A study warns that the critical ocean current is about to ‘collapse’. It would be a global disaster.


Due to global warming, a deep ocean current around Antarctica that has been relatively stable for thousands of years could be heading for a “collapse” in the coming decades.

Such a sudden change could affect the planet’s climate and marine ecosystems for centuries.

So says a recent study published in the peer-reviewed journal Nature.

Cold water flowing near Antarctica drives the deepest flow of a network of currents that stretches across the world’s oceans, known as the overturning circulation. The overturn carries heat, carbon, oxygen and nutrients around the world.

This in turn influences climate, sea levels and the productivity of marine ecosystems. Indeed, the loss of nutrient-rich seawater near the surface could harm fishing, according to the study.

“On the Road to Collapse”

This deep ocean current has remained in a relatively stable state for thousands of years, but with rising greenhouse gas emissions and Antarctic ice melting, Antarctic overturning is expected to slow significantly. over the next few decades.

“Our modeling shows that if global carbon emissions continue at the current rate, the overturning of Antarctica will slow by more than 40% over the next 30 years – and on a trajectory that appears to be heading towards collapse,” said said the study’s lead author, Matthew England, of the University of New South Wales in Australia.

Speaking about the new research, paleoclimatologist Alan Mix told Reuters “it’s amazing to see it happening so quickly”. Mix, a paleoclimatologist at Oregon State University and co-author of the latest assessments by the Intergovernmental Panel on Climate Change, who was not involved in the study, added: “This seems to be accelerating at the moment. That’s the news.”

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Atlantic Current also affected

Such a collapse would also impact a nearby Atlantic Ocean current known as the Atlantic Meridian Overturning Circulation, or AMOC, which carries warm, salty water from the tropics northward across the surface of the ocean. ocean and cold water to the south at the bottom of the ocean.

This current includes the famous Gulf Stream, which affects weather patterns in the United States and Europe. “The main problem for the AMOC right now is the meltwater from Greenland, which is slowing down that current,” England told USA TODAY.

Other studies in recent years of the AMOC have drawn comparisons to the scientifically inaccurate 2004 disaster film “The Day After Tomorrow”, which used such an ocean current stoppage as the film’s premise. In a 2018 study, the authors said a collapse was at least decades away, but would be a disaster.

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Cause of the current slowdown

What causes currents to slow down and potentially collapse? “Climate change is to blame,” England wrote for The Conversation. “As Antarctica melts, more fresh water is flowing into the oceans. This is disrupting the sinking of cold, salty, oxygen-rich water to the ocean floor.”

Specifically, more than 250 trillion tons of this cold, salty, oxygen-rich water flows near Antarctica every year. This water then spreads north and carries oxygen to the depths of the Indian, Pacific and Atlantic oceans.

“If the oceans had lungs, this would be one of them,” England said.

“Put simply, a slowing or collapse of the overturning circulation would alter our climate and marine environment in profound and potentially irreversible ways.” he wrote.

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What impact would that have on the United States?

England told USA TODAY that the main impact for North America would be sea level rise along the East Coast.

Also, another impact of the AMOC collapse would be a transition to a closer La Nina state in the Pacific Ocean, England said. La Niña, a natural cooling of seawater in the tropical Pacific Ocean, affects weather and climate in the United States and around the world.

This tends to make droughts and wildfires worse in the Southwestern United States and more hurricanes in the Atlantic Ocean.

What can be done?

“Our study shows that continued ice melt will not only raise sea levels, but will also alter massive overturning circulation currents that can lead to further ice melt and therefore sea level rise, and damage the climate and ecosystems around the world,” England wrote in the Conversation. “It’s all the more reason to tackle the climate crisis – and fast.”

Contributor: The Associated Press

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