Description

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Context

A study highlights weakening of Antarctic Circumpolar Current one of most powerful ocean currents due to ice sheet melting leading to concerns about climate variability, global warming & ecosystem disruption.

Key Highlights

The study reveals that Antarctic Circumpolar Current (ACC) is slowing down due to melting ice sheets with predicted 20% reduction in its strength by 2050.

ACC plays crucial role in regulating Earth climate by distributing heat, water & nutrients. A slowdown could lead to increased climate variability & extreme weather events.

As ACC weakens ocean ability to act as carbon sink will decrease accelerating global warming.

ACC also acts as natural barrier to non native marine species. Its slowdown could allow species like bull kelp, shrimp, mollusks to invade Antarctica disrupting local food web & threatening native species like penguins.

Researchers used high-resolution ocean & sea ice simulations on Australia fastest supercomputer GADI to study future behavior of ACC focusing on ocean currents, heat movement & salinity changes.

Melting ice sheets add fresh water to the ocean altering salinity & disrupting current flow. The study stresses importance of reducing carbon emissions to slow global warming & limit ACC slowdown.

Previous studies suggested the ACC might speed up due to increasing temperature differences but this new study presents mechanism for its projected slowdown highlighting need for further research in the region.

The study predicts that transport of ocean water from surface to the deep ocean could also slow in the future with wide-ranging implications for global climate systems.

Researchers stress importance of limiting global warming to prevent further ice melting in Antarctica urging concerted efforts to reduce carbon emissions in line with Paris Agreement.

Antarctic Circumpolar Current (ACC)

Aspect	Details
Name	Antarctic Circumpolar Current (ACC)
Location	Southern Ocean, circling Antarctica, connecting the Atlantic, Pacific, and Indian Oceans
Strength	Five times stronger than the Gulf Stream and over 100 times more powerful than the Amazon River
Role	Regulates global climate by distributing heat, water, and nutrients Acts as a natural barrier, preventing non-native species from reaching Antarctica
Impact on Climate	Regulates heat and water distribution Acts as a carbon sink, absorbing CO2 and mitigating global warming
Effect of Melting Ice Sheets	Introduction of fresh water into the ocean alters salinity and disrupts the flow of the current Weakening could lead to increased climate variability, extreme weather events, and reduced oceanic CO2 absorption
Predicted Slowdown	Projected to slow down by 20% by 2050 due to melting ice and changes in ocean salinity
Key Threats	Potential disruption of the Antarctic food web (e.g., native species like penguins could be threatened) Risk of invasive species reaching Antarctica (e.g., bull kelp, shrimp, mollusks)

Main Antarctic Ocean Currents

Current	Description
Antarctic Circumpolar Current (ACC)	The world’s strongest and most powerful ocean current, flowing eastward around Antarctica. It connects the Atlantic, Pacific, and Indian Oceans, playing a crucial role in regulating climate by distributing heat, water, and nutrients.
West Wind Drift	This current is part of the ACC, flowing from west to east, moving warm waters away from Antarctica and helping maintain the cold temperature of the Southern Ocean.
East Wind Drift	A slower-moving current in the Southern Ocean, flowing from east to west, opposite to the ACC, influencing the movement of cold waters and impacting sea ice dynamics.
Benguela Current	A cold, nutrient-rich ocean current that flows northward along the west coast of the Southern Ocean, contributing to the upwelling of deep, cold water.
Antarctic Coastal Current	This current flows along the Antarctic coast, transporting cold, dense water away from the continent into the Southern Ocean.
Weddell Gyre	A large ocean gyre formed by the movement of the Antarctic Circumpolar Current, which contributes to the upwelling of cold, dense water around the Weddell Sea, influencing the formation of sea ice.
Ross Gyre	Another significant ocean gyre driven by the ACC, located in the Ross Sea, contributing to the mixing of waters and influencing the distribution of sea ice and nutrients in the region.
Antarctic Divergence	A zone where surface waters from the Antarctic Convergence move away from each other, leading to upwelling and nutrient-rich waters.

For more specifics on the currents, please refer to IAS GYAN & IAS GYAN 2

Sources:

NEWS18

PRACTICE QUESTION

Q. Which of following statements about Antarctic Circumpolar Current (ACC) is/are correct?

ACC is the strongest ocean current in the world connecting the Atlantic, Pacific, Indian Oceans.
The weakening of ACC could lead to a decrease in ocean capacity to act as a carbon sink.
ACC plays a critical role in preventing the spread of non native species to Antarctica.

Select the correct answer using the codes below:

A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2, and 3

Correct Answer: D)

Explanation:

Statement 1 is correct. ACC is strongest ocean current in the world & it plays a key role in connecting the Atlantic, Pacific, Indian Oceans.

Statement 2 is correct. The weakening of ACC could reduce the ocean ability to absorb carbon making it less efficient as a carbon sink. This is significant for global warming as the ocean plays a vital role in sequestering atmospheric CO2.

Statement 3 is correct. ACC acts as natural barrier to prevent non-native marine species from reaching Antarctica. If it weakens species like mollusks, shrimp, bull kelp could invade disrupting the Antarctic food web.