AMOC
Atlantic Meridional Overturning Circulation: a system of currents that transports warm water northward and cold water southward in the Atlantic Ocean.
The AMOC (Atlantic Meridional Overturning Circulation) is the Atlantic component of the global thermohaline circulation and one of the planet's most important climate systems. It consists of a flow of warm surface water travelling from the tropics to the North Atlantic (including the Gulf Stream and North Atlantic Drift), where it cools, sinks to depths of 2,000–4,000 metres, and returns southward as a deep current.
The AMOC transports approximately 1.3 petawatts (1.3 × 10¹⁵ watts) of thermal energy northward, which explains why cities like London (51°N) have much milder winters than Montreal (45°N). Without this heat transport, average temperatures in western Europe would be 5–10 °C lower. Additionally, the AMOC drives oceanic CO₂ absorption by sinking surface water rich in dissolved carbon and transports nutrients sustaining Atlantic marine ecosystems.
Measurements from the RAPID programme (since 2004) have documented considerable variability and a weakening trend. The Intergovernmental Panel on Climate Change (IPCC) projects the AMOC will weaken by 25–50% by the end of the 21st century under high-emission scenarios. Some studies suggest it could reach a tipping point, triggering abrupt European cooling, disruption of hemispheric precipitation patterns, and accelerated sea level rise along America's eastern coast.