Atlantic Meridional Overturning Circulation (AMOC) ( UPSC Prelims)

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News Context

A scientific study reconstructing 12,000 years of the Atlantic Meridional Overturning Circulation (AMOC) during the Holocene Epoch revealed that, after being mostly stable with natural fluctuations throughout much of this time, the modern AMOC is now experiencing an unprecedented weakening.

AMOC

A network of ocean currents circulates water within the Atlantic Ocean, transporting warm water north and cold water south.
  ● Driving Force: Variations in water temperature and salinity.  
    ● Warm tropical water travels towards the poles, cools, becomes dense, sinks in the North Atlantic, and flows southward before warming and resurfacing, thereby restarting the cycle.  
  ● Significance:  
        ○ Affects rainfall patterns, including the Indian monsoon.
        ○ Facilitates heat transport from the tropics to higher latitudes, which helps moderate Europe’s climate.
        ○ Moves dense and carbon-rich water masses from the surface to the deep ocean.
  ● Concerns: There is a potential for the AMOC to slow down due to an increased influx of freshwater from the melting Greenland ice sheet and Arctic amplification caused by global warming.  

Potential Impacts of AMOC Slowdown

• AMOC carbon feedback: A decrease in the ocean's ability to absorb carbon, resulting in increased atmospheric CO2 and global warming.
 • Extreme events: For instance, colder temperatures in Europe, potential shifts in South Africa’s rain belt (causing droughts), and sea level rise (such as along the U.S. East Coast).
 • Fewer nutrients transport: This could impact various forms of sea life, including plankton, sea birds, fish, and whales.