But the results show that ocean salinity is very sensitive to climate change, and could change rapidly -- over a matter of decades, Spero said.

"The salinity of the north Atlantic is the canary of the climate system," Spero said.

Andy Fell | EurekAlert!
Further information:
http://www.ucdavis.edu

More articles from Earth Sciences:

nachricht NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center

nachricht New research unlocks forests' potential in climate change mitigation
21.04.2017 | Clemson University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

Im Focus: Quantum-physical Model System

Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms

Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...

Im Focus: Glacier bacteria’s contribution to carbon cycling

Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.

A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

New quantum liquid crystals may play role in future of computers

21.04.2017 | Physics and Astronomy

A promising target for kidney fibrosis

21.04.2017 | Health and Medicine

Light rays from a supernova bent by the curvature of space-time around a galaxy

21.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>