AMOC slowing – New buoy-based analysis finds the AMOC weakening at four western Atlantic latitudes, strengthening evidence that Europe’s ocean-driven climate may be shifting.
The Atlantic Meridional Overturning Circulation. or AMOC. is the ocean’s long-distance heat engine—and new observations suggest it’s losing strength.. nnNew evidence from buoy measurements points to a key ocean current slowing at multiple locations across the western Atlantic.. For scientists. the update is important because it helps move the debate from tentative hints toward a more coherent. directly observed pattern: the system that warms western Europe may be weakening in a way that could have
outsized climate consequences.. nnAt the heart of the AMOC is a familiar idea in ocean science: water doesn’t just drift. it travels.. Warm. salty water moves north from the Gulf of Mexico. releasing heat to the atmosphere as it travels toward higher latitudes.. Eventually. the water cools and becomes denser. sinking and then returning south along the seafloor along the Atlantic’s western side.. That “conveyor belt” moderates winter conditions for parts of western Europe—making it
milder than in regions at similar latitudes in Canada or Russia.. nnFor decades. researchers have known that the AMOC can fluctuate naturally. making it difficult to separate short-term variability from a long-term trend.. Indirect reconstructions using older temperature records have suggested the AMOC has weakened by roughly 15% since 1950. and some climate modeling studies have warned that the circulation could slow toward shutdown on timescales of decades.. But direct measurements are comparatively recent. spanning
only about two decades in the most continuous form—so confidence has often been tempered by the question of whether the observed behavior is stable or just a temporary dip.. nnA new study led by Qianjiang Xing at the University of Miami strengthens the case for a persistent slowdown by drawing on a widely used observational system: RAPID-MOCHA. an array of anchored moorings installed in 2004 stretching from the Bahamas to the Canary Islands.. The array
collects data on temperature. salinity. and velocity. allowing scientists to estimate “pressure” as a proxy for how much water is effectively stacked up. and therefore how strongly water should flow through the overturning circulation.. In simple terms. water tends to move from higher pressure toward lower pressure. and the Earth’s rotation helps steer that movement into a large-scale pattern that powers the AMOC.. nnMisryoum describes the analysis as a careful effort to verify the signal
rather than just report it.. The study finds that the AMOC flow is declining by about 90. 000 cubic meters of water per second each year—faster than what had previously been observed in the same system.. Over the period from 2004 to 2023. that rate translates into a weakening of around 10%. though the authors stress that uncertainty remains substantial.. What changes the strength of the finding is the way the research team checks the
result against other mooring arrays installed after 2004—off the West Indies. along the U.S.. east coast, and off Nova Scotia, Canada—to look for consistency across space, not just at one measurement line.. nnThe deeper implication is not only that the AMOC may be weakening. but that the weakening appears in a “coherent picture” across multiple latitudes in the western Atlantic.. Using data from four different latitudes. Misryoum reports that the pattern is consistent with weakening
at the western boundary. and that this matches expectations about what should happen if the circulation is being slowed by freshwater.. nnScientists suspect that melting from the Greenland ice sheet is increasing freshwater input into the North Atlantic.. Freshwater dilutes the dense, salty water that needs to sink to keep the overturning circulation running.. If the sinking water becomes less dense or sinks more slowly. the downstream southward flow along the seafloor weakens—exactly the kind
of deep western pattern the study’s interpretation points toward.. The researchers’ comparisons across mooring sites also reduce the chance that the signal is an anomaly confined to a single geographic slice of the ocean.. nnMisryoum readers might reasonably ask what happens if the slowdown continues.. A “collapse” or near-collapse of the AMOC would not mean the ocean stops moving; instead. the overturning would likely weaken dramatically enough to alter how heat is transported to the
atmosphere.. For Europe, that could translate into notably colder winters.. Beyond Europe. Misryoum notes that large-scale ocean changes can propagate into rainfall patterns. potentially disrupting monsoon systems across Asia and Africa.. The study’s authors frame their findings as compatible with a trajectory toward a tipping point—an uncomfortable phrase in climate science that refers to thresholds where gradual change could accelerate into a more abrupt shift.. nnStill, the most immediate takeaway is practical for the science
itself: more observing is needed.. The AMOC is complex and capable of natural swings. and even strong evidence benefits from longer time series and expanded coverage.. The study adds one of the strongest direct observational signals so far. but it also serves as a prompt for urgency—because understanding whether the AMOC is merely weakening or moving toward a qualitative change requires continued. high-quality measurements across the basin.