The Atlantic Ocean is home to a powerful system of connected currents known as the Atlantic Meridional Overturning Circulation (AMOC).
This system plays a crucial role in regulating Earth’s climate by moving heat, moisture, and nutrients around the globe.
However, scientists have long worried that climate change and melting polar ice could disrupt or even collapse the AMOC, leading to disastrous consequences for the planet.
While predicting the AMOC’s future remains uncertain, a new study provides some reassuring news about its recent past.
Researchers from the Woods Hole Oceanographic Institution (WHOI) and their collaborators have found that the AMOC has not shown signs of weakening over the past 60 years.
Their findings, published in Nature Communications, suggest that the AMOC is currently more stable than many had feared.
“Our research shows that the AMOC has not declined yet,” said Nicholas P. Foukal, an adjunct scientist at WHOI and assistant professor at the University of Georgia.
“This doesn’t tell us what will happen in the future, but it does mean the changes we were concerned about haven’t occurred yet.”
A fresh look at AMOC’s stability
Previous studies, including a well-known 2018 paper, suggested that the AMOC had been weakening over the past 70 years.
These earlier studies relied on sea surface temperature data to estimate changes in the AMOC. However, according to the researchers, this method has limitations and may not accurately reflect the AMOC’s behavior.
To address these uncertainties, the team used a new approach. They relied on data from the Coupled Model Intercomparison Project (CMIP), which includes advanced climate models created by the World Climate Research Program. Instead of focusing on surface temperatures, the researchers looked at air-sea heat fluxes, which measure the exchange of heat between the ocean and the atmosphere. When the AMOC is stronger, more heat is released from the ocean into the atmosphere over the North Atlantic.
Using these heat fluxes as a proxy for the AMOC, the team analyzed reanalysis data—datasets that combine direct observations with model simulations. This allowed them to reconstruct the AMOC’s behavior from 1963 to 2017. Their findings showed that the AMOC has remained steady over this period, suggesting it is more stable than previously thought.
What does this mean for the future?
The study’s results indicate that the AMOC may not be as close to a critical tipping point as once feared. “Based on the results, the AMOC is more stable than we thought,” said Linus Vogt, one of the study’s authors. “This might mean there is more time to act before the system reaches a dangerous collapse.”
However, the researchers caution that their findings do not mean the AMOC is safe indefinitely. Climate models almost unanimously predict that the AMOC will slow down in the future as global temperatures continue to rise. Whether it will eventually collapse remains uncertain.
“This work gives us hope,” said Foukal. “It shows there is still time to take action and prevent the AMOC from reaching a tipping point. But we must act quickly to limit the impacts of climate change.”
While this study offers a more optimistic view of the AMOC’s current state, it also highlights the importance of reducing greenhouse gas emissions to protect Earth’s critical climate systems.
