Atlantic Meridional Overturning Circulation (AMOC)


  • Recently, a study published in Nature Climate Change notes that the Atlantic Meridional Overturning Circulation (AMOC), is losing its stability.

  • According to the IPCC’s Report (AR6) released on August 9, it is very likely that AMOC will decline over the 21st century.

What is Atlantic Meridional Overturning Circulation?

  • The AMOC is a large system of ocean currents.
  • It is the Atlantic branch of the ocean conveyor belt or Thermohaline circulation (THC), and distributes heat and nutrients throughout the world’s ocean basins.

    Atlantic Meridional Overturning Circulation
    Source: Wikipedia
  • AMOC carries warm surface waters from the tropics towards the Northern Hemisphere, where it cools and sinks. It then returns to the tropics and then to the South Atlantic as a bottom current.
  • From there it is distributed to all ocean basins via the Antarctic circumpolar current.

What happens if Atlantic Meridional Overturning Circulation collapses?

  • Gulf Stream, a part of the AMOC, is a warm current responsible for mild climate at the Eastern coast of North America as well as Europe.
  • Without a proper AMOC and Gulf Stream, Europe will be very cold.
  • Modelling studies have shown that an AMOC shutdown would cool the northern hemisphere and decrease rainfall over Europe. It can also have an effect on the El Nino.
  • AMOC collapse brings about large, markedly different climate responses: a prominent cooling over the northern North Atlantic and neighbouring areas, sea ice increases over the Greenland-Iceland-Norwegian seas and to the south of Greenland, and a significant southward rain-belt migration over the tropical Atlantic.
  • AMOC and THC strength has always been fluctuating, mainly if you look at the late Pleistocene time period (last 1 million years).
  • The extreme glacial stages have seen weaker circulation and slowdown in AMOC, while the glacial terminations have shown a stronger AMOC and circulation.

Source: Indian Express

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