Scientists warn of "irreversible change" in ocean currents that could quickly freeze parts of North America

Scientists warn of "irreversible change" in ocean currents that could quickly freeze parts of North America
Scientists warn of "irreversible change" in ocean currents that could quickly freeze parts of North America

A large Atlantic ocean currents system that includes the Gulf Stream has been disrupted by climate change, scientists said in a new study published Thursday. If this system collapses, it will lead to dramatic changes in weather conditions around the world.

The Atlantic meridional circulation, or AMOC, transports warm salt water from the tropics north at the ocean surface and cold water south at the ocean floor.

"The Atlantic meridional circulation is indeed one of the key circulation systems of our planet," said study author Niklas Burs of the Potsdam Institute for Climate Impact Research in Germany.

Findings from a similar 2018 study prompted comparisons with the 2004 disaster movie The Day After Tomorrow, which used a similar stop in the ocean current as a premise. At the time, the study authors said there were at least decades left before the collapse, but it will be a disaster.

The potential collapse of this system of ocean currents will have serious consequences for the entire globe, the authors of the new study say.

If this circulation stops, it could lead to extreme cold weather in Europe and parts of North America, rising sea levels along the US East Coast and disrupting the seasonal monsoons that provide water for much of the world. It will also threaten the Amazon rainforest and Antarctic ice sheets

Researchers studying ancient climate change have also found evidence that AIOC could shut down abruptly, causing temperature spikes and other dramatic changes in global weather systems.

The study was published Thursday in the peer-reviewed British journal Nature Climate Change.

Climate models have shown that AMOC is at its weakest in over 1000 years. However, it is not known whether the attenuation is due to a change in circulation or a loss of stability.

"The difference is critical," Burs said, "because the loss of dynamic stability means that AIOC is approaching its critical threshold, beyond which a significant and, in practice, probably irreversible transition to a weak regime can occur."

After examining the basic data of the AIOC, the scientists determined that the recent weakening is likely due to the loss of stability: beyond which the circulation system could collapse, "Boers said.

The study says that a number of factors are likely to be important for disrupting the AIOC - factors that add to the direct effect of warming in the Atlantic Ocean on its circulation. These include the influx of fresh water from the melting of the Greenland Ice Sheet, melting sea ice, and increased precipitation and river runoff.

Fresh water is lighter than salt water and reduces the tendency of water to sink deeper from the surface, which is one of the driving forces of tipping.

Levke Caesar from the University of Maynote in Ireland, who was not involved in the study: "The research method cannot give us the exact timing of a possible collapse, but the analysis provides evidence that AIOC has already lost its stability, which I take as a warning that we can be closer to capsizing the AIOC than we think."

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