A new study fuels concerns about a very important current in the Atlantic Ocean

The so-called AMOC lost stability in the last century. We may now be heading towards a tipping point, which could have far-reaching consequences for the (European) climate.

NS ‘The rotation of the Atlantic meridian inversion– or AMOC for short – is one of the most important circulatory systems on our planet. However, scientists have sounded the alarm before. Because this Atlantic water pump has never been as weak as it has been in the last thousand years. in a New study The researchers once again took a closer look at the developments. This leads to some disturbing new discoveries.

More about AMOC
The Atlantic Zulu inversion is a system of ocean currents that also includes the well-known warm Gulf Stream. These currents carry warm water from the equator to the northern part of the Atlantic Ocean. There, the water emits this heat into the atmosphere and thus ensures the heating of Western Europe. By releasing that heat, you’re left with cool water. This sinks to a greater depth and then travels all the way to Antarctica, ending up across the Gulf of Mexico to the tropics, where the story begins all over again. Thus the system transfers approximately 20 million cubic meters of water per second and exerts a significant influence on the climate of Western Europe, but also affects the global weather system.

You can think of the AMOC as a kind of heartbeat, which pumps water around at a constant rate. But over the past century, the global heart rate has slowed and slowed to a rate not seen in more than a thousand years. Researchers have previously shown that the Great Ocean Current System has been unstable for at least the past few decades. For example, the water around which the AMOC revolves has slowed by about 15 percent since the 1950s. Since the AMOC exerts such a large influence on weather systems, “cardiac arrest” can have severe consequences.

critical threshold
So the question is what the future will bring. “We know from some computer simulations and data from Earth’s past that in addition to the strong current, the AMOC can also flow much weaker,” explains researcher Niclas Boers. “This means that a sudden transition between the two trading modes is in principle possible.” So far, however, the question remains whether the current weakness corresponds to a change in the average trading condition, or whether it is accompanied by an actual loss of dynamic stability. “Difference is crucial,” Brewers asserts. “The loss of dynamic stability means that the AMOC has reached a critical threshold. This means an irreversible transition to a weak current.”

turning point
In the study, the researchers decided to search for answers. Although there is unfortunately no long-term data on the strength of the AMOC, AMOC itself leaves “breadcrumbs” in the form of sea surface temperature and salinity of the Atlantic. “Detailed analysis of these crumbs suggests that AMOC weakening over the past century appears to be accompanied by a loss of stability,” Brewers concludes. In other words, a weak heart rate is not a harmless fluctuation. This could mean that we are currently heading to a real tipping point.

AMOC in klimaatverandering
Why is your mother weak? This has to do with climate change. To understand why global warming is causing the AMOC to weaken, we need to take another look at how the AMOC works. At the surface, warm water is brought north from the equator. This water cools down all the way. In addition, more water evaporates along the way than fresh water is added to it, which increases the salt concentration. The further north you go, the colder and saltier the water will be. But the water also becomes heavier due to the salt and cooling. This causes it to sink to the north, after which it is pumped back to the equator. There it heats up again and the story begins again. But because of global warming, we are seeing big changes in the Arctic, especially in Greenland. The thick ice sheet on Earth here melts, releasing a huge amount of (fresh!) Fresh water mixes with salt water, making it less salty and therefore less heavy. This water easily sinks to the depth and thus weakens the AMOC.

fresh water flow
In short, the fact that we are currently heading towards a tipping point has to do with the flow of fresh water through the melting of the Greenland ice sheets, the melting of sea ice and increased precipitation and river drainage. “However, I did not expect that the increased amounts of fresh water added over the last century would have such an effect on oblique circulation,” Brewers says.

The consequences can be dire. If the AMOC loses more stability or even reaches a complete standstill, this will have far-reaching consequences for large parts of the world. For example, it could get colder in Europe. But there will also be consequences outside Europe. The heat that no longer comes to us, lingers in the south. And there may be hypertrophy in warming. However, the real consequences cannot yet be foreseen. “We urgently need to reconcile our models with the observational evidence provided to assess how close or really how close the AMOC is to the critical threshold,” Brewers concludes.