How a shift in the Gulf Stream could signal the collapse of a major ocean current system - Earth - Earth Sciences - Environment

Horizontal velocities responses. Credit: Communications Earth & Environment (2026). DOI: 10.1038/s43247-026-03309-1

Changes in the Gulf Stream, a strong ocean current in the Atlantic, could serve as an early warning of the imminent collapse of the Atlantic Meridional Overturning Circulation (AMOC). The AMOC is a massive system of ocean currents that acts as a conveyor belt, moving heat from the tropics to the North Atlantic. The part of this system that flows along the east coast of the United States and then east toward Europe is the Gulf Stream. Scientists are concerned that if the AMOC were to collapse, it could trigger drastic climate shifts, especially in Europe, where temperatures could plummet.

Modeling the collapse

To better understand how the AMOC and the Gulf Stream are linked, researchers at the Institute for Marine and Atmospheric Research at Utrecht University in the Netherlands modeled what would happen if the AMOC collapsed. They describe their work in a paper published in the journal Communications Earth & Environment.

The researchers used a high-resolution ocean simulation, which allowed them to see fine details of the ocean's circulation. They slowly added freshwater to the model's North Atlantic area to simulate melting ice sheets. This dilutes the ocean's saltiness and eventually slows and stops the AMOC conveyor belt.

As it slows down, the Gulf Stream reaches a breaking point and suddenly jumps 219 km (136 miles) north in just two years. This shift occurred approximately 25 years before the AMOC collapsed in the simulation, suggesting it could serve as a warning signal in the real world.

To see if any warning signs were already appearing, the team compared their model's behavior with satellite data from the last 30 years and deep-sea records dating back to 1965.

Gulf Stream path in observations. Credit: Communications Earth & Environment (2026). DOI: 10.1038/s43247-026-03309-1

Red flags

They identified several red flags in both the real-world data and the model. The most significant is that the Gulf Stream has already begun to drift northward from the coast near Cape Hatteras, North Carolina. This northward shift is exactly what happened in the simulation just before the circulation failed.

Because the Gulf Stream is moving farther north than usual, the waters in these areas are warming faster, as reflected in deep-sea records.

The Deep Western Boundary Current, which flows beneath the Gulf Stream, is also weakening in both the observed data and the simulation.

"These findings provide indirect evidence for present-day AMOC weakening and demonstrate that abrupt Gulf Stream shifts can serve as an early warning indicator for AMOC tipping," commented the study authors in their paper.

While the collapse of the AMOC may not yet be inevitable, these findings suggest it is weakening and may approach a tipping point faster than previously thought. 

by Paul Arnold, Phys.org

edited by Gaby Clark, reviewed by Robert Egan 

Source: How a shift in the Gulf Stream could signal the collapse of a major ocean current system