Worrying message: major ocean currents are on the brink of a catastrophic tipping point

The impact on the vast areas of the planet affected by the circulation of the Atlantic meridian could be enormous, including climatic conditions, agricultural practices, biodiversity and economic stability, reports sciencealert.com.

At the heart of the problem is the rate of global warming and the melting of glaciers in the Arctic. According to the researchers’ new models, the temperature is rising so rapidly that the risk of reaching the point of transformation of the circulation of the Atlantic meridian, that is, the stop of the currents, is a cause for great concern.

“The news is worrying,” said physicist Johannes Lohmann of the University of Copenhagen in Denmark. “If the information in our analyzes is correct, human freedom of action is severely limited.”

Mr. Lohmann and his colleague Peter Ditlevsen adapted the current ocean climate change model to study the effects of increased freshwater flow in the North Atlantic Ocean due to the rapid melting of the Greenland ice sheet.

The model showed that a greater flow of fresh water could neutralize the circulation of the Atlantic meridian much earlier. In this scenario, the rate of change is more important than the specific thresholds. Once you hit the tipping point, there will be no turning back.

In other words, the amount of greenhouse gases emitted into the atmosphere and the rate at which Greenland’s glaciers are melting leave little room for action to protect climate-responsible climate systems around the world. This problem could also threaten other climate subsystems on our planet, scientists say.

“These transformation points have been represented in previous climate models that used to select for the slow flow of polarized water in the ocean,” Lohmann said. “However, the flows of water from the Greenland glaciers that are melting reality are increasing and cannot be considered slow.”

The circulation process of the Atlantic meridian is partly reminiscent of a giant closed-circle seawater transporter that distributes water and heat in the Northern Hemisphere with fluctuations in water temperature, salinity, and relative weight. It is one of the reasons why winters in Europe are relatively mild even at higher altitudes.

Although it is not clear exactly where the point of transformation of the circulation of the Atlantic meridian is, it has slowed down in recent years. According to the new study, the faster global warming, the greater the risk to ocean currents. Scientists speculate that the influx of cool fresh water from Greenland will likely prevent the warm water from spreading north.

Modeling climate change is an extremely complex process, as a large number of factors need to be taken into account. Mr. Lohmann and Mr. Ditlevsen acknowledged that there is still much work to be done to clarify the details of this disastrous scenario.

On the other hand, the scientists hope their model will become a kind of reminder of the importance of tackling climate change immediately. Our targets for reducing carbon emissions must be as ambitious as possible, whatever the situation in the North Atlantic. Perhaps we can no longer be wrong.

“Due to the chaotic dynamics of complex systems, the critical change of parameters is not clearly defined, so the possibility of predicting long-term qualitative changes is very limited,” the researchers point out in their work. “The results show that Earth’s climate-safe carbon footprint may be less than we previously thought.”
The study was published in the journal PNAS.