According to a recent study, a vital system of ocean currents may already be headed toward collapse, which would have dire consequences for global weather patterns and sea level rise, causing temperatures to climb in some areas and drop sharply in others.
As stated by a study published on February 2, 2024, in the journal Science Advances, scientists have discovered a novel method for detecting an early warning signal for the collapse of these currents using incredibly sophisticated and costly computing equipment. Furthermore, there are already signs that the Earth is moving in this direction as it heats.
The Gulf Stream, which is a part of the Atlantic Meridional Overturning Circulation (AMOC), is like a massive global conveyor belt, carrying warm water from the tropics toward the far North Atlantic, where it cools, gets saltier, and plunges deeply into the ocean before spreading southward. The currents are essential in maintaining the generally mild temperature throughout most of the Northern Hemisphere and transport heat and nutrients to various parts of the world.
The stability of the circulation has been under threat for decades due to climate change, which heats the ocean and melts ice, upsetting the delicate balance between salt and heat that controls the intensity of the currents. The AMOC may slow down or possibly stop entirely as a result of climate change, according to many experts, but it’s still very unclear when and how quickly this may occur. Only since 2004 has the AMOC been continuously observed. Scientists are aware that the AMOC closed more than 12,000 years ago as a result of rapid glacier melting, based on their reconstruction of historical events using materials such as ice cores and ocean sediments. Now, they are rushing to determine whether it may occur again.
Over the course of three months, the scientists ran intricate climate models on a supercomputer, modeling a progressive increase in freshwater to the AMOC due to glacier melt, rainfall, and river runoff, all of which can lower the salinity of the ocean and weaken the currents.
More research is needed, René van Westen, a marine and atmospheric researcher at the University of Utrecht, told CNN, including models that also mimic climate change impacts, like 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. They observed that the AMOC gradually weakened until it abruptly collapsed, marking the first time a collapse has been detectable using these complex models, and the report calls it “bad news for the climate system and humanity.”
The breakdown of the AMOC may have disastrous effects. The study concludes that over a century, temperatures in some regions of Europe would drop by as much as 30 degrees Celsius, resulting in a totally new climate in only a few decades. Sea levels might rise by about one meter (3.3 feet) as a result of the breakdown of the AMOC, according to van Westen.
According to a study conducted in 2021, the AMOC was at its weakest point in the previous 1,000 years. Furthermore, a highly concerning and rather contentious analysis that was released in July of last year concluded that the AMOC might be headed for collapse as early as 2025. However, there are still a great deal of unknowns. Senior scientist Jeffrey Kargel of the Planetary Science Institute in Arizona expressed his suspicion that the idea around the AMOC’s possible impending closure “will remain somewhat controversial until, one year, we know that it is happening.” The AMOC’s strength varies, according to current data, although Hirschi, an associate head of marine systems modeling at the National Oceanography Centre in the UK noted that no signs of a reduction have been seen to date. “A significant unanswered question is whether abrupt changes in the AMOC akin to those observed in the past will transpire as our climate continues to warm.”
According to Rahmstorf, a physical oceanographer at Potsdam University in Germany stated that this work is a piece of that puzzle. “This greatly heightens the growing apprehension regarding an AMOC collapse in the near future,” he remarked. “Ignoring this risk will be at our own peril.”
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