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| Warm water heads north toward Europe, cools, eventually sinks, goes back south, warms up and the process repeats itself. However, fresh water melting off the Arctic could stop this circulation, causing extreme, sudden changes in climate, especially in Europe. |
I should probably explain that one.
The AMOC is the Atlantic Meridonal Overturning Circulation. It brings warm water from south to the northern Atlantic Ocean. That rent brings carbon, nutrients and other stuff to sustain a healthy population of fish and other aquatic animals.
It also keeps western and northern Europe much warmer than it would be, considering how far north that area is. If this circulation collapses, that region of the world would turn much, much colder in the winter. And much more variable in the summer.
The problem is, climate change could make this circulation stop. It's already slowing down.
For years, there's been a lot of speculation among scientists as to how far climate change needs to go before AMOC collapses. Now, a group of scientists are saying the risks of this circulation collapsing are underestimated.
"The climate scientists quoted a 2023 Intergovernmental Panel on Climate Change (IPCC) report, which said there is 'medium confidence' the AMOC won't abruptly collapse by 2100. If such a low likelihood event did happen, the report added, 'it would very likely cause abrupt shifts in regional weather patterns and water cycle."
Well, at least we have time to plan, right?
But what if it happens sooner? It seems a growing body of researchers think it might. Some scientists say it could happen as soon as the middle of this century, say 20 or 30 years from now. That's not a lot of time for millions of people to brace themselves for sudden, radical shifts in the climate.
Nordic nations would probably stop being able to grow their own food under the extreme weather conditions.
That would be bad enough. But a collapse of AMOC would reverberate around the world, with big time climate changes worldwide.
An AMOC collapse would probably reverse climate change in the northern hemisphere, but that would not be a good thing.
Some European cities would get 10 to 20 degrees colder within just a few decades. Meanwhile, The Atlantic Ocean sea level would rise by more than two feet. Meanwhile, the southern hemisphere would turn much warmer than it already is, and the Antarctic ice cap would melt much faster than it is now, according to renewablematter.eu.
Overall, this circulation's shutdown would also reduce the worlds supply of food.
As I noted, we don't know when, or even if this nightmare scenario will happen. But scientists are definitely worried.
The AMOC is slowing down, and could collapse, because of melting ice sheets in Greenland and other areas of the Arctic adjacent to the North Atlantic.
The water flowing up from the south and keeping Europe mild in this AMOC circulation is pretty salty. Once the salty water makes it that far north, it cools and sinks because the high salinity increases its density.
Fresh water from all that ice melting off of Greenland reduces the saltiness in the water, which in turn reduces the density of the water. So less surface water sinks, which slows the flow of the current. Scientists worry if too much fresh water from ice melt flows into the Atlantic, it'll shut off the current entirely.
Scientists have done research on how much fresh water it would take to shut the current off. But past studies uses simulations that provided unrealistic scenarios involving a bunch of fresh water gushing into the Atlantic all at once.
In February this year, scientists from Utrecht University in the Netherlands used a complex climate model to simulate the collapse of the AMOC and discovered that it could be closer than previously thought.
The Dutch scientists' model kept gradually adding more and more fresh meltwater to the North Atlantic and concluded that could lead to a sudden collapse of the currents in less than 100 years. However, they weren't able to come up with a statistically reliable estimate of exactly when that would happen.
We better hope it doesn't happen anytime soon. If it does, it'll make the kinds of climate disruptions we're already seeing now just a pleasant walk in the park.
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