The Ocean's Conveyor Belt — Global Circulation
Quick Fact
The ocean conveyor belt moves water around the entire planet in a cycle that takes approximately 1,000 years — and it keeps Western Europe up to 10°C warmer than it would otherwise be.
About This Species
The thermohaline circulation — often called the ocean conveyor belt — is a global system of ocean currents driven by differences in water temperature and salinity. It moves vast quantities of heat, nutrients, and carbon around the planet, regulating climate, supporting fisheries, and distributing oxygen to the deep ocean. The Atlantic Meridional Overturning Circulation (AMOC), the North Atlantic component of this system, keeps Western Europe significantly warmer than it would otherwise be. Climate scientists warn that melting Arctic ice is disrupting this system, with potentially catastrophic consequences for global climate patterns.
Why It Matters
Disruption of the ocean conveyor belt by climate change could trigger rapid and dramatic shifts in global climate patterns — including cooling of Western Europe, disruption of monsoon systems, and collapse of fisheries that depend on nutrient upwelling.
Transcript
The ocean conveyor belt is one of the most important systems on Earth. And we're in the process of breaking it. The technical name is thermohaline circulation — thermo for temperature, haline for salt. It's a global system of ocean currents driven by differences in the density of seawater. Cold, salty water is denser and sinks. Warm, fresh water is lighter and rises. This creates a continuous circulation that moves water — and with it, heat, nutrients, carbon, and oxygen — around the entire planet. The cycle takes approximately 1,000 years to complete. It's been running continuously for millions of years. The North Atlantic component — called the Atlantic Meridional Overturning Circulation, or AMOC — is particularly important for us in Europe. It carries warm tropical water northward, releasing heat into the atmosphere and keeping Western Europe up to 10 degrees Celsius warmer than it would otherwise be. Without it, Ireland and the UK would have a climate more like Labrador. Climate change is disrupting this system. Melting Arctic ice and Greenland glaciers are pouring vast quantities of fresh water into the North Atlantic. Fresh water is less dense than salt water. It doesn't sink. It disrupts the circulation. Scientists have detected a significant weakening of AMOC over the past century. Some models suggest it could collapse entirely within decades. The consequences would be severe — rapid cooling of Western Europe, disruption of monsoon systems across Africa and Asia, collapse of fisheries that depend on nutrient upwelling. The ocean regulates our climate. Destabilise it, and everything changes.