A critical ocean current system that helps regulate Earth’s climate has not declined over the past 60 years, according to new research that challenges previous warnings about its stability. The finding offers a rare piece of encouraging news in climate science, though researchers caution that future risks remain.
The study, published in Nature Communications by scientists from Woods Hole Oceanographic Institution (WHOI), examined the Atlantic Meridional Overturning Circulation (AMOC), a vast system of ocean currents that influences weather patterns across the globe.
Overturning Previous Findings
“Our paper says that the Atlantic overturning has not declined yet,” explains Nicholas P. Foukal, who conducted the research while at WHOI. “That doesn’t say anything about its future, but it doesn’t appear the anticipated changes have occurred yet.”
The findings directly contradict a widely cited 2018 study that had reported a significant weakening of the AMOC over the previous 70 years. The new research suggests that the methods used in that earlier study may have been flawed.
A New Approach to Measurement
The research team took a different approach to studying the AMOC’s strength. Rather than relying solely on sea surface temperature measurements, which “doesn’t work as well as initially thought,” according to Jens Terhaar, the team examined heat exchange between the ocean and atmosphere using 24 different climate models.
Global Weather Machine
The AMOC’s importance to global climate can hardly be overstated. Operating like a massive conveyor belt through the Atlantic Ocean, this current system is powered by winds and ocean density differences. It plays a crucial role in distributing heat, moisture, and nutrients throughout the world’s oceans, effectively helping to regulate Earth’s climate and weather patterns.
Time to Act
“It’s almost unanimous at this point that the Atlantic overturning will slow in the future, but whether or not it will collapse is still up for debate,” Foukal notes. “This work indicates that there is still time to act before we reach this potential tipping point.”
Stability with Caveats
“Based on the results, the AMOC is more stable than we thought,” adds Linus Vogt, one of the study’s authors. “This might mean that the AMOC isn’t as close to a tipping point as previously suggested.”
However, the researchers emphasize that their findings come with important limitations. Direct measurements of air-sea heat exchange from earlier decades are sparse, introducing significant uncertainty into their analysis. Despite these limitations, Terhaar concludes that “a decline in AMOC over the last 60 years seems very unlikely.”