Oceanographers at the University of Miami say they have assembled some of the clearest direct evidence yet that the Atlantic Meridional Overturning Circulation, or AMOC — the vast system of currents that includes the Gulf Stream — has been steadily weakening for nearly two decades.
The research, from the university's Rosenstiel School of Marine, Atmospheric, and Earth Science, drew on seafloor-anchored instruments at four monitoring arrays stretching along the ocean's western edge, roughly between 16.5 and 42.5 degrees north latitude, measuring pressure, temperature and currents more than 1,000 meters deep. The consistent pattern across all four arrays, described by the university, suggests a genuine basin-wide shift rather than a temporary fluctuation tied to any single storm season or ocean cycle.
"A weaker AMOC can shift weather patterns, potentially leading to more extreme storms, changes in rainfall, or colder winters in some regions," said Shane Elipot, the study's senior author and a physical oceanographer at the Rosenstiel School. "It can also influence sea-level rise along coastlines."
The AMOC acts as a planetary conveyor belt, carrying warm surface water north and cold, dense water back south along the ocean floor. It is a key reason why Western Europe enjoys milder winters than other regions at similar latitudes, and its behavior influences hurricane formation and rainfall reliability across the tropics. The findings, published in the journal Science Advances and newly summarized by ScienceDaily this week, add to a growing body of research, including NASA-funded work, tracking the current's long-term trajectory.
Researchers are careful to distinguish a gradual weakening from an abrupt "collapse," a scenario popularized in disaster films but considered less likely in the near term by most climate scientists; other recent modeling suggests the pace of global warming, not just its eventual magnitude, determines whether the system can stabilize. Still, the two-decade trend adds urgency to monitoring efforts, with scientists saying continued observation from the same arrays will be essential to determine whether the slowdown accelerates in the years ahead.