A major ocean current system in the Atlantic could collapse as early as 2025, according to new peer-reviewed research. This is particularly worrying in light of the current extreme temperatures we are seeing around the world, including a significant deviation from previous records in the Atlantic Ocean.

“Here we calculate that early warning signs significantly exceed natural fluctuations,” said physicist Peter Ditlevsen and statistician Suzanne Ditlevsen of the University of Copenhagen. “Given the importance of AMOC for the climate system, we should not ignore such clear signs of an imminent collapse.”

The Atlantic Meridional Overturning Circulation (AMOC) is a major ocean current system that includes the well-known Gulf Stream and regulates the transfer of ocean heat from the tropics to the Northern Hemisphere.

Thus, it significantly affects the Earth’s climate. It’s considered one of the major disruptors of Earth’s climate system and has been slowing down since the mid-1900s. If it stops completely, monsoon seasons in the tropics could be interrupted, and winters in Europe and North America will be dangerously harsh. The knock-on effects will severely impact entire ecosystems and our food security.

AMOC has only been directly tracked since 2004, which isn’t long enough to understand the full course of the current slowdown trend.

Therefore, after examining several models, the researchers identified the region of the ocean where sea surface temperatures are closest to ocean circulation conditions, to use as one of the less direct indicators for which there are records dating back to 1870.

Another early warning sign the researchers believed was a “loss of stability” in the system; this manifests itself as increased oscillation and dispersion, such as an increase in spindle wobble before tipping over.

Using these two early warning signs to assess the status of AMOC is similar to measuring heart rate and blood pressure to monitor the condition of the heart. The team’s modeling shows that this crucial ocean circulation could stop as early as 2025 and possibly as late as 2095.

Peter Ditlevsen and Suzanne Ditlevsen say these findings are considerably earlier than the IPCC’s latest estimates, but early signs are already evident. The team noted in the paper that “previous models are biased to overestimate AMOC stability, both from setting to historical climate records and poorly representing deep water formation, salinity, and glacial current.”

Also, the rate at which we reach this destabilizing event can determine whether the system crashes or returns to a steady state. As we have failed to reduce the amount of greenhouse gases we emit into the atmosphere, but instead increase it, it seems that we are on a dire trajectory to reach the ocean threshold hard and fast.

Past studies have shown that previous climate extremes or Dansgaard-Eschger events were caused by such instabilities. Previous research has shown that a change in a single parameter, such as an increase in the amount of freshwater entering the North Atlantic, can cause a bifurcation of the system and lead to a sudden and dramatic change in the behavior of the system.

This level of sensitivity may not have been met in the IPCC assessment because not all models they included take it into account. We still don’t understand all the factors that could affect this system, and other researchers say factors such as the effect of cold water flows don’t quite match the past climate record.

The researchers believe that their method, which focuses on early warning symptoms, eliminates the need to fully understand these drivers, but they also note that they cannot rule out that some unknown unknowns may lead to a different outcome. They also explain that they cannot distinguish between partial or complete collapse of AMOC.

“Despite these warnings, this is a truly alarming result that should call for swift and effective action to reduce global greenhouse gas emissions to prevent a permanent shift in the control parameter towards AMOC collapse,” the team said. Source