What do understand by Atlantic Meridional Overturning Current? Explain in detail its relations with warming up of Indian Ocean.

Since the past 15 years, Atlantic Meridional overturning circulation (AMOC) has been weakening; a
development that could have dramatic consequences for Europe and other parts of the Atlantic
rim. Along with which Warming up of Indian Ocean is said to be a key driver.
How Atlantic Meridional Overturning Current affects?
Warming in the Indian Ocean generates additional precipitation, which, in turn, draws more air from
other parts of the world, including the Atlantic. The higher level of precipitation in the Indian Ocean
will reduce precipitation in the Atlantic and increase salinity in the waters.
What is the Atlantic Meridional Overturning Circulation?
 Atlantic Meridional overturning circulation (AMOC) — which is sometimes referred to as the
“Atlantic conveyor belt” — is one of the Earth’s largest water circulation systems where ocean
currents move warm, salty water from the tropics to regions further north, such as western
Europe and sends colder water south.
 As warm water flows northwards in the Atlantic, it cools, while evaporation increases its salt
content.
 Low temperature and high salt content increases the density of the water, causing it to sink deep
into the ocean.
 The cold, dense water deep below slowly spreads southward.
 Eventually, it gets pulled back to the surface and warms again, and the circulation is complete.
 This continual mixing of the oceans and the distribution of heat and energy around the planet
contributes to the global climate.
 Atlantic Meridional Overturning Current (AMOC) ensures the oceans are continually mixed, and
heat and energy are distributed around Earth.

How does the AMOC work?
 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.
 As warm water flows northwards it cools and some evaporation occurs, which increases the
amount of salt. Low temperature and a high salt content make the water denser, and this dense
water sinks deep into the ocean.
 The cold, dense water slowly spreads southwards, several kilometres below the surface.
Eventually, it gets pulled back to the surface and warms in a process called “upwelling” and the
circulation is complete.
Link between Atlantic Meridional Overturning Circulation (AMOC) and the Indian Ocean:
 For thousands of years, Atlantic Meridional Overturning Circulation (AMOC) has remained stable
but in the last 15 years, signs show that AMOC may be slowing, which could have drastic
consequences on the global climate.
 However, the rising temperatures in the Indian Ocean can help to boost the AMOC and delay
slow down.
 Warming in the Indian Ocean generates additional precipitation, which, in turn, draws more air
from other parts of the world, including the Atlantic.
 With so much precipitation in the Indian Ocean, there will be less precipitation in the Atlantic
Ocean.
 Lesser precipitation leads to higher salinity in the waters of the tropical portion of the Atlantic —
because there won’t be as much rainwater to dilute it.
 This saltier water in the Atlantic, as it comes north via AMOC, will get cold much quicker than
usual and sink faster.
 The above process would act as a jump start for AMOC, intensifying the circulation.
 But if other tropical ocean’s warming, especially the Pacific's, catches up with the Indian Ocean,
the advantage of intensification for AMOC may stop.
 Moreover, it isn't clear whether the slowdown of AMOC is caused by global warming alone or it
is a short-term anomaly related to natural ocean variability.
 Slowdown of AMOC had taken place 15,000 to 17,000 years ago which caused harsh winters in
Europe, with more storms or a drier Sahel in Africa due to the downward shift of the tropical
rain belt.
Alternating oceanic system patterns like ENSO also affects rainfall distribution in the tropics and can
have a strong influence on weather in other parts of the world.