Climate scientists disagree sharply over whether the Atlantic Meridional Overturning Circulation is nearing a collapse. A recent study claims a subsurface temperature fingerprint signals decades of decline that could alter European winters, while other researchers warn against apocalyptic predictions and emphasize the brevity of ocean observation series.
The Atlantic Meridional Overturning Circulation functions as an expansive conveyor belt of the ocean, carrying warm surface water north from the tropics toward the Northern Hemisphere before it cools, sinks, and returns south along the ocean floor. This vital system includes the Gulf Stream, which flows from the Gulf of Mexico up the United States East Coast and across the Atlantic toward Europe, helping to maintain mild climates across Europe, the United Kingdom, and the eastern United States.
Controversial Findings Point to Decades-Long Slowdown
A study published in the journal Communications Earth & Environment by researchers from the Institute of Oceanology of the Chinese Academy of Sciences and the University of California, San Diego, argues that climate change could push the AMOC to the brink of collapse within decades. According to the new study, thawing temperatures are causing Greenland Ice Sheet meltwater to leach into the North Atlantic, leading to stagnation.
The research team utilized the Massachusetts Institute of Technology General Circulation Model to simulate ocean and climate dynamics. They observed how energy waves travel along the western North Atlantic toward the equator, creating an oceanic hot spot at intermediate depths.
Study authors, Communications Earth & Environment stated that they identified a distinctive temperature fingerprint in the equatorial Atlantic signaling changes in the Atlantic Meridional Overturning Circulation, adding that its robust physical mechanism and reliable detection make the fingerprint a valuable metric for monitoring the AMOC in a warming climate.
By examining observational data dating back to 1960, the investigators found that mid-depth warming spiked in the late 2000s, suggesting that the current’s decline started during the late 20th century. Jonathan Bamber, a professor of Earth observation at the University of Bristol, told reporting outlets that a major slowdown could carry severe consequences.
Oceanographers Highlight Data Gaps and Natural Variability
Other oceanographers urge caution regarding catastrophic forecasts. Léon Chafik, an oceanographer and climate researcher at Stockholm University, notes that while global climate impacts from an AMOC weakening are widely accepted, predicting the timing and rate of change remains exceptionally difficult.
Researchers also differ on foundational definitions, including how the circulation is modeled mathematically and whether observations focus on high or low latitudes.
Furthermore, observational records remain brief. Continuous measurements began in 2004 from the Florida coast to northwest Africa, followed in 2014 by a monitoring program stretching across the North Atlantic between Canada and Scotland. Instruments placed between Greenland, Iceland, the Faroe Islands, and Scotland since the mid-1990s show that inflowing water toward Norway and the Arctic has warmed, but they do not show a decrease in total volume.
Chafik points out that natural climate cycles can span 30 to 50 years or longer, making it challenging to separate long-term weakening from natural ocean fluctuations using short observation windows.
Funding Pressures Threaten Ongoing Ocean Observations
To secure better data, Nordic researchers have pushed for long-term financing at both ministerial and European Union levels to keep critical monitoring instruments operational. However, short funding cycles and potential interruptions present persistent obstacles.
Those monitoring efforts faced fresh disruption when the Trump administration announced plans to phase out several ocean observatories within the Ocean Observatories Initiative, leading to the retrieval of instruments and stations. Because the United States handles roughly half of global ocean surveillance, scaling back these networks creates a significant hurdle for researchers attempting to track global circulation patterns.
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