News: A new study finds that the Europe faces deep winter freeze if the Atlantic Meridional Overturning Circulation (AMOC) collapses.
About Atlantic Meridional Overturning Circulation (AMOC)
- The AMOC is a system of ocean currents that circulates water within the Atlantic Ocean, bringing warm water north and cold water south.
- Mechanism: The circulation process begins as warm water near the surface moves toward the poles (such as the Gulf Stream in the North Atlantic), where it cools and forms sea ice.
- As this ice forms, salt is left behind in the ocean water. Due to the large amount of salt in the water, it becomes denser, sinks down, and is carried southwards in the depths below.
- Eventually, the water gets pulled back up towards the surface and warms up in a process called upwelling, completing the cycle.
Importance of Atlantic Meridional Overturning Circulation (AMOC)
- AMOC aids in distributing heat and energy around the earth (heat budget).
- Western Europe’s climate is less harsh even in winters because of AMOC (Gulf Stream, North Atlantic Drift).
- It acts as a carbon sink by absorbing and storing atmospheric carbon.
Weakening of AMOC
- It takes an estimated 1,000 years for a parcel (any given cubic meter) of water to complete its journey along the belt.
- However, climate models suggest that the AMOC will weaken over the 21st Century as greenhouse gases increase.
- This is because as the atmosphere warms, the surface ocean beneath it retains more of its heat.
- Meanwhile increases in rainfall and ice melt mean it gets fresher too.
- All these changes make the ocean water lighter and so reduce the sinking in the ‘conveyor belt’, leading to a weaker AMOC.
Any substantial weakening of the AMOC would cause
- further decrease in marine productivity in the North Atlantic (less sinking will lead to less mixing of water),
- more storms in Northern Europe
- less Sahelian summer rainfall and South Asian summer rainfall
- a reduced number of tropical cyclones in the Atlantic
- an increase in regional sea level along the northeast coast of North America.
