Monday, March 4, 2024
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HomeScienceAtlantic Ocean currents could collapse and close, new study

Atlantic Ocean currents could collapse and close, new study


The Greenland ice sheet could cause the closure of Atlantic Ocean currents.
Reuters/Lucas Jackson

  • Ocean currents in the Atlantic are heading toward a complete shutdown, a new study shows.
  • If that happens, less heat will be exchanged around the world and Europe could freeze.
  • Temperatures in northwestern Europe could drop between 9 and 27 degrees Fahrenheit over decades.

An abrupt shutdown of Atlantic Ocean currents that could freeze large parts of Europe looks a little more likely and closer than before, as a complex new computer simulation finds a “cliff-like” tipping point looming in the future.

A long-worrying nightmare scenario, triggered by the melting of the Greenland ice sheet due to global warming, is still at least decades away, if not more, but perhaps not the centuries it once seemed, finds a new study published Friday in Science Advances.

The study, the first to use complex simulations and include multiple factors, uses a key measurement to track the strength of vital general ocean circulation, which is slowing.

A collapse of the current, called the Atlantic Meridional Overturning Circulation or AMOC, would change climate around the world because it means the shutdown of one of the planet’s key climate and ocean forces.

It would drop temperatures in northwestern Europe by 9 to 27 degrees (5 to 15 degrees Celsius) over decades, extend Arctic ice much further south, further increase heat in the southern hemisphere, change global weather patterns rain and would disrupt the Amazon, the study said. Other scientists said it would be a catastrophe that could cause food and water shortages around the world.

“We are getting closer (to collapse), but we are not sure how much closer,” said the study’s lead author, Rene van Westen, a climate scientist and oceanographer at Utrecht University in the Netherlands. “We are heading towards a turning point.”

If the Atlantic Ocean currents collapsed, the changes would be so abrupt around the world that it would be difficult to adapt, one expert said.
AP Photo/Bob Edme, File

When this global climate calamity, crudely fictionalized in the film “The Day After Tomorrow,” might occur is “the million-dollar question, which unfortunately we cannot answer at the moment,” van Westen said. He said it’s probably a century away, but it could still happen in his lifetime. He just turned 30 years old.

“It also depends on the rate of climate change we are causing as humanity,” van Westen said.

Studies have shown that the AMOC is slowing down, but the problem is a complete collapse or closure. The United Nations Intergovernmental Panel on Climate Change, which is a group of hundreds of scientists that regularly provides authoritative updates on warming, said it has medium confidence that there will not be a collapse before 2100 and generally downplayed the risks. disaster scenarios.

But van Westen, several outside scientists and a study last year say that may not be correct.

Stefan Rahmstorf, head of Earth Systems Analysis at the Potsdam Climate Research Institute in Germany, was not involved in the research, but called it “an important advance in the science of AMOC stability.”

“The new study significantly increases the growing concern about an AMOC collapse in the not-too-distant future,” Rahmstorf said in an email. “We will ignore this at our own peril.”

University of Exeter climate scientist Tim Lenton, who is also not part of the research, said the new study makes him even more concerned about a collapse.

The Thwaites Glacier is melting rapidly and contributes to 4% of global sea level rise.
POT

An AMOC collapse would cause so many waves throughout the global climate that are “so abrupt and severe that it would be almost impossible to adapt to them in some places,” Lenton said.

There are signs that the AMOC has collapsed in the past, but it is still uncertain when and how it will change in the future, said U.S. National Oceanic and Atmospheric Administration oceanographer Wei Cheng, who was not part of the investigation.

The AMOC is part of an intricate global conveyor belt of ocean currents that move different levels of salt and warm water around the world to different depths in patterns that help regulate Earth’s temperature, absorb carbon dioxide and fuel the water cycle. , according to NASA.

When the AMOC closes, there is less heat exchange around the world and “it really affects Europe quite severely,” van Westen said.

For thousands of years, Earth’s oceans have relied on a circulation system that works like a conveyor belt. It keeps moving forward, but slowing down.

The engine of this conveyor belt is off the coast of Greenland, where, as more ice melts due to climate change, more fresh water flows into the North Atlantic and slows everything down, van Westen said. In the current system, colder, deeper, sweeter water heads south, passing through both Americas, and then east, passing through Africa.

Meanwhile, saltier, warmer ocean water from the Pacific and Indian oceans passes the southern tip of Africa, turns toward and around Florida, and continues up the east coast of the United States to Greenland.

The Dutch team simulated 2,200 years of its flow, adding what human-caused climate change affects it. They found after 1,750 years “an abrupt collapse of AMOC,” but so far they cannot translate that simulated timeline into Earth’s real future.

Ocean currents affect climate on a global scale.
Frank Ramspott/Getty Images

The key to monitoring what happens is a complicated flow measurement around the tip of Africa. The more negative that measurement is, the slower AMOC runs.

“This value is becoming more negative due to climate change,” van Westen said. When it gets to a certain point, it’s not a gradual stop but rather something “cliff-like,” she said.

The world should pay attention to the possible collapse of AMOC, said Joel Hirschi, division leader at the UK’s National Oceanography Centre. But there is a larger global priority, he said.

“To me, the rapid increase in temperatures we have seen in recent years and the associated temperature extremes are a more immediate concern than the closure of AMOC,” Hirschi said. “Warming is not hypothetical, but it is already happening and is impacting society.” ___

Read more of AP’s climate coverage at



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