09/19/2026
Atlantic currents are regulating Earth’s temperature.
New research suggests a major ocean circulation system acts like a “heat valve.” When it weakens, the ocean can retain more heat, with consequences for the planet’s energy balance.
The system is the Atlantic Meridional Overturning Circulation, or AMOC. It carries warm water northward near the surface and returns colder water southward at depth.
To understand its role, researchers looked back to the ice ages, when the circulation repeatedly shifted between stronger and weaker states.
Their study, published in Nature Geoscience, analyzed simulations from three climate models that reproduce these abrupt shifts under glacial conditions.
When circulation was strong, deep mixing in the North Atlantic helped release large amounts of ocean heat into the atmosphere. Changes in Earth’s radiation balance also allowed the planet to lose energy to space.
When circulation weakened, that deep mixing shut down. Less heat escaped from the North Atlantic while other ocean regions continued absorbing it. Heat accumulated underwater, and the planet gained energy overall.
The researchers describe this as opening and closing an ocean heat valve.
It also helps explain a puzzle in ancient ice cores: Greenland’s temperatures changed rapidly, while Antarctica’s shifted more slowly. Greenland responded to changes in nearby heat release; Antarctica tracked slower changes in ocean heat storage.
The implication is that future AMOC weakening could amplify planetary warming.
But this is not a prediction of an imminent collapse.
The simulations represent ice-age conditions, when extensive sea ice played a central role. A warmer, less icy Atlantic may behave differently.
The study offers evidence that Atlantic circulation can influence both where heat travels and how much Earth retains. How strongly that mechanism will operate in our future climate remains an open question.
Read the study:
"Planetary energy budget during abrupt glacial climate events set by Atlantic Ocean heat valve." Nature Geoscience