Ocean system that brings heat closer to collapse could plunge Europe into frigid conditions

A sudden cessation of Atlantic currents that could plunge large parts of Europe into polar ice could be more likely than before, as new complex computer simulations reveal a “cliff-like” tipping point is imminent in the future. It looks a little more likely and closer.

The long-worried nightmare scenario caused by the melting of Greenland’s ice sheet due to global warming is at least decades, if not more, away, but perhaps centuries as it once was. It may not have been that long, a new study announced Friday. scientific progress find. The study is the first of its kind to use complex simulations, include multiple components, and use key measurements to track the strength of the critical ocean-wide circulation, which is slowing.

The collapse of the ocean currents, called the Atlantic Meridional Overturning Circulation (AMOC), will change weather around the world because it means one of the key components of Earth’s climate and ocean power will cease. This has resulted in temperatures in northwestern Europe dropping by 5 to 15 degrees Celsius over several decades, Arctic ice spreading further south, heating up the Southern Hemisphere, changing global rainfall patterns, and causing the Amazon River to grow. will be destroyed, the research report said. Other scientists said this would be a catastrophe that could cause global food and water shortages.

“We are getting closer[to collapse]but we don’t know how close,” said study lead author René van Westen, a climate scientist and oceanographer at Utrecht University in the Netherlands. “We are heading towards a tipping point.”

When this global weather disaster happens — it’s completely fictionalized in the movie the day after tomorrow — What could happen is “a million-dollar question that unfortunately we can’t answer at this point,” Van Westen said. He said it’s probably a century away, but it could happen in his lifetime. He just turned 30.

“It also depends on the rate of climate change that we as humans are causing,” van Westen says.

Research shows that AMOC is slowing down, but the question is about complete collapse or closure. The United Nations’ Intergovernmental Panel on Climate Change, a group of hundreds of scientists who regularly publish authoritative updates on global warming, is moderately confident that collapse will not occur by 2100. , and generally downplays disaster scenarios. But Van Westen, several outside scientists and a study last year say that may not be true.

Stefan Rahmstorff, head of the Earth System Analysis Division at Germany’s Potsdam Climate Institute, who was not involved in the study, called it “a major advance in AMOC stability science.”

“The new investigation further raises concerns that AMOC may collapse in the not-too-distant future,” Rahmstorff said in an email. “Ignore this at your peril.”

Tim Renton, a climatologist at the University of Exeter who was not involved in the study, said the new research further raised concerns about the collapse.

AMOC’s collapse would cause so many ripples throughout the world’s climate, Renton said, “so sudden and severe that it would be almost impossible for some regions to adapt.” .

There are signs that the AMOC has collapsed in the past, but it’s still unclear when and how it will change in the future, said Wei Chen, an oceanographer at the National Oceanic and Atmospheric Administration who was not involved in the study. said.

According to NASA, the AMOC is part of a complex global ocean current conveyor belt that moves water of varying levels of salinity and warm water around the world in patterns at varying depths, regulating Earth’s temperature and regulating carbon dioxide. It absorbs water and helps fuel the water cycle.

If AMOC were to close, heat exchange would be reduced around the world, “which would have a very serious impact on Europe,” Van Westen said.

For thousands of years, Earth’s oceans have relied on a circulatory system that moves like a conveyor belt. It’s still going on, but at a slower rate.

The conveyor belt’s engines are located off the coast of Greenland, where as climate change melts more ice, more fresh water flows into the North Atlantic Ocean, slowing everything down, Van Westen said. In the current system, cooler, deeper fresh water moves south through the Americas, then east through Africa. Meanwhile, warm, saline water coming from the Pacific and Indian Oceans passes through the southern tip of Africa, turns around Florida and continues north up the U.S. East Coast to Greenland.

The Dutch team simulated that flow over 2,200 years, adding to it the effects of human-induced climate change. They discovered a “sudden AMOC collapse” after 1750, but have so far been unable to translate that simulated timeline into Earth’s real future. The key to monitoring what’s happening is complex measurements of flows near the tip of Africa. The more negative the measurement, the slower AMOC will run.

“Under climate change, this value is becoming even more negative,” Van Westen said. Once it reaches a certain point, he said, it becomes “like a cliff” rather than a gradual stop.

Joel Hirschi, sector leader at the UK’s National Oceanographic Center, said the world should pay attention to the possibility of AMOC collapse. But there are bigger priorities globally, Hirschi said.

“For me, a more pressing concern than the closure of AMOC is the rapid rise in temperatures and associated temperature extremes that we have witnessed in recent years,” he said. “Global warming is not a hypothesis; it is already happening and it is having an impact on society.”