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article imageClimate change could result in collapse of major ocean current

By Karen Graham     Jan 6, 2017 in Science
Researchers are suggesting that as a result of climate change, Atlantic Ocean current patterns may not be as stable as climate models suggest. This could raise the possibility of a collapse of the ocean's currents, causing a catastrophic change.
You may be familiar with the 2004 disaster film, "The Day After Tomorrow." In the movie, climate change causes a failure in the Atlantic Ocean's major current cycle, creating catastrophic natural disasters and establishing freezing conditions in North America and Europe.
The major current the movie was referring to is called the Atlantic Meridional Overturning Circulation (AMOC). It can be likened to a climate conveyor belt. The AMOC is a deep-sea system that circulates warm water from the South Atlantic Ocean and the Gulf of Mexico to the North Atlantic, where it sinks and cools, according to Live Science.
US Secretary of State John Kerry said he first became involved in the climate issue in the early 199...
US Secretary of State John Kerry said he first became involved in the climate issue in the early 1990s and had seen scientific evidence of change grow to be overwhelming
Mark Ralston, POOL/AFP
Then the waters circulate back down to the south in a clockwise motion. This is what allows the UK and parts of Europe to enjoy a relatively moderate climate, reports the CBC News Canada.
Current climate models have found that climate change will affect the AMOC, but not in any significant way, as long as the AMOC remains stable. And this is the gist of a new study that suggests that maybe the AMOC is not quite as stable as the models have suggested because they suffer from biases.
An international team of researchers, funded by the National Science Foundation, the Department US of Energy and the Ministry of Science and Technology of the People’s Republic of China found that the possibility of a collapse of the AMOC has been overlooked in climate change studies.
Using current climate models, the scientists found that in attempting to ascertain the effects of an increase in greenhouse gasses, the behavior of a relatively stable AMOC would be influenced by a warming North Atlantic, but not to any great degree. But what if the bias, a stable AMOC, was removed?
So when the researchers removed the bias and reran simulations, their results prompted them to predict a collapse of the AMOC within the next 300 years, setting into motion a large-scale cooling in the North Atlantic. The event would stop the Atlantic's circulation and no warm water would be circulating back to the South Atlantic regions.
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Scripps Institute of Oceanography/Science Advances
"If we correct the stability bias of the AMOC … and then add global warming forcing, the AMOC actually collapses after a couple of hundred years," Wei Liu, a former Scripps Institute of Oceanography postdoctoral researcher now at Yale University and lead author of the paper told CBC News.
Why is this research so important?
Basically, this is NOT a screaming headline foretelling a coming disaster. Instead, the research is important because it points out a bias in current climate prediction models, says Wei.
“A bias-corrected model puts the AMOC in a realistic stability regime and predicts a future AMOC collapse with prominent cooling over the northern North Atlantic and neighboring areas. Therefore, our study has enormous implications for regional and global climate change.”
The research is also important because it explores an issue that has been central to an on-going debate among climate scientists, and that is the stability of the AMOC. The Intergovernmental Panel on Climate Change (IPCC) issues periodic reports on the latest research on climate change, and those reports are all based on the AMOC remaining stable.
In the last two of the IPCC's reports, it was acknowledged that while the AMOC is relatively stable and will not collapse, there is the possibility it could weaken as the climate continues to change. So a revision and correcting of the bias in climate models might give scientists a more accurate picture of global warming and its impacts.
This very interesting research, entitled "Overlooked possibility of a collapsed Atlantic Meridional Overturning Circulation in warming climate," was published in the journal Science Advances on January 4, 2017.
More about Climate change, Atlantic ocean, current circulation, AMOC, climate conveyer belt
 
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