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What is the Atlantic Meridional Overturning Circulation (AMOC)?

GS Paper 1

Topics Covered: Important Geophysical phenomena



According to a recent study, the Atlantic Ocean’s current system-AMOC, an engine of the Northern Hemisphere’s climate, could be weakening to such an extent that it could soon bring big changes to the world’s weather.

  • Climate models have shown that the AMOC is at its weakest in more than a 1,000 years.
  • However, it has not been known whether the weakening is due to a change in circulation or it is to do with the loss of stability.


What is the Atlantic Meridional Overturning Circulation (AMOC)?

The Atlantic Meridional Overturning Circulation (AMOC) is a large system of ocean currents that carry warm water from the tropics northwards into the North Atlantic.


How does the AMOC work?

  1. The AMOC is a large system of ocean currents, like a conveyor belt, driven by differences in temperature and salt content – the water’s density.
  2. As warm water flows northwards it cools and some evaporation occurs, which increases the amount of salt.
  3. Low temperature and a high salt content make the water denser, and this dense water sinks deep into the ocean.
  4. The cold, dense water slowly spreads southwards, several kilometres below the surface.
  5. Eventually, it gets pulled back to the surface and warms in a process called “upwelling” and the circulation is complete.


What if the AMOC collapsed?

If the AMOC collapsed, it would increase cooling of the Northern Hemisphere, sea level rise in the Atlantic, an overall fall in precipitation over Europe and North America and a shift in monsoons in South America and Africa.



Prelims Link:

  1. About AMOC.
  2. What are Ocean Currents.
  3. Important ones.
  4. Causes.
  5. Effects.

Mains Link:

Discuss the impact of weakening AMOC.

Sources: the Hindu.