Giant Iceberg Breaks Off from Antarctic Glacier

(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)

News from the Reuters

Going green with nuclear power

The Nuclear Safety Commission and the Atomic Energy Commission have issued their annual reports for 2009, in which they call for the promotion of nuclear energy as an important means of fighting global warming. Nuclear power plants do not emit carbon dioxide while operating.

The reports came as the Hatoyama administration is pushing a policy of reducing greenhouse gas emissions 25 percent from 1990 levels by 2020. Under the Kyoto Protocol, Japan agreed to slash emissions by 6 percent from 1990 levels during the 2008-2012 period, but present levels still exceed those of 1990.

To both reduce CO2 emissions and increase the supply of electricity, the NSC and the AEC call for improving the operation rate of Japan's 54 nuclear power plants, which produce about 30 percent of the nation's electricity.

In the 1990s, the plants' average operation rate was around 80 percent. But from 2007 it dropped to around 60 percent. In contrast, nuclear power plants in Europe, North America and South Korea have enjoyed an operation rate of 80 percent to 90 percent throughout the past decade. The safety commission says that a 1 percent improvement in the operation rate would be equivalent to a reduction of some 3 million tons of CO2 annually. It is estimated that if the operation rate returns to 80 percent, Japan will be able to reduce its CO2 emissions by about 5 percent.

But improving the operation rate will not be an easy job. Eighteen — or one third — of Japan's 54 reactors are more than 30 years old, and one is 40 years old. Another will turn 40 this year. Pipes and reactor components are deteriorating rapidly in nuclear power plants built in the 1960s and '70s.

The safety commission calls for lengthening the interval between regular checks of nuclear power plants, prolonging the operational life of such plants to more than 40 years and increasing their output by about 5 percent — all steps that increase safety risks. A series of mishaps at nuclear power plants has lowered people's trust. In its pursuit of an improved operation rate, the nuclear power industry must take every possible step to ensure that safety is not compromised.

Editorial from Japan Times