another huge iceberg breaks off in antarctica

this is so exciting.  terraforming, going on right before our eyes.

Giant iceberg breaks off from Antarctic glacier

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

The 2,500 sq km (965 sq mile) iceberg broke off earlier this month from the Mertz Glacier’s 160 km (100 miles) 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 97 km long slab of ice is a remnant of an iceberg of more than 5,000 sq km 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. In 2002, a iceberg about 200 km 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.

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 global ocean circulation. This is produced in part through the rapid production of sea ice that is continually blown to the west.

“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,” he said.

He said there was a risk both icebergs would become grounded on banks or shoals in the area, disrupting the creation of the dense, salty water and the amount that sinks to the bottom of the ocean, he said.

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.

(Reporting by David Fogarty; Editing by Alex Richardson)

and here’s more from science daily

Two large rifts cutting through the southern part of the glacier tongue have been developing over many years. Rifting progressed from the eastern margin of the Mertz Glacier in the 1990s until 2002 when another rift started to develop from the western side. Recently the two rifts had almost joined and the western rift subsequently became very active, leaving the northern part of the glacier tongue attached like a “loose tooth.” The final break when B-9B collided with the eastern flank of the glacier tongue. But it did not simply separate along the line of these pre-existing rifts. The break followed most of the western rift and the ice sheared across the section with the eastern rift to produce a clean line which is allowing the southern end of the iceberg to move freely past the remainder of the tongue.

B-9B, itself about 97 km by 20-35 km, is a large part of the B9 iceberg that calved from the Ross Ice Shelf in 1987 and drifted westwards until it ran aground in 1992 on the Ninnis Bank, less than 100 km to the east of the Mertz Glacier Tongue. After remaining in roughly the same location for about 18 years, B-9B recently ungrounded and rotated to collide with the Mertz Glacier Tongue. The Mertz Glacier Tongue originates in a 60km long fjord and had extended a further 100km into the Southern Ocean. It advanced into the ocean at slightly more than 1 km per year. The new iceberg thus represents about 70 years of glacier advance.


About jeanne

artist, grandma, alien

Posted on February 27, 2010, in antarctica, research and tagged , , . Bookmark the permalink. Leave a comment.

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