Ocean Current Defies Doomsday Predictions, Stays Steady for 60 Years

Earth’s oceans, covering 71% of the planet’s surface, profoundly shape global climate and weather. At the heart of this system is the Atlantic Meridional Overturning Circulation (AMOC), a network of Atlantic currents driven by wind and ocean density differences. The AMOC redistributes heat, moisture, and nutrients worldwide, playing a critical role in regulating Earth’s climate.

As climate change accelerates, scientists worry that fresh water from melting polar ice sheets could disrupt—or even collapse—the AMOC. While a decline would have severe consequences, a collapse would be catastrophic. However, the future of this vital circulation remains uncertain. To explore its trajectory, researchers at the Woods Hole Oceanographic Institution (WHOI) turned to historical data for insights.

Findings on AMOC Stability

A new study published in Nature Communications reveals that the AMOC has remained stable over the past 60 years. Researchers Nicholas P. Foukal, Jens Terhaar, and Linus Vogt found no evidence of the decline suggested by earlier studies. “Our paper shows the Atlantic overturning hasn’t declined yet,” Foukal explained. “While this doesn’t predict the future, the anticipated changes haven’t happened so far.”

This conclusion challenges a 2018 study that reported a 70-year decline in the AMOC based on sea surface temperature (SST) data. However, Terhaar noted, “We’ve learned that SST isn’t as reliable for reconstructing the AMOC as once thought.”

Improved Data and Methods

To refine their analysis, the team used updated data from the Coupled Model Intercomparison Project (CMIP), a set of advanced climate models. They focused on air-sea heat fluxes—the heat exchange between the ocean and atmosphere—as a more reliable indicator of AMOC strength. When the AMOC is stronger, more heat is released into the atmosphere over the North Atlantic.

The researchers applied their model to reanalysis data sets extending back to the late 1950s, similar to how weather forecasts incorporate observations. Their results indicate that the AMOC has shown no weakening from 1963 to 2017. “This suggests the AMOC may not be as close to a tipping point as previously feared,” Vogt explained.

Implications and Uncertainties

The study underscores the AMOC’s resilience and offers a hopeful outlook, suggesting more time to address potential tipping points. “While most agree the AMOC will likely slow in the future, whether it collapses is still uncertain,” Foukal noted.

However, the findings come with limitations. Direct measurements of air-sea heat fluxes over time are sparse, and reanalysis data contain uncertainties. Despite these challenges, Terhaar emphasized, “A significant decline in the AMOC over the last 60 years seems very unlikely.”

This research provides valuable insight into the AMOC’s stability while reinforcing the urgency of mitigating climate change to safeguard Earth’s vital systems.

Read Original Article: Scitechdaily

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