Atlantic Meridional Overturning Circulation (AMOC)

node · earth · Atlantic Ocean

The Atlantic limb of the density-driven circulation: warm, salty water moving north near the surface, losing heat to the atmosphere at high latitudes, sinking, and returning south at depth as North Atlantic Deep Water. It is the best-observed overturning cell on Earth because a single mooring array has watched it continuously at one latitude for over twenty years. Across April 2004 to January 2023 the RAPID array at 26.5°N gives a mean overturning maximum of 17.0 Sv with a standard deviation of 2.8 Sv, and a weakening trend of 1.0 [0.4–1.6] Sv per decade. That trend is small against the variability, which is why the argument about whether the AMOC is declining is an argument about signal and noise as much as about physics.