Crucial ocean current system could be on course to collapse with catastrophic impacts on global weather | CNN (2024)

Crucial ocean current system could be on course to collapse with catastrophic impacts on global weather | CNN (1)

Waves in the North Atlantic Ocean near Gatklettur, Iceland, March 2020.


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. University of Cambridge/British Antarctic Survey Related article Scientists discover an alarming change in Antarctica’s past that could spell devastating future sea level rise

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 — representingice 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) Felipe Dana/AP Related article A crucial system of ocean currents is heading for a collapse that ‘would affect every person on the planet’

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 torelatively 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 weakerthan 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.”

Crucial ocean current system could be on course to collapse with catastrophic impacts on global weather | CNN (2024)


Crucial ocean current system could be on course to collapse with catastrophic impacts on global weather | CNN? ›

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.

Could a crucial ocean current system could be on course to collapse with catastrophic impacts on global weather? ›

Scientists warn that a crucial ocean current could collapse, altering global weather – the Los Angeles Times. Scientists are sounding the alarm that a crucial component of the planet's climate system is in gradual decline and could one day reach a tipping point that would radically alter global weather patterns.

What key ocean current is close to collapse study suggests? ›

The bad climate news keeps coming: A new study adds to the evidence that the Atlantic Ocean's critical system of currents will eventually collapse in response to melting ice sheets in Greenland (thanks, global warming).

Do scientists warn that a crucial Atlantic ocean current is approaching collapse? ›

A vital Atlantic current that includes the Gulf Stream and keeps our climate in check may be giving off a warning sign of collapse. Scientists have discovered a key warning sign before a crucial Atlantic current collapses and plunges the Northern Hemisphere into climate chaos.

Could the ocean current system shut down as early as 2025? ›

The Gulf Stream system could collapse as soon as 2025, a new study suggests. The shutting down of the vital ocean currents, called the Atlantic Meridional Overturning Circulation (Amoc) by scientists, would bring catastrophic climate impacts.

What ocean current is about to collapse? ›

A collapse of the current — called the Atlantic Meridional Overturning Circulation or AMOC — would change weather worldwide because it means a shutdown of one of key the climate and ocean forces of the planet.

Is the ocean ecosystem collapsing? ›

The global ecosystem is in far greater danger than scientists previously thought, according to a new study — and that's really saying something. The research predicts that without dire action to reverse global climate change, entire ocean ecosystems could suddenly collapse this decade, The Guardian reports.

What happens if the ocean currents collapse? ›

Disruption of the Atlantic Meridional Overturning Current could freeze Europe, scorch the tropics and increase sea level rise in the North Atlantic. The tipping point may be closer than predicted in the IPCC's latest assessment.

What did they explain happened to the ocean currents and why what is causing the extreme weather the day after tomorrow? ›

The movie The Day After Tomorrow is loosely based on the theory of “abrupt climate change.” The plot of the movie is that, as a result of global warming, ocean currents that circulate water around the world shut down, heating up the tropics and cooling the North Atlantic.

What are 3 main factors driving ocean currents? ›

Ocean currents are driven by wind, water density differences, and tides. Oceanic currents describe the movement of water from one location to another. Currents are generally measured in meters per second or in knots (1 knot = 1.85 kilometers per hour or 1.15 miles per hour).

Is the Earth's ocean in serious trouble? ›

Without a healthy ocean, humans cannot thrive. But the ocean has taken a pummelling and we have not been treating it well. It is facing down three huge threats: overfishing, pollution and climate change. Most of these are caused by human mismanagement.

How would AMOC collapse affect North America? ›

An AMOC collapse would have devastating consequences

Sea levels in the North Atlantic would surge by up to a meter as water piled up in the region, and the bottom of the ocean would run short on oxygen — killing the creatures that live in its depths.

Is the Gulf Stream approaching collapse? ›

It estimates Amoc could collapse between 2025 and 2095. The analysis is based on greenhouse gas emissions rising in the same way as they have done thus far. If emissions started to reduce, the world would have more time to keep temperatures below the point at which Amoc would, potentially, collapse.

Will the ocean be dead by 2050? ›

Despite being treated as humanity's rubbish dump for decades, the oceans of the world are proving remarkably resilient, says a new scientific review. Building on that resilience could lead to a full recovery within three decades, the researchers argue.

What will happen if the Gulf Stream shuts down? ›

The result: Dangerous cold in the North

Regions that are influenced by the Gulf Stream receive substantially less heat when the circulation stops. This cools the North American and European continents by a few degrees.

What effects do the ocean's currents have on the global climate? ›

Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth's surface.

How does ocean currents affect natural disasters? ›

By transferring heat energy around the globe, ocean currents shape both local weather conditions and global climate. For example, warm ocean currents create the conditions that spawn tropical cyclones and hurricanes—local severe weather conditions.

What events can cause catastrophic change in the Earth system? ›

Some examples of events that cause catastrophic change include natural disasters such as earthquakes, tsunamis, volcanic eruptions, hurricanes, and floods; human-induced disasters such as nuclear accidents, industrial accidents, and oil spills; and potential future risks like pandemics, climate change, artificial ...


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