Context

Scientists reconstructed the history of the world’s most potent ocean circulation over the previous 5.3 million years, including how it is linked to global climate.

Key Findings of the Research

• Sea Level Rise: The current speeding of the Antarctic circumpolar current does not bode well for the stability of Antarctica’s ice sheets, which are already losing mass at an average rate of about 150 billion tonnes per year, contributing to sea-level rise.
• Role of Antarctic Circumpolar Current: Antarctic circumpolar current plays a key role in regulating global climate and is also the world’s most powerful and primary means of inter-basin exchange of heat, carbon dioxide, chemicals and biology.
• Encircling of Antarctica: Powered by continuous westerly winds, the ocean current circles Antarctica clockwise at about 4 kilometers per hour, carrying 165 million to 182 million cubic metres of water each second.
• Gaining of Wind Strength: Winds over the Southern Ocean, which encircles Antarctica, has gained strength by about 40 per cent in the last four decades.
• Speeding of Antarctic Circumpolar Current: This, in turn, has sped up the Antarctic Circumpolar Current, causing relatively warm water from higher latitudes reaching the South Pole. 
• Melting of ice shelves: In some parts, especially western Antarctica, these warm waters are melting the undersides of the ice shelves.
• Cause of loss of Ice: This loss of ice can be attributed to increased heat transport to the south
• Effect of Stronger Antarctic Circumpolar Current: A stronger Antarctic circumpolar current means more warm, deep water reaches the ice-shelf edge of Antarctica.

About Antarctic Circumpolar Current

• Direction: Antarctic Circumpolar Current is an ocean current that runs from west to east around Antarctica.

• Role of Southern ocean: The Southern Ocean is a continuous body of water with a rushing current that simultaneously isolates Antarctica’s coastal ocean and offers critical chemical fertilizers to the Antarctic ecology.
• Type of Current: The largest wind-driven current on Earth is called the Antarctic Circumpolar Current (ACC). 
  • The only current that links the Atlantic, Pacific, and Indian oceans and circumnavigates the entire earth.
• Driving Force: It is propelled by strong westerly winds and was discovered by Edmund Halley.
• Acts as a Barrier: The Antarctic Current is a vast flow of water that serves as a barrier between the Southern and Northern Oceans.
• World Circulation: Antarctica is also the source of water that moves across the deep ocean as part of the Global Ocean Conveyor (world circulation).
  • The global ocean conveyor belt is a dynamic system of deep-ocean circulation driven by temperature and salinity.
• Antarctic continental shelf: Water that flows at the ocean’s bottom is formed on the Antarctic continental shelf, particularly in the Weddell and Ross Seas. 
• High Marine production: It is the location where cold Antarctic seas meet Sub-Antarctic water, resulting in an upwelling zone (a zone of high marine production).
• Formation of  Antarctic Intermediate Water: Different weather conditions further north, at 45-55 degrees south, result in the formation of another water body known as Antarctic Intermediate Water.
  • In this area, precipitation is greater than evaporation, hence the salinity of the water is low.

DOWNLOAD PDF