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Critical Atlantic Ocean current system is showing early signs of collapse, prompting warning from scientists

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CNN
 — 
A crucial system of ocean currents may already be on course to collapse, according to a new report, with alarming implications for sea level rise and global weather — leading temperatures to plunge dramatically in some regions and rise in others.

Using exceptionally complex and expensive computing systems, scientists found a new way to detect an early warning signal for the collapse of these currents, according to the study published Friday in the journal Science Advances. And as the planet warms, there are already indications it is heading in this direction.

The Atlantic Meridional Overturning Circulation (the AMOC) — of which the Gulf Stream is part — works like a giant global conveyor belt, taking warm water from the tropics toward the far North Atlantic, where the water cools, becomes saltier and sinks deep into the ocean, before spreading southward.

The currents carry heat and nutrients to different areas of the globe and play a vital role in keeping the climate of large parts of the Northern Hemisphere relatively mild.

For decades, scientists have been sounding the alarm on the circulation’s stability as climate change warms the ocean and melts ice, disrupting the balance of heat and salt that determines the currents’ strength.

While many scientists believe the AMOC will slow under climate change, and could even grind to a halt, there remains huge uncertainty over when and how fast this could happen. The AMOC has only been monitored continuously since 2004.

A scientist holds a piece of the ice core extracted from West Antarctica showing air bubbles.

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Scientists do know — from building a picture of the past using things like ice cores and ocean sediments — the AMOC shut down more than 12,000 years ago following rapid glacier melt.

Now they are scrambling to work out if it could happen again.

This new study provides an “important breakthrough,” said René van Westen, a marine and atmospheric researcher at the University of Utrecht in the Netherlands and study co-author.

The scientists used a supercomputer to run complex climate models over a period of three months, simulating a gradual increase of freshwater to the AMOC — representing ice melt as well as rainfall and river runoff, which can dilute the ocean’s salinity and weaken the currents.

As they slowly increased the freshwater in the model, they saw the AMOC gradually weaken until it abruptly collapsed. It’s the first time a collapse has been detectable using these complex models, representing “bad news for the climate system and humanity,” the report says.

What the study doesn’t do, however, is give timeframes for a potential collapse. More research is needed, van Westen told CNN, including models which also mimic climate change impacts, such as increasing levels of planet-heating pollution, which this study did not.

“But we can at least say that we are heading in the direction of the tipping point under climate change,” van Westen said.

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The impacts of the AMOC’s collapse could be catastrophic. Some parts of Europe might see temperatures plunge by up to 30 degrees Celsius over a century, the study finds, leading to a completely different climate over the course of just a decade or two.

“No realistic adaptation measures can deal with such rapid temperature changes,” the study authors write.

Countries in the Southern Hemisphere, on the other hand, could see increased warming, while the Amazon’s wet and dry seasons could flip, causing serious disruption to the ecosystem.

The AMOC’s collapse could also cause sea levels to surge by around 1 meter (3.3 feet), van Westen said.

Stefan Rahmstorf, a physical oceanographer at Potsdam University in Germany, who was not involved with the study, said it was “a major advance in AMOC stability science.”

“It confirms that the AMOC has a tipping point beyond which it breaks down if the Northern Atlantic Ocean is diluted with freshwater,” he told CNN.

Previous studies finding the AMOC’s tipping point used much simpler models, he said, giving hope to some scientists that it might not be found under more complex models.

This study crushes those hopes, Rahmstorf said.

FILE - This early Friday, Aug. 16, 2019 file photo shows an aerial view of large Icebergs floating as the sun rises near Kulusuk, Greenland. Greenland has been melting faster in the last decade, and this summer, it has seen two of the biggest melts on record since 2012. A special United Nations-affiliated oceans and ice report released on Wednesday, Sept. 24, 2019 projects three feet of rising seas by the end of the century, much fewer fish, weakening ocean currents, even less snow and ice, and nastier hurricanes, caused by climate change. (AP Photo/Felipe Dana)
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Joel Hirschi, associate head of marine systems modeling at the National Oceanography Centre in the UK, said the study was the first to use complex climate models to show the AMOC can flip from “on” to “off” in response to relatively small amounts of freshwater entering the ocean.

But there are reasons to be cautious, he added. Even though the study used a complex model, it still has a low resolution, he said, meaning there could be limitations in representing some parts of the currents.

This study adds to the growing body of evidence that the AMOC may be approaching a tipping point — and that it could even be close.

A 2021 study found that the AMOC was weaker than any other time in the past 1,000 years. And a particularly alarming — and somewhat controversial — report published in July last year, concluded that the AMOC could be on course to collapse potentially as early as 2025.

Yet huge uncertainties remain. Jeffrey Kargel, senior scientist at the Planetary Science Institute in Arizona, said he suspected the theory of a potentially imminent shutdown of the AMOC “will remain somewhat controversial until, one year, we know that it is happening.”

He likened its potential collapse to the “wild gyrations of a stock market that precede a major crash” — it’s nearly impossible to unpick which changes are reversible, and which are a precursor to a disaster.

Modern data shows the AMOC’s strength fluctuates, but there is no observed evidence yet of a decline, Hirschi said. “Whether abrupt changes in the AMOC similar to those seen in the past will occur as our climate continues to warm is an important open question.”

This study is a piece of that puzzle, Rahmstorf said. “(It) adds significantly to the rising concern about an AMOC collapse in the not too distant future,” he said. “We will ignore this risk at our peril.”

