Page 2/2 - Posted September 3, 2010
Ross Ice Shelf collapsed previously
In fact, the Ross Ice Shelf has disappeared in the past based on previous research, most recently by the ANDRILL program , which drilled sediment cores in the Ross Sea Embayment during the 2006-07 and 2007-08 field seasons. The data from one core suggested that during the mid-Pliocene, about 3.5 million years ago, the WAIS periodically collapsed.
Global temperatures were higher during that time, and atmospheric carbon dioxide levels were about 400 parts per million (ppm). CO2 levels are about 393 ppm today.
“There are no annually resolved climate records from the Pliocene period,” Bertler noted. “To provide constraints on the rate of change, the RICE project attempts the next best thing — it seeks to reconstruct the behavior of the Ross Ice Shelf retreat during a time of rapid change.”
That would be the past 30,000 years, when global temperatures increased by 6 degrees centigrade and global sea level rose by about 120 meters. However, the Ross Ice Shelf retreat occurred predominantly during the past 8,000 years, when global temperatures stabilized.
“We will correlate reconstructed local climate conditions with the precisely dated retreat history,” Bertler said. “The RICE record will provide important knowledge to improve predictions on the future behavior of the Ross Ice Shelf and will help to advance models to improve estimates of future change.”
Conway said scientists believe that melting under the ice shelf helps drive the changes in the ice sheet. In addition, rising sea level caused by deglaciation in the Northern Hemisphere also causes the grounding line to retreat.
“However, it takes some time for the ice sheet to respond to these changes. We are trying to improve our understanding of the response time to different changes,” he said.
New Zealand designed and built a new drill for the project based on a Danish design, called the Hans Tausen Drill . Alex Pyne , projects manager at the Antarctic Research Centre’s science drilling office, was behind the effort. Pyne also served as the drilling science coordinator and drill site manager for ANDRILL.
The drill has a reach of 1,000 meters, which makes it an intermediate drill in the world of ice-core drilling. In comparison, the Deep Ice Sheet Core (DISC) drill being used for a project at WAIS Divide by the USAP is drilling an ice core almost 3.5 kilometers deep.
However, the Kiwi drill doesn’t have the luxury of being transported in large cargo aircraft. All the equipment for the camp must fit into small ski-equipped Twin Otter or Basler aircraft.
“The technological challenge was to keep the system lightweight and individual pieces small enough [so] that this was possible,” Bertler said.
Noted Conway, “It is a lighter camp than an American camp.”
Conway’s team will spend about a month on the island, named after President Franklin D. Roosevelt by the famous polar explorer Rear Adm. Richard E. Byrd in 1934 after its discovery. He hopes for better weather than what they had in 1997-98.
“We’re hoping it won’t be too stormy. It’s not as stormy as WAIS Divide,” he said. “It’s very exciting. I’m thrilled and feel very privileged to be going back there and collaborating with [New Zealand].”