An iceberg the size of Luxembourg that contains enough fresh water to
supply a third of the world's population for a year has broken off in
the Antarctic continent, with possible implications for global ocean
circulation, scientists said today.

The iceberg, measuring about
50 miles by 25, broke away from the Mertz glacier around 2,000 miles south of Australia after being rammed
by another giant iceberg known as B-9B three weeks ago, satellite
images reveal. The two icebergs, which both weigh more than 700m
tons, are now drifting close together about 100 miles north of Antarctica.

Rob Massom, a senior
scientist at the Australian Antarctic Division and the Antarctic
Climate and Ecosystems Cooperative Research Centre in Hobart, Tasmania,
said the location of the icebergs could affect global ocean circulation
and had important implications for marine biology in the region.

The
concern is that the massive displacement of ice would transform the
composition of sea water in the area and impair the normal circulation
of cold, dense water that normally supplies deep ocean currents with
oxygen.

"Removal of this tongue of floating ice would reduce the
size of that area of open water, which would slow down the rate of
salinity input into the ocean and it could slow down this rate of
Antarctic bottom water formation," Massom told Reuters.

Mario
Hoppema, chemical oceanographer at the Alfred Wegener Institute for
Polar and Marine Research in Germany, said that as a result "there may
be regions of the world's oceans that lose oxygen, and then of
course most of the life there will die".

B-9B is a remnant of a
2,000-square-mile iceberg that calved in 1987, making it one of the
largest icebergs recorded in Antarctica. It drifted westwards for 60
miles before becoming grounded in 1992. It has recently re-floated
itself and rotated into the Mertz tongue.

The Mertz glacier
iceberg is among the largest recorded for several years. In 2002, an
iceberg about 120 miles long broke off from Antarctica's Ross ice shelf.
In 2007, a iceberg roughly the size of Singapore broke off from the
Pine Island glacier in west Antarctica.