Scientists see glacier collision as chance to learn secrets

Posted Jan 5, 2011 by Lynn Curwin
Scientists believe that a collision between an iceberg and a glacier in the Antarctic will allow them to gather new information, as it provides them with access to an area of seabed previously unseen.
Neal Young/Australian Government press release
When a 97-kilometre long iceberg hit the Mertz Glacier in early 2010 a 78-kilometre long and 39-kilometre wide piece of the glacier broke away, in what is known as calving.
The tongue of the glacier had fractures on both sides for many years. It had protruded more than 100 kilometres before being struck but has now been reduced to 20-25 kilometres.
A team of about 40 international scientists left Hobart, Australia on the Aurora Australis on Tuesday to study the area. It will take them approximately a month to reach the area.
"The calving of the iceberg has exposed parts of the seabed which haven't been available for study in our lifetimes," the Daily Mercury quoted the Australian Antarctic Division’s Acting Chief Scientist, Dr Martin Riddle, as saying.
"It's a biological hotspot supporting everything from microscopic photoplankton, right up to seals and whales.”
He said whales, penguins and seals feed on plankton in the area, as it is one of the few locations not ice-covered during the Antarctic winter.
“On the voyage, underwater cameras will be deployed to explore the ocean floor in the area previously covered by the glacier tongue,” he stated in an Australian Government press release.
“I expect to see new and unusual animals on the sea-floor as the area has been covered by ice hundreds of metres thick for about 80 years – this is a once in a life-time opportunity to discover what lives in these inaccessible places under the ice.”
The region is also one of the few where dense, salty water forms at the surface and sinks four or five kilometres to the sea floor.
“This sinking of dense water near Antarctica is a key link in a network of ocean currents that influences global climate patterns,” Dr Steve Rintoul, voyage leader and oceanographer with the Antarctic Climate and Ecosystems Cooperative Research Centre, said in the press release.
“One goal of the expedition is to see how the calving of the large ice tongue has affected the formation of dense bottom water in the region.”
Scientists will measure the impact of ocean acidification on phytoplankton, which is the base of the food chain in the ocean.
They will take measurements of carbon dioxide stored in the ocean.
Rintoul explained that the ocean slows the rate of climate change by soaking up carbon dioxide but this is causing the ocean more acidic, which affects the ability of some organisms to form shells and for structures like reefs to develop.
“By comparing our new measurements to earlier observations, we will determine how the temperature, salinity and circulation of the Southern Ocean is changing,” he added.
“This information will help us track how rapidly climate is changing and help us improve projections of future change.”
The Aurora Australis is expected to return to Hobart in February.
The expedition is part of a series begun in 1991 to assess changes in the Southern Ocean.
The calving was detected a a French-Australian team working on a project called “CRACICE” (Cooperative Research into Antarctic Calving and Iceberg Evolution). Images of the event can be seen in a press release from Antarctic Climate & Ecosystems.