Antartica ice melts and Southern Ocean is becoming fresher

Mystery of why southernmost water is
becoming less salty is solved.

For decades, scientists have puzzled over why the southernmost waters in the world were becoming less salty, and now it looks like we might have an answer.

Scientists have found that the Southern Ocean – which surrounds Antarctica – has been experiencing an increase in sea ice, which is slowly drifting northwards. When this saltless sea ice melts back into the ocean and into warmer northern seas, it freshens the saltwater around it, reducing its salinity.

According to a new study led by researchers at ETH Zurich in Switzerland, this cold fresh meltwater enters the ocean at the sea ice periphery. It then sinks below the warmer surface waters, forming what's called the Antarctic Intermediate Water.

At depths of around 600 to 1,500 metres (1,969 to 4,921 feet), this low-salinity water then spreads, extending as far northwards as the Equator, and reaching as far as the Iberian peninsula in the eastern Atlantic.

Scientists previously thought the phenomenon might be due to increased rainfall over the Southern Ocean, but the new study's authors disagree.

Read the ScienceAlert story - “As sea ice around Antarctica melts, the Southern Ocean is becoming fresher.”