Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Shutdown of circulation pattern could be disastrous

16.12.2004


If global warming shuts down the thermohaline circulation in the North Atlantic Ocean, the result could be catastrophic climate change. The environmental effects, models indicate, depend upon whether the shutdown is reversible or irreversible.

"If the thermohaline shutdown is irreversible, we would have to work much harder to get it to restart," said Michael Schlesinger, a professor of atmospheric sciences at the University of Illinois at Urbana-Champaign and a co-author of a report presented at the American Geophysical Union meeting in San Francisco. "Not only would we have the very difficult task of removing carbon dioxide from the atmosphere, we also would have the virtually impossible task of removing fresh water from the North Atlantic Ocean."

The thermohaline circulation is driven by differences in seawater density, caused by temperature and salinity. Like a great conveyor belt, the circulation pattern moves warm surface water from the southern hemisphere toward the North Pole. Between Greenland and Norway, the water cools, sinks into the deep ocean, and begins flowing back to the south.



"This movement carries a tremendous amount of heat northward, and plays a vital role in maintaining the current climate," Schlesinger said. "While shutting it down due to global warming would not cause an ice age, as was depicted in a recent blockbuster movie, ’The Day After Tomorrow,’ eastern North America and western Europe would nevertheless experience a shift in climate."

Paleoclimate records constructed from Greenland ice cores have revealed that the thermohaline circulation has, indeed, shut down in the past and caused regional climate change. As the vast ice sheet that covered much of North America during the last ice age finally receded, the meltwater flowed out the St. Lawrence and into the North Atlantic.

"The additional fresh water made the ocean surface less dense and it stopped sinking, effectively shutting down the thermohaline circulation," Schlesinger said. "As a result, Greenland cooled by about 7 degrees Celsius within several decades. When the meltwater stopped, the circulation pattern restarted, and Greenland warmed."

Since the system has previously shut down by itself, "it is not unlikely that it will do so again, especially with our help in pouring greenhouse gases into the atmosphere," Schlesinger said. "Higher temperatures due to global warming could add fresh water to the northern North Atlantic by increasing the precipitation and by melting nearby sea ice, mountain glaciers and the Greenland ice sheet. This influx of fresh water could reduce the surface salinity and density, leading to a shutdown of the thermohaline circulation.

Schlesinger and his team simulated the potential effects with an uncoupled ocean general circulation model and with it coupled to an atmosphere general circulation model. They found that the thermohaline circulation shut down irreversibly in the uncoupled model simulation, but reversibly in the coupled model simulation.

"The different results occurred because of a crucial feedback mechanism that appeared only in the coupled model simulation," Schlesinger said. "Enhanced evaporation increased the salinity and density of the ocean surface, offsetting the effects of additional fresh water."

"The irreversible shutdown of the thermohaline circulation thus appears to be an artifact of the model, rather than a likely outcome of global warming," Schlesinger said. "But, because the possibility of an irreversible shutdown cannot be excluded, suitable policy options should continue to be explored. Doing nothing to abate global warming would be foolhardy if the thermohaline circulation shutdown is irreversible."

Coauthors are U. of I. graduate student Jianjun Yin, research specialist Natasha Andronova, research programmer Bin Li, and Princeton University researcher Sergey Malyshev.

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

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

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>