"We now have a more complete core record from the middle Miocene and a step into a colder period of time, and that was one of our key targets," Florindo said. "It will tell an important story when we put together our recovery with the record of last season. This is exciting science and it will echo loudly in the scientific community."
The middle Miocene has long been held as one of the fundamental time intervals in development of the modern Antarctic ice sheets. It encompassed a change from a warm climate optimum approximately 17 million years ago to the onset of major cooling approximately 14 million years ago, and the formation of a quasi-permanent ice sheet on East Antarctica. Florindo and Harwood said fossils and sediments deposited during this year's ANDRILL target interval suggest the persistence of warmer-than-present conditions over an extended period of the middle and late Miocene when the western Ross Sea and McMurdo Sound resembled the modern climate conditions of southernmost South America, southwestern New Zealand, and southern Alaska, rather than the cold polar climate of today.
"Until now, most climatic interpretations for this time period has been based on measurement of oxygen isotopes in the deep sea, far from Antarctica," Harwood said. "The cores we've recovered will give us a high resolution history of paleoclimate change directly from the Antarctic continent."
The sediment cores reflect deposition close to or beneath grounded glaciers, alternating with fine-grained sediments, which provide clear evidence for ice advance and substantial retreat during main climate transitions, Florindo and Harwood said. They said programs like ANDRILL are extremely important because of the uncertainties about t
|Contact: Tom Simons|
University of Nebraska-Lincoln