The iceberg, which measures 50 miles by 25 miles, snapped off the Mertz Glacier, a 100-mile long tongue of ice earlier this month.
It was dislodged by an older, 60-mile-long iceberg called B9B, which broke off the glacier in 1987.
The two icebergs, which have a combined weight of 1,000billion tons, are now floating 90 miles off Antarctica's northern coast.
Experts are now concerned that the iceberg - which contains enough fresh water to supply a fifth of the world's population for a year - could block the formation of cold, salty water, known as 'bottom water', which drives the ocean's circulation system.
Any changes to currents would affect weather patterns around the world. Britain would become far colder without the mild sea water brought from the south west by the North Atlantic drift.