The global ocean conveyor system

The global ocean conveyor belt system, also known as the thermohaline circulation, is a complex network of ocean currents that play a crucial role in regulating the Earth’s climate. This natural phenomenon transports heat, nutrients and dissolved gases across the world’s oceans, influencing weather patterns and marine ecosystems.

What is the Global Ocean Conveyor Belt?

Definition and Mechanism

The global ocean conveyor belt is a system of deep and surface currents that connect the Atlantic, Indian, Pacific and Arctic oceans. This system is driven by differences in the temperature (thermo) and salinity (haline) of seawater, which affect its density. Denser water, which is cold and salty, tends to sink while warmer, less salty water rises, creating a continuous motion.

Key Components

1. Gulf Stream: It carries warm water from the Gulf of Mexico to the North Atlantic, warming western Europe.
2. North Atlantic Drift Current: Continuation of the Gulf Stream, which continues northeastward.
3. Sinking in the North Atlantic: Cold, salty water sinks into the high latitudes of the North Atlantic, forming deep currents.
4. Circulation in the Antarctic Ocean: The deep water moves southwards, where it mixes with Antarctic waters before being redistributed to other oceans.

(Photo: Robert Simmon, NASA)

Importance of Conveyor Belt System

Climate Regulation

The global ocean conveyor belt system plays a crucial role in regulating global climate by redistributing heat between oceans and land regions. For example, the Gulf Stream is responsible for maintaining a warmer climate in Western Europe, despite its high latitude. Without this circulation, temperatures in Europe would be significantly colder.

Nutrient Cycle

The conveyor belt also facilitates nutrient cycling in the oceans. Deep currents transport nutrients from the depths to the surface, where they can be used by marine organisms such as phytoplankton, the base of the ocean food chain. This process is essential to maintaining biological productivity and biodiversity in the oceans.

Carbon Absorption

Oceans act as carbon sinks, absorbing carbon dioxide (CO2) from the atmosphere. Thermohaline circulation helps distribute and store this carbon in the deep ocean, playing a vital role in regulating atmospheric CO2 levels and thus mitigating climate change.

Impact of Climate Change on the Conveyor Belt

Circulation disorders

Climate change is affecting the ocean conveyor belt in a number of ways. Rising global temperatures and melting glaciers are altering the salinity and temperature of seawater. This can weaken the thermohaline circulation, especially in the North Atlantic, where sinking cold, salty water is crucial to driving the system.

Climate consequences

A weakening or collapse of the conveyor belt could have serious climatic consequences. Western Europe could experience much colder winters, while other regions could face changes in rainfall and extreme weather patterns. In addition, a reduction in CO2 absorption by the oceans could accelerate global warming.

Impact on Marine Ecosystems

Changes in ocean circulation would also affect marine ecosystems. Altered nutrient supply could decrease biological productivity and affect marine species populations. This would have repercussions throughout the food chain and could impact fisheries and human food security.