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Yes of course we’re causing climate change. It’s a simple math problem. More carbon means more warming. Which part of that don’t you understand?  Yes the earth was a snowball once. So what? You, with your smug skepticism, who knows nothing about science except that the earth is 4.5 billion years old, know more than climate scientists? You have the special knowledge that no one else has?  Grow up. Just because “the climate always changes” doesn’t mean we’re not causing it to change right now. That’s like saying your weight has always fluctuated so it doesn’t depend on what you shove in your mouth every day. It’s also like saying you’re going to die anyway so why not hasten it? And for the person above who said we have only been recording temperature for 170 years, that’s just so uninformed.  Scientists can tell climatic conditions from way back in the past with all kinds of methods. What is so hard to understand?  *  The weather man calling something the storm of the century has nothing to do with it. And rapid climate change will be very hard to deal with. It already is for many people all over the world. 

 

 

Edited by TimS
politics

(*member formerly known as 'Robert Yacoub')

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The climate won't change in a decade or 2 or 3.  Our weather cycles from warm to cold all the time for 5 or 10 years.  None of us will be here to see real climate change.  This year the climate has change in Florida ,terrible cold and wet.I hate it but it is what is . Next year it will probably be back to warm and dry.

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Climate change is a natural cycle of Mother Nature. For any person to think that man can fix it is just plain hog wash.

The planet was 9 degrees warmer when the dinosaurs walked it.

We survived 12,000 years ago during the ice age. I suppose man made that happen  too.

We also survived when the AMOC stopped  as well as per the article.

If humans don't die from a super virus or nuclear war, Mother Nature will make the correction and the planet will enter it’s next phase of dominance.

 

 

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On 2/10/2024 at 12:21 AM, Fisherman888 said:

Yes of course we’re causing climate change. It’s a simple math problem. More carbon means more warming. Which part of that don’t you understand?  Yes the earth was a snowball once. So what? You, with your smug skepticism, who knows nothing about science except that the earth is 4.5 billion years old, know more than climate scientists? You have the special knowledge that no one else has?  Grow up. Just because “the climate always changes” doesn’t mean we’re not causing it to change right now. That’s like saying your weight has always fluctuated so it doesn’t depend on what you shove in your mouth every day. It’s also like saying you’re going to die anyway so why not hasten it? And for the person above who said we have only been recording temperature for 170 years, that’s just so uninformed.  Scientists can tell climatic conditions from way back in the past with all kinds of methods. What is so hard to understand?  *  The weather man calling something the storm of the century has nothing to do with it. And rapid climate change will be very hard to deal with. It already is for many people all over the world. 

Haha. 
 

the one truth is greed.  
 

someone is manipulating someone else to take money from their family and take most of it while redistributing some of it.  
 

 

the answer to 99.99 out of 100 questions is always $$$$.  
 

****tttt be that way in the ghetto and ****tt b that way on Wall Street and in Silicon Valley and everywhere 

 

 

Your FEAR is causing you to believe this garbage and you want to take money from my kids

 

 

no thanks.  

 

the planet will be just fine regatdless

 

 

Edited by TimS
quote edited

if we're looking for a shark we're not gonna find him on the land

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44 mins ago, RegDunlop said:

Haha. 
 

the one truth is greed.  
 

someone is manipulating someone else to take money from their family and take most of it while redistributing some of it.  
 

 

the answer to 99.99 out of 100 questions is always $$$$.  
 

****tttt be that way in the ghetto and ****tt b that way on Wall Street and in Silicon Valley and everywhere 

 

 

Your FEAR is causing you to believe this garbage and you want to take money from my kids

 

 

no thanks.  
 

 

the planet will be just fine regatdless

Dumb. What do feelings or fears have anything to do with scientific measurements? What money from your kids? Ignorance. Greening the economy expands the economy and also disentangles us from oil geopolitics so everything is not dependent on the price of gas. You are the one that fears change. Like a buggy driver fearing cars. What exactly is it that bothers you about the idea that if we keep adding carbon dioxide and leaked methane to the atmosphere it will warm up. It IS warming up rapidly. This is denial is stupid it’s breathtaking. This has been known for over 100 years. Decades ago scientists predicted the list of things that would happen and they have happened, not because anyone feared anything. Because that’s how the laws of physics and chemistry work. It’s not about your feelings. You all need to grow up and stop the magical thinking. “Everything will be alright” is the most infantile, intellectually lazy thing to say. YOU have no idea how everything will turn out. And maybe everything will be alright for you. But you are not the only one that matters, and neither is your family. The great thing about this country is nobody will ever force you to by an electric car or whatever. If infrastructure has to be built to accommodate green energy that requires more taxes or borrowing, trust me, you will never feel the impact. Did you know there are hundreds of billions in unpaid taxes from the wealthy in this country every year. Why don’t you worry about that?

(*member formerly known as 'Robert Yacoub')

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Just now, Fisherman888 said:

. Decades ago scientists predicted the list of things that would happen and they have happened, not because anyone feared anything. 

Decades ago (the 70s) those same climate scientists were predicting that we were entering the next ice age.

 

Talk to me when you get China and India on the same page as US for reducing warming emissions.

 

And another question the nobody ever wants to answer is where are the metrics on which to base success and failure?

 

BTW, there's nothing wrong with trying to have a cleaner environment.

 

Stop using climate change as a hammer to bludgeon humanity.

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