Antarctic Ocean Circulation Slows Down Due To Melting Ice, With Global Consequences

Climate change is having a profound impact on the oceans, especially in the polar regions where ice sheets are melting and spilling freshwater into the sea.

This affects the circulation of waters in the deepest reaches of the ocean around Antarctica, which play a vital role in regulating the global climate and marine life.

What is happening and why does it matter?

(Photo : MIGUEL MEDINA/AFP via Getty Images)

The circulation of waters in the deep ocean is part of a global network of ocean currents that carry nutrients, oxygen, and carbon, as per Phys.org.

This process is also known as overturning circulation.

It involves cold, dense water sinking to the bottom of the ocean near Antarctica and then flowing northward, while warmer, lighter water rises to the surface and flows southward.

This circulation helps to transport heat from the tropics to the poles, and to store carbon dioxide and heat in the deep ocean.

The oceans absorb about a quarter of the human-caused carbon dioxide emissions and more than 90% of the excess heat trapped by greenhouse gases.

However, climate change is disrupting this balance. As the atmosphere warms, so does the surface of the ocean.

This reduces the density and salinity of the water, making it harder to sink.

At the same time, melting ice sheets add more freshwater to the ocean, further reducing its density and salinity.

This slows down the overturning circulation and reduces the ability of the oceans to absorb carbon dioxide and heat.

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How fast is it happening and what are the consequences?

A previous study using computer models predicted that the overturning circulation of waters in the deepest reaches of the ocean around Antarctica would slow by 40% by 2050 if emissions remain high, as per Yahoo News.

But a new study based on observational data found that this process had already slowed by 30% between the 1990s and 2010s. This means that the impacts of climate change are happening decades "ahead of schedule".

The implications could be significant for both the climate and marine life.

As ocean circulation slows, more carbon dioxide and heat are left in the atmosphere, creating a feedback loop that accelerates global warming.

This could lead to more extreme weather events, sea level rise, coastal erosion and flooding.

The slowing circulation also affects the oxygen levels in the deep ocean, which are essential for many marine animals.

The new study found that the oxygen reaching the deep ocean has decreased by about 10 percent since 1990.

This could force some deep-ocean animals to seek refuge in other regions or adapt their behavior.

It could also alter the food web and biodiversity in the ocean.

What can be done to prevent or mitigate it?

The only way to prevent or slow down the dangerous slowing of Antarctic ocean circulation is to reduce greenhouse gas emissions and limit global warming.

The authors of the new study said that their findings highlight "the urgency for immediate action on emissions reductions".

Some possible mitigation measures include enhancing ocean monitoring and observation systems, improving climate models and projections, increasing public awareness and education, supporting marine conservation and adaptation efforts, and promoting international cooperation and coordination on ocean issues.

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