Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Equatorial water belt slackens

07.02.2002


30 years of slowing Pacific circulation may have changed climate


Less carbon may have reached the atmosphere from the Pacific Ocean surface over the past two decades
© Noella Ballenger



A recent slowing in the circulation of Pacific Ocean waters could have raised Pacific sea surface temperatures. It may even mean that less carbon has reached the atmosphere from the ocean surface over the past two decades.

Across the Pacific, water circulates in two giant loops in the Northern and Southern Hemispheres. It flows from the subtropics to the tropics about at a depth of 100-400 metres, rises to the surface at the equator, and heads back towards the poles at the surface.


This circulation has changed since the 1970s, say Michael McPhaden of the Pacific Marine Environmental Laboratory, Seattle, Washington, and his colleague Dongxiao Zhang of the University of Washington in Seattle1. Thirty years down the line, the amount of subtropical water that reaches the equatorial Pacific sea surface has dropped by 25%.

It had already been noticed that the temperature of the sea surface at the equatorial Pacific has risen by 0.8 oC over the past 30 years. This had puzzled researchers, as cloudy skies in this area have become more frequent over the past 50 years, providing cooling shade. McPhaden and Zhang’s finding explains the warming: the supply of cool subtropical water has dropped.

Getting warmer

The warming that sluggish circulation has brought to the equatorial Pacific may have something to do with the shift in the mid-1970s towards stronger, longer and more frequent El Niño events, in which ocean temperatures and wind patterns fluctuate.

El Niño events cause erratic weather around the world, including droughts in Southeast Africa and floods in parts of South America. But the link between decade-long circulation changes and shifts in the three- to seven-year El Niño cycles needs further investigation.

Nor can connections to global warming be untangled yet. "The beauty of the study is that it works with observations. So we know that the slowing effect is real and not just speculation," says Richard Kleeman, of the Center for Atmosphere Ocean Science, New York.

But it is too early, he thinks, to decide whether - or indeed how - the new results might tie in with the changing climate. "It is a very complex system," he says.

One potential connection lies in the carbon cycle. "The tropical Pacific is the largest oceanic source of carbon dioxide to the atmosphere," McPhaden and Zhang point out. The slowing circulation implies that less of this greenhouse gas has reached the ocean surface over the past decade. So, in the short term, the slowing circulation has helped to keep global warming at bay.

References

  1. McPhaden, M. J. & Zhang, D. Slowdown of the meridional overturning circulation in the upper Pacific Ocean. Nature, 415, 603 - 3608, (2002).

HEIKE LANGENBERG | © Nature News Service
Further information:
http://www.nature.com/nsu/020204/020204-8.html

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>