An impressive current system of the Atlantic Ocean, which plays an important role in the redistribution of heat in our planet’s climate system, is moving at a slower pace in at least 1,600 years. That is the conclusion of a new study published in the journal Nature Geoscience by some of the world’s leading experts in the field.
Scientists believe that part of this slowdown is directly related to our warming climate, because Melting ice Changes the balance in northern water. Its effects can be seen in hurricanes, heat waves and sea level rise. And it encourages concerns that if humans can’t limit warming, the system could eventually reach a tipping point, disrupting patterns in the global environment.
The Gulf Stream along the US East Coast is an integral part of this system, known as the Atlantic Meridianal overturning circulation or AMOC. It was popularized in the 2004 film “The Day After Tomorrow,” in which the tide suddenly stops, causing heavy killer storms around the world, such as a super-charged tornado in Los Angeles and a water wall collapsing. New York City.
Like many sci-fi movies, the plot is based on real concepts but its effects are taken to dramatic extremes. Fortunately, the current abrupt end to expectations is not expected to happen anytime soon – if ever. If it is to eventually shut down – and it is heavily debated – the result will not be more instantaneous than instantaneous life, but its impact over the years and decades will certainly be devastating for our planet.
Recent research has shown that circulation has decreased by at least 15% since the 1950s. In a new study, scientists say the weakening of the present is “unprecedented in the millennium of the past.”
Because everything is connected, the recession is undoubtedly already affecting Earth systems, and by the end of the century it is estimated that rotation could slow by 34% to 45% if we keep the planet warm. Scientists fear that such a recession would put us dangerously close to the tipping point.
Importance of the Global Ocean Conveyor Belt
The equator receives more direct sunlight than the cold poles, thus increasing tropical heat. In an effort to reach equilibrium, the Earth shifts from these tropics to the north and from the poles to the cold south. This is what causes winds to blow and storms to form.
Most of that heat is redistributed by the atmosphere. But the rest of the destinations are slowly being moved by the oceans called the Global Ocean Conveyor Belt – the worldwide system of currents connecting the world’s oceans, moving horizontally and ically all in different directions.
NOAA
Through years of scientific research it has become clear that the Atlantic portion of the conveyor belt – the AMOC – is the engine that drives its work. It moves 100 times the water flow of the Amazon River. Here’s how it works.
In the tropics near Florida, a narrow strip of warm, brackish water, called the Gulf Stream, is carried northward near the surface in the North Atlantic. When it reaches the Greenland region, it cools enough to be more gnse and heavier than the surrounding water, at which point it sinks. Cold water is then carried southwards in cold water currents.
Through proxy records such as ocean sediments, which allow scientists to reconstruct the distant past millions of years ago, scientists know that these currents have the potential to slow down and stop, and that they can change the weather rapidly in the Northern Hemisphere.
An important mechanism of the age, which acts as a lever to control the motion of the AMOC, is the melting of ice-ice and the flow of fresh water into the North Atlantic. This is because fresh water is less salty than seawater, and therefore less ga ense, and it does not sink easily. Too pure water means that the conveyor belt loses the sinking part of its engine and therefore it loses its speed.
Scientists believe that now in places like Greenland, it is happening like ice in the Arctic, One melts at a fast pace Due to human-climate change.
Climate central
Scientists have recently spotted a cold blob called North Atlantic Warming Hole in the Pacific North Atlantic around South Greenland – the only place on the planet that really cools.
The fact that climate models Dello has predicted provides further evidence that it is indicative of excessive Greenland ice melting, more rainfall, and a slower rate of heat transfer northward from tropical directions.
NASA
To find out how unprecedented the recent slowdown of the AMOC is, the research team compiled proxy data taken from natural archives such as sea sediments and ice cores, dating back 1,000 years. This helped them reconstruct the flow history of the AMOC.
The team used a combination of three different types of data to obtain information about the history of ocean currents: temperature patterns in the Atlantic Ocean, the mass properties of subsurface water, and the size of grains of deep sea silt, dating back 1,600 years.
While not every individual piece of proxy data is a complete representation of AMOC evolution, their combination paints a grim picture of the turbulent rotation, says Dr. Levke Caesar, an environmental physicist at the University of Manhattan in Ireland. .
“The results of the study indicate that it was relatively stable until the end of the 19th century,” explains Stefan Rehmstorf from the Potsdam Institute for Climate Impact Research in Germany.
The first significant change in their ocean circulation record occurred in the mid-1800s, after a regional cooling period known as the Little Ice Age, which extended from the 1400s to the 1800s. During this time, cold temperatures often freeze rivers in Europe and destroy crops.
“With the end of the Little Ice Age in about 1850, ocean currents began to decline, with the second and most sharp decline since the middle of the 20th century,” Rahmstorf said. That is likely to be the second decline in recent decades. Burning and emissions of fossil fuels caused global warming.
Nine of the 11 data-sets used in the study showed that 20th-century AMOC vulnerabilities are statistically significant, providing evidence that recession is unprecedented in the modern age.
Impact on storms, heat waves and sea level rise
Caesar says this is already reappearing in the climate systems on both sides of the Atlantic. “As the current slows, more water can flow to the U.S. east coast, raising sea levels. [in places like New York and Boston], ”He explained.
In Europe, on the other side of the Atlantic, evidence shows that hurricanes descending from the Atlantic, as well as heat waves, affect weather patterns.
“In particular, the summer 2015 European heat wave has been linked to record cold in the North Atlantic that year – this potentially contradictory effect as the cold promotes the North Atlantic air pressure pattern that propagates warm air from the south to Europe,” she said.
According to Caesar, as the Earth continues to warm up and the AMOC slows down even more, with more extreme weather events such as the winter hurricane shifting from the Atlantic and possibly more severe storms, these effects are likely to worsen.
CBS News asked Caesar a million-dollar question: if or when the AMOC can reach a tipping point when it leads to a full erection? He replied: “Well, the problem is that we don’t know yet how many degrees of global warming can survive at the AMOC’s tipping point. But the more it does, the more likely it is to do so.”
Moreover, he explained, “Tipping does not mean that this happens instantly, but it does mean that by reaction methods, after crossing the tipping point, the slow cannot be stopped, even if we succeed in reducing global temperatures again.”
Caesar believes that AMOC is likely to tip if we stay below 2 degrees Celsius of global warming, but if we increase the probability of an increase in tipping to 3 or 4 degrees Celsius. Staying below 2 degrees Celsius (3.6 degrees Fahrenheit) is the goal of the Paris Agreement, which The US just joined.
If the tipping point is exceeded and the AMOC stops, it experiences cooling in the Northern Hemisphere due to a significant reduction in tropical heat pushed to the north. But beyond that, Caesar says science does not yet know exactly what will happen. “It’s part of the risk.”
But all of this has no human agency, and the outcome we make will depend on how quickly we transition from fossil fuels.
“Whether we cross the tipping point by the end of this century depends on the amount of warming, ie the amount of greenhouse gases released into the atmosphere,” Caesar explains.
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