Vast iceberg may alter ocean currents

An iceberg the size of Luxembourg has broken off from a glacier in Antarctica after being rammed by another giant iceberg, scientists said Friday, in an event that could affect ocean circulation patterns.

The 965 sq mile iceberg broke off earlier this month from the Mertz Glacier’s 100-mile floating tongue of ice that sticks out into the Southern Ocean.

The collision has since halved the size of the tongue that drains ice from the vast East Antarctic ice sheet.

“The calving itself hasn’t been directly linked to climate change, but it is related to the natural processes occurring on the ice sheet,” said Rob Massom, a senior scientist at the Australian Antarctic Division and the Antarctic Climate and Ecosystems Cooperative Research Center in Hobart, Tasmania.

Both organizations, along with French scientists, have been studying existing giant cracks in the ice tongue and monitored the bumper-car-like collision by the second iceberg, B-9B. This 60-mile long slab of ice is a remnant of an iceberg of more than 1,900 sq miles that broke off, or calved, in 1987, making it one of the largest icebergs ever recorded in Antarctica.

The Mertz glacier iceberg is among the largest recorded for several years, at about two-thirds the size of Rhode Island.

In 2002, a 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.

‘Pretty big nudge’
The two icebergs are now drifting together about 60 to 90 miles off Antarctica following the collision on Feb. 12 or 13, said Australian Antarctic Division glaciologist Neal Young.

“It gave it a pretty big nudge,” Young said of the icebergs’ collision. “They are now floating right next to each other.”

Oceans act like a giant flywheel for the planet’s climate by shifting heat around the globe via myriad currents above and below the surface.

Massom said the shearing off of the ice tongue and the presence of the Mertz and B-9B icebergs could affect global ocean circulation.

The area is an important zone for the creation of dense, salty water that is a key driver of major worldwide currents.

